Chapter 2 - Prenatal Development, Pregnancy, and Birth Part 1 – The Foundation I. Setting the Context Throughout history, societies have seen pregnancy as an exciting and frightening time of life. Cultures used to make heroic efforts to keep pregnant women calm and happy. Societies celebrated pregnancy milestones This chapter draws on the miracle of twenty-first century science to explore each pregnancy concern. Charting marvelous milestones of prenatal development, pregnancy, and birth. II. The First Step: Fertilization A. What structures are involved in reproduction? What physiological process is involved in conceiving a child? What happens at the genetic level when a sperm and an egg unite to form a human being? The Reproductive Systems 1. Uterus - The pear-shaped muscular organ in a woman’s abdomen that houses the developing baby. a. The uterus is lined with a velvety tissue, the endometrium, which thickens in preparation for pregnancy and, if that event does not occur, sheds during menstruation. 2. Cervix - The neck, or narrow lower portion, of the uterus. a. During pregnancy, this thick uterine neck must perform an amazing feat: 1. Be strong enough to resist the pressure of the expanding uterus 2. Be flexible enough to open fully at birth. 3. Fallopian Tube - One of a pair of slim, pipe like structures that connect the ovaries with the uterus. a. Serve as conduits to the uterus. 4. Ovary - One of a pair of almond shaped organs that contain a woman’s ova, or eggs. 5. Ovum (ova) - An egg cell containing the genetic material contributed by the mother to the baby. B. Ova are all mainly formed at birth receptive for about 24 hours while in the tube’s outer part. emits chemical signals as to its location The Process of Fertilization 1. Fertilization - The union of sperm and egg. The pathway to fertilization, begins at ovulation Sperm take a few hours to journey from the cervix to the tube. However, sperm can live almost a week in the uterus, which means that intercourse several days prior to ovulation may also result in fertilization Once sperm reaches the center of the ovum, the nuclei of the male and female cells move slowly together. When they meld into one cell, fertilization has occurred. 2. Ovulation - The moment during a woman’s monthly cycle when an ovum is expelled from the ovary. Typically occurs around day 14 of a woman’s cycle a fallopian tube suctions the ovum in the tube begins vigorous contractions, propelling the ovum it takes three-days to reach the uterus. 3. Hormones - Chemical substances released in the bloodstream that target and change organs and tissues. orchestrate ovulation as well as the other events that program pregnancy. 4. Testes - Male organs that manufacture sperm. continually manufacturing sperm. An adult male typically produces several hundred million sperm a day. During intercourse, sperm is expelled into the vagina a small proportion enter the uterus and make their way up the fallopian tubes of the several hundred million sperm expelled, only 200-300 reach the egg sperm find the ovum and begin to burrow in once they penetrate the center - innermost part – the chemical composition of the ovum wall changes, shutting out the other sperm. C. The Genetics of Fertilization 1. chromosome - A threadlike strand of DNA located in the nucleus of every cell that carries the genes, which transmit hereditary information. Once fertilized, each chromosome pair (one from mother and one from father) is a match, except for the sex chromosomes. Each ovum carries an X chromosome Only males carry the Y – determining sex a. X vs Y The X is longer and heavier than the Y. Y - lighter, faster - we get a boy (XY). X - more resilient, slower - we get a girl (XX). b. Y’s are statistically more successful scientists estimate that 20 % more male than female babies are conceived However, prenatal period is particularly hard on males. While the odds still favor of having a boy, more males die in the uterus Decreasing odds to only 5 % more boys than girls make it to birth c. throughout life, males continue to be the less hardy sex, dying off at higher rates at every age. 2. DNA (deoxyribonucleic acid) - The material that makes up genes, which bear our hereditary characteristics. 3. gene - A segment of DNA that contains a chemical blueprint for manufacturing a particular protein, responsible for carrying out the physical processes of life. 4. Cells – Each cell in our body has 46 chromosomes—except the sperm and ova, which have 23 When the nuclei of these two cells, called gametes, combine at fertilization, their chromosomes align in pairs to again comprise 46. Ensuring that each human life has an identical number of chromosomes and every human being gets half of its genetic heritage from the parent of each sex. III. A. Prenatal Development microscopic, fertilized ovum divides millions of times differentiates into a living child miraculous transformation takes place in three stages. First Two Weeks: The Germinal Stage 1. Germinal Stage - The first 14 days of prenatal development, from fertilization to full implantation. cell mass has not fully attached to the uterine wall 2. Zygote - A fertilized ovum. Within 36 hours, makes its first cell division the tiny cluster of cells divides every 12 to 15 hours as it wends its way down the fallopian tube. When they enter the uterine cavity, they differentiate into layers some form pregnancy support structures, others the child-to-be. 3. Blastocyst - The hollow sphere of cells formed during the germinal stage in preparation for implantation. ball of roughly 100 cells, responsible for implantation on uterine wall 4. Implantation - The process in which a blastocyst becomes embedded in the uterine wall. Blastocyst seeks a landing site on the upper uterus. Its outer layer develops projections and burrows in blood vessels proliferate to form the placenta 5. placenta - The structure projecting from the wall of the uterus during pregnancy through which the developing baby absorbs nutrients. B. Week 3 to Week 8: The Embryonic Stage 1. embryonic stage - The second stage of prenatal development, lasting from week 3 - week 8. Most fast-paced period of development. All the major organs are constructed. By the end of this stage, the clump of cells looks like a recognizable human being a. One early task is to construct the conduit responsible for all development. After the baby hooks up to the maternal bloodstream—which will nourish its growth— nutrients must reach each rapidly differentiating cell. By the third week after fertilization, the circulatory forms Its pump, the heart, starts to beat. b. At the same time, the rudiments of the nervous system appear. Between 20 and 24 days after fertilization, an indentation forms along the back of the embryo, closing to form the neural tube 2. neural tube - A cylindrical structure that forms along the back of the embryo and develops into the brain and spinal cord. The upper part becomes the brain. Its lower part forms the spinal cord. Although it is possible to “grow” new brain cells throughout life, almost all of those remarkable branching structures, called neurons, originated in neural tube cells formed during our first months in the womb. 3. neuron - A nerve cell. Cause us to think, respond, and process information 4. Further formation C. At day 26, arm buds form by day 28, leg swellings erupt. At day 37, rudimentary feet start to develop. By day 41, elbows, wrist curves, and the precursors of fingers can be seen. Several days later, raylike structures that will become toes emerge. By about week 8, the internal organs are in place. What started out looking like a curved stalk, then an alien, now appears like a human being. Principles of Prenatal Development 1. proximodistal sequence - The developmental principle that growth occurs from the most interior parts of the body outward. from a cylindrical shape, the arms and legs grow outward and then (not unexpectedly) the fingers and toes protrude. Growth follows the proximodistal sequence, from the most interior (proximal) part of the body to the outer (distal) sides. From a huge swelling that makes the embryo look like a mammoth head, the arms emerge and the legs sprout. 2. cephalocaudal sequence - The developmental principle that growth occurs in a sequence from head to toe. Development takes place according to the cephalocaudal sequence, meaning from top (cephalo = head) to bottom (caudal = tail). 3. mass-to-specific sequence - The developmental principle that large structures (and movements) precede increasingly detailed refinements. Finally, nature starts with the basic building blocks and then fills in details. a. A head forms before eyes and ears; b. legs are constructed before feet and toes. c. Mass-to-specific sequence, or gross (large, simple) structures before smaller (complex) refinements. The third principle of body growth. You will see in the next chapters; the same patterns apply to growth and motor skills after the baby leaves the womb. D. Week 9 to Birth: The Fetal Stage 1. fetal stage - The final period of prenatal development, lasting seven months, characterized by physical refinements, massive growth, and the development of the brain. development occurs at a more leisurely pace. The eyebrows, fingernails, and hair follicles that develop from weeks 9 to 12, The cushion of fat that accumulates during the final weeks It takes seven months to transform the embryo into a resilient baby ready to embrace life 2. The Brain During the late embryonic stage, a mass of cells accumulates within the neural tube that will eventually produce the more than 100 billion neurons composing our brain. From this zone, the neurons migrate to a region just under the top of the differentiating tube When the cells assemble in their “staging area,” by the middle of the fetal period, they lengthen, develop branches, and interlink. This interconnecting process—responsible for every human thought and action—continues until almost our final day of life. The brain almost doubles in size from month 4 to month 7 & has the wrinkled structure of an adult. At around month 6, the fetus can hear By month 7, the fetus is probably able to see & by this time, with high-quality medical care, a few babies can survive. 3. age of viability - The earliest point at which a baby can survive outside the womb. has dropped to 22 to 23 weeks—almost halving the 38 weeks the fetus normally spends in the womb. By week 25, in affluent nations, the odds of survival are more than fifty-fifty it is vitally important that the fetus stay in the uterus as long as possible. being born too early (and too small) can make a lifelong impact in health. 4. umbilical cord The structure that attaches the placenta to the fetus, through which nutrients are passed and fetal wastes are removed. 5. amniotic sac - A bag-shaped, fluid-filled membrane that contains and insulates the fetus. provides insulation from infection and harm IV. Pregnancy 1. gestation The period of pregnancy The 266- to 277-day gestation period (or pregnancy) is divided into three segments called trimesters 2. trimester - One of the 3-monthlong segments into which pregnancy is divided. each comprising roughly three months. health-care professionals date the pregnancy from the woman’s last menstrual period. Pregnancy differs, however, from the universally patterned process of prenatal development. A. Despite having classic symptoms, here individual differences are the norm Scanning the Trimesters 1. First Trimester: Often Feeling Tired and Ill After the blastocyst implants in the uterus, pregnancy often signals its presence through unpleasant symptoms. Many women feel faint. They may get headaches or must urinate frequently. They may feel incredibly tired. Their breasts become tender, painful to the touch. Many women do not need that tip-off—a missed menstrual period—to realize they are carrying a child. a. Hormones Hormones trigger these symptoms. After implantation, the production of progesterone, the hormone responsible for maintaining the pregnancy—surges. The placenta produces its own unique hormone, human chorionic gonadotropin (HCG), thought to prevent the woman’s body from rejecting the “foreign” embryo. Given this hormonal onslaught, the body changes, and the fact that the blood supply is being diverted to the uterus, the tiredness, dizziness, and headaches make sense. b. Morning Sickness Morning sickness—nausea and sometimes vomiting—affects at least two out of every three women during the first trimester This well-known symptom is not confined to the morning. Many women feel queasy all day. A few cannot keep any food down. Men sometimes develop morning sickness along with their wives! This phenomenon has its own special name: couvade The queasiness is at its height when the organs are forming, toward the end of the first trimester, it usually disappears. Munching on bread products helps. Strong odors make many women gag. Evolutionary psychologists theorize that, before refrigeration, morning sickness prevented the mother from eating spoiled meat or toxic plants, which could be especially dangerous during the embryo phase Some research suggests that women with morning sickness are more likely to carry their babies to term. c. miscarriage - The naturally occurring loss of a pregnancy and death of the fetus. Roughly 1 in 10 pregnancies end in a first trimester fetal loss. For women in their late thirties, the chance of miscarrying during these weeks escalates to 1 in 5. Many miscarriages are inevitable— caused by genetic problems in the embryo that are incompatible with life. 2. Second Trimester: Feeling Much Better and Connecting Emotionally By week 14, the uterus dramatically grows a. quickening A pregnant woman’s first feeling of the fetus moving inside her body. Occurs around week 18 a sensation like bubbles that signals the baby kicking in the womb The woman feels viscerally connected to a growing human being. 3. Third Trimester: Getting Very Large and Waiting for Birth Backaches, leg cramps; numbness and tingling as the uterus presses against the nerves of the lower limbs; heartburn, insomnia, and anxious anticipation uterine contractions occurring irregularly as the baby sinks into the birth canal and delivery draws very near. Although women often do work up to the day of delivery, health-care workers advise taking time off to rest and relying on caring loved ones to help cook and clean during the final months. B. Actually, having caring loved ones is vital during all nine months! Pregnancy Is Not a Solo Act 1. Pregnancy has a different emotional flavor depending on the wider world. What forces turn this joyous time of life into nine months of distress? a. One influence lies in economic concerns. 1) Studies routinely show that low socioeconomic status puts pregnant women at risk of feeling demoralized and depressed 2) Imagine coping with the stresses associated with being poor, worrying about making ends meet, perhaps not getting adequate prenatal care, and you will understand why pregnancy is more likely to be one of life’s great joys when an expectant mother is comfortably middle class. 3) The main force, however, applies to both affluent and poor women alike—feeling loved by one’s mate 4) From dealing with problems on the pregnancy pathway, to handling birth and the new baby, having a caring partner is critically important in how women cope What matters is whether a woman feels generally cared about and loved Suppose you were married, but your spouse was hostile to your pregnancy. Wouldn’t you rather be going through this journey with a loving family or good friends? C. What About Dads? fathers are also bonded to their babies-to-be They can feel just as devastated when a pregnancy doesn’t work out. in coping with this trauma, men have a double burden. 1) They may feel compelled to put aside their feelings to focus on their wives 2) Plus, because the loss of a baby is typically seen as a “woman’s issue,” the wider world tends to marginalize their pain. 3) husbands are “pregnant” in spirit along with their wives. V. We should never thrust their feelings aside. we need to realize that expectant fathers need cherishing, too Threats to the Developing Baby A. birth defect A physical or neurological problem that occurs prenatally or at birth. Many birth defects don’t seriously impair a baby’s ability to have a fulfilling life. Often birth defects result from a complex nature-plus-nurture interaction. Fetal genetic vulnerabilities combine with environmental hazards in the womb. Threats from Outside: Teratogens teratogen - A substance that crosses the placenta and harms the fetus. may be an infectious disease; a medication; a recreational drug; environmental hazards, such as radiation or pollution; or the hormones produced by a pregnant woman under extreme stress. the infectious disease called rubella (German measles) often damaged a baby’s heart or ears, depending on the week during the first trimester when a mother contracted the disease. The sedative Thalidomide, prescribed in Europe during the late 1950s to prevent morning sickness, impaired limb formation, depending on which day after fertilization the drug was imbibed. 1. Basic Teratogenic Principles sensitive period - The time when a body structure is most vulnerable to damage by a teratogen, typically when that organ or process is rapidly developing or coming “online.” a. Teratogens are most likely to cause major structural damage during embryonic stage. Before implantation, teratogens have an all-or-nothing impact. either inhibit implantation & cause death or leave the not yet-attached blastocyst unscathed. during organ formation; major body structures are most likely to be affected. Therefore, unless expectant mothers have a chronic disease that demands continuing, physicians advise forgoing any medications during the first trimester with medications & pregnancy, it can be a balancing act. At times, there are no perfect choices. b. Teratogens can affect the developing brain throughout pregnancy. during the 2nd & 3rd trimesters, potential for neurological damage extends for all nine months. typically increasing the risk of developmental disorders. any condition that compromises normal development—from delays in reaching basic milestones, such as walking or talking, to learning problems and hyperactivity. c. Teratogens have a threshold level above which damage occurs. For instance, women who drink more than four cups of coffee a day throughout pregnancy have a slightly higher risk of miscarriage; but having an occasional Diet Coke is fine d. Teratogens exert their damage unpredictably, depending on fetal & maternal vulnerabilities. mothers-to-be metabolize toxins differently, and babies differ genetically in susceptibility. Therefore, the damaging effects of a teratogen can vary. You may know a child whose mother drank heavily during pregnancy, but we do not know where the teratogenic threshold lies in any one case. The damaging impact of a teratogen may show up during infancy or manifest itself years later. An example of this - a mother was given a drug called diethylstilbestrol (DES) while she was pregnant to prevent miscarriage. After the baby grew and became pregnant in her the early twenties, she developed cancerous cells on the cervix, requiring surgery. She had three miscarriages before deciding to adopt 2. The Teratogenic Impact of Medicines and Recreational Drugs With recreational drugs, the choice is clear. Each substance is potentially teratogenic. a. Tobacco & alcohol are woven into the fabric of daily 1) SMOKING Every time she reads the information on a cigarette pack, a pregnant woman gets a reminder that she may be doing her baby harm. Still, pregnant women smoke, tobacco use during this time this practice is such a “no, no,” so, many women lie about quitting. a national U.S. study measured blood levels for tobacco use, found roughly 1 in 4 pregnant smokers had falsely reported quitting. The main danger with smoking is giving birth to a smaller-than-normal baby Nicotine constricts the mother’s blood vessels, reducing blood flow to the fetus, preventing a full complement of nutrients to reach the child. Smoking—and giving birth to a small child—raises the risk of developmental problems like hyperactivity and makes newborns less able to regulate their sleep 2) ALCOHOL used to be encouraged to pregnant women to have a nightcap to relieve stress. In Italy, drinking red wine during pregnancy was said to produce a healthy, rosy-cheeked child! During the 1970s, evidence mounted for fetal alcohol syndrome (FAS), and these prescriptions were quickly revised. The defining qualities of fetal alcohol syndrome include a smaller-than-normal birth weight and brain; facial abnormalities (such as a flattened face); and developmental disorders ranging from serious intellectual disability to seizures and hyperactivity. Women who binge-drink, or pregnant women who regularly consume several drinks nightly, are at highest risk of giving birth to a baby with fetal alcohol syndrome. Their children, at a minimum, may be born with a less severe syndrome called fetal alcohol spectrum disorders, characterized by deficits in learning and impaired mental health. As alcohol crosses the placenta, it causes genetic changes that impair neural growth Ironically, trying to conceive has no influence on alcohol use Pregnant women who drink regularly tend to be anxious or depressed. Every U.S. public health organization recommends no alcohol during pregnancy. In Europe, having a cocktail or glass of wine is an expected practice during meals. This may explain why European physicians disagree with their U.S. counterparts: “One drink per day can’t possibly do the fetus harm” 3) Measurement Issues imagine the challenges researchers face exploring the impact of tobacco or alcohol on the developing child: The need to ask thousands of pregnant women to estimate how often they indulged in these “unacceptable” behaviors, then track the children for decades, looking for problems that might appear as late as adult life. Because the study is correlational, the difficulties might be due to; fetal alcohol syndrome (FAS) A cluster of birth defects due to mother’s alcohol consumption during pregnancy. other confounding causes. Pregnant women who drink are more likely to smoke And these women may be generally stressed out & feeling overly anxious may damage the developing child B. isolate the child’s symptoms to just tobacco or alcohol may not be possible HOT IN DEVELOPMENTAL SCIENCE: What Is the Impact of Prenatal Stress? 1. anxiety is normal during pregnancy, but excessive anxiety may cause premature labor, causing women to miscarry or have an unhealthy infant. a. High levels of the stress hormone cortisol, are transmitted to the fetus via the amniotic fluid, making babies irritable during the first months of life 2. with teratogens in general—let’s list two forces that increase these risks: a. The intensity, quality, and timing of the stress may matter. 1) Does the person have an overload of problems, few social supports, or is she experiencing a difficult or unwanted pregnancy? 2) Anxieties about fetal health, not unexpectedly, are more common in older moms 3) Excessive stress in the latter part of pregnancy increases the chance of premature labor 4) other researchers discovered traumatic events prior to getting pregnant compromised the baby’s health b. The person’s personality and coping style matters most. 1) developmentalists concluded that the critical variable relates to the way women handle stress a) Does the person behave proactively, taking constructive steps to confront problems, or bury her difficulties by using avoidant strategies? b) Denying distress, or passively breaking down, and, of course, resorting to binge drinking or smoking to cope, raises the risk of giving birth early and having a frail child. 2) Suppose the trauma is so overwhelming that it’s impossible to constructively cope. a) Imagine that while a woman is pregnant a disaster occurs—a war or an earthquake—or a person is so poor she doesn’t have enough to eat. b) Can these experiences have a lifelong impact on her child? 3. Is Pregnancy a Programmer of Old Age? The answer may be YES during World War II, the Germans cut off the food supply to Holland, putting that nation in a semi-starvation condition for a few months. miscarriages and stillbirths were far more frequent during this “Hunger Winter.” Even the surviving babies had enduring scars. Midlife heart disease rates were higher if a baby had been in the womb specifically during the Hunger Another study had a similar result: Babies born in the most impoverished sections of the UK were more susceptible to dying from cardiovascular disease at a young age deprivation in the womb linked to premature, age-related disease? may center on being born too small. Fetuses deprived of nutrients and/or exposed to intense maternal stress, may result in impaired growth and primes the baby to enter the world expecting “a state of deprivation” and to eat excessively or store fat. But while this strategy promotes survival when nutrition is scarce, it boomerangs—promoting obesity and a potentially shorter life, when a child arrives in the world overabundant in food. Is obesity (and adult chronic disease) caused just by personal lifestyle choices or partly promoted by a poor body-environment fit at birth? fetal programming research - New research discipline exploring the impact of traumatic pregnancy events and intense stress on producing low birth weight, obesity, and long-term physical problems. These questions are driving fetal programming research studies, exploring how intrauterine events may epigenetically change our genetic code. Will twenty-first-century scientists trace the roots of human development to experiences in the womb? Fetal programming research is action oriented. Ideally, we can take steps before birth to influence a child’s fate. C. Threats from Within: Chromosomal and Genetic Disorders When a birth defect is classified as “genetic,” there are two main causes. The child might have an unusual number of chromosomes, or a faulty gene (or set of genes) 1. Chromosomal Problems a. normal human chromosomal complement is 46. However, sometimes a baby with a missing or extra chromosome is conceived. Most of these fertilizations end in first-trimester miscarriages, as the cells cannot differentiate much past the blastocyst stage. Still, babies can be born with an abnormal number of sex chromosomes (such as an extra X or two, an extra Y, or a single X) and survive. In this case, although the symptoms vary, the result is often learning impairments and sometimes infertility. b. Survival is also possible when a child is born with an extra chromosome on a specific other pair. Down syndrome - The most common chromosomal abnormality, causing intellectual disability, susceptibility to heart disease, and other health problems; and distinctive physical characteristics, such as slanted eyes and stocky build. typically occurs because a cell-division error, (nondisjunction), in the egg or sperm causes an extra chromosome or piece of that copy to adhere to chromosome pair 21. Child is born with 47 chromosomes. During midlife, many adults with Down syndrome develop Alzheimer’s disease. A century ago, DS children rarely lived to adulthood. In the U.S. today, due to medical advances, average life expectancy of 60 years. This longevity gain can be a double-edged sword for caregivers concerned for their children when they can no longer care for them. Not every DS baby is dependent on a caregiver’s help. Sometimes learn to read and write, can live independently, hold down jobs, marry and have children, construct fulfilling lives. Although women of any age can give birth to DS babies, the risk rises exponentially among older mothers, as older ova being more apt to develop chromosomal faults. Over age 40, the chance of having a Down syndrome birth is 1 in 100; over age 45, it is 1 in 30. 2. Genetic Disorders a. single-gene disorder - An illness caused by a single gene. passed down according to three modes of inheritance: 1) They may be dominant, recessive, or sex-linked. 2) we get one copy of each gene from our mother and one from our father. 3) one member of each gene pair can be dominant. 4) If both members of the gene pair are not dominant (that is, if they are recessive), the illness will manifest itself only if the child inherits two of the faulty genes. b. dominant disorder - illness from inheriting 1 copy of the abnormal gene that causes the disorder. in the first category. If one parent harbors the problem gene (and so has the illness), each child the couple gives birth to has a fifty-fifty chance of also getting ill. Huntington’s Disease People with Huntington’s develop an incurable dementia in the prime of life. As a child you would probably have watched a beloved parent lose his memory and bodily functions, and then die. You would know that your odds of suffering the same fate are 1 in 2 You won’t know if you have it, as it shows up during the prime reproductive years. c. recessive disorder - illness from inheriting 2 copies of the abnormal gene that causes the disorder. in the second category. Unless a person gets two copies of the gene, one from each parent, that child is disease free. The odds of a baby born to two carriers (parents who each have one copy of that gene) having the illness are 1 in 4. Tay-Sachs carrier gene, you may have seen a beloved baby die in infancy. Nothing can be done. Infant nervous system disorder. With cystic fibrosis, your affected child would be subject to recurrent medical crises as his lungs filled up with fluid, and he would face a dramatically shortened life. While surviving to the teens with cystic fibrosis used to be rare, today these children can expect on average to live to their twenties and sometimes beyond d. sex-linked single-gene disorder - illness, carried on the mother’s X chromosome, typically leaves the female offspring unaffected but has a fifty-fifty chance of striking each male child. Most often, the woman is carrying a recessive (non-expressed in real life) gene for the illness on one of her two X chromosomes. Since her daughters have another X from their father (who doesn’t carry the illness), the female side of the family is typically disease free. Her sons, however—with just one X chromosome that might code for the disorder—have a fifty-fifty chance of getting ill, depending on whether they get the normal or abnormal version of their mother’s X. Because their single X leaves them vulnerable, sex-linked disorders typically affect males. Females can get the disorder if the mother is a carrier (having one faulty X) and the dad has the disorder (having the gene on his single X) With hemophilia, the life-threatening episodes of bleeding can be avoided by supplying the missing blood factor through transfusions. genetic testing - A blood test to determine whether a person carries the gene for a given genetic disorder. D. Interventions 1. Sorting Out the Options: Genetic Counseling genetic counselor - A professional who counsels parents-to-be about their own or their children’s risk of developing genetic disorders, as well as about available treatments. genetic counselors describe advances in treatment inform couples who are carriers for cystic fibrosis about biological strategies on the horizon, such as gene therapy. highlight the interpersonal and economic costs of having a child with this disease trained never to offer advice. Their goal is to permit couples to make a mutual decision 2. Tools of Discovery: Prenatal Tests ultrasound - In pregnancy, an image of the fetus in the womb that helps to date the pregnancy, assess the fetus’s growth, and identify abnormalities. Blood tests performed during the first trimester can detect (with reasonable accuracy) various chromosomal conditions, such as Down syndrome. Brain scans (MRIs) offer a vivid prenatal window on the developing brain The standard fetal diagnostic test has been a staple for over 40 years: the ultrasound. Ultrasounds, which now provide a clear image of fetus, are used to date the pregnancy and assess in utero growth, in addition to revealing physical abnormalities. chorionic villus sampling (CVS) - A relatively risky first trimester pregnancy test for fetal genetic disorders. During the first trimester, chorionic villus sampling (CVS) can diagnose a variety of chromosomal and genetic conditions. A physician inserts a catheter into the woman’s abdomen or vagina and withdraws a piece of the developing placenta for analysis. The advantage of CVS, is knowing early on about problems; however, this test can be slightly dangerous, as it carries a risk of miscarriage and limb impairments amniocentesis - A second trimester procedure that involves inserting a syringe into a woman’s uterus to extract a sample of amniotic fluid, which is tested for a variety of genetic and chromosomal conditions. During the second trimester, a safer test, called amniocentesis, can determine the fetus’s fate. The doctor inserts a syringe into the woman’s uterus and extracts a sample of amniotic fluid. The cells can reveal a host of genetic and chromosomal conditions, as well as the fetus’s sex. planned for a gestational age (typically week 14) when there is enough fluid to safely siphon out and time to decide whether to carry the baby to term. carries a small chance of infection and miscarriage, depending on the skill of the doctor by the time the results of the “amnio” arrive, quickening may have occurred. The woman must endure the trauma of labor, should she decide to terminate the pregnancy at this late stage. many doctors suggest that patients over age 35 have these procedures. When these couples receive a diagnosis of serious chromosomal problems, most do terminate the pregnancy—roughly 8 in 10 in one study at a U.S. hospital While a diagnosis of serious fetal problems is devastating to both moms and dads, for women specifically—perhaps because they are carrying the child inside—it may be more traumatic to get this news during pregnancy than at birth I cannot emphasize strongly enough that giving birth to a baby with serious birth defects is rare. E. Infertility and New Reproductive Technologies infertility - The inability to conceive after a year of unprotected sex. Or inability to carry a child to term. In affluent nations, it affects an estimated 1 in 6 couples. In poor countries, the statistics may be as high as 1 in 4. infertility rates have been rising over the past half-century, due to sexually transmitted diseases in the developing world and the fact that so many developed world women today are delaying childbearing to their thirties and beyond Can affect women (and men) of every age, getting pregnant is far more difficult at older ages. Within the first six months of trying, roughly 3 out of 4 women in their twenties conceives. At age 40, only 1 out of 5 achieves that goal many assume infertility is usually a “female” problem. Not so! Male issues—which can vary from low sperm motility to varicose veins in the testicles—are equally likely to be involved Infertility puts stress on both partners but is apt to hit women hardest In one Danish questionnaire study, almost 1 in 3 patients at a male fertility clinic confessed that their condition affected their sense of masculinity and self-esteem The impact varies in intensity, depending on one’s culture. In places like Iran, where not being able to bear a child is sometimes an accepted reason for divorce infertility can leave a woman shunned by family and friends There may be a feeling of being socially isolated, even in the liberal West. Does telling people help? If, and only if, you have a caring, social-support system, you may feel relieved by being upfront But the bottom-line message is that, in coping with infertility, a supportive partner matters most 1. INTERVENTIONS: Exploring ART For females, there are treatments to attack every problem on the reproductive chain from fertility drugs to stimulate ovulation, to hormonal supplements to foster implantation from surgery to help clean out the uterus and the fallopian tubes, to artificial insemination (inserting the sperm into the woman’s uterus through a syringe). Males may take medications or undergo surgery to increase the quality and motility of the sperm. Then there is that ultimate approach: assisted reproductive technology (ART) - Any infertility treatment in which the egg is fertilized outside the womb. Most widely used is: in vitro fertilization - An infertility treatment in which conception occurs outside the womb; the developing cell mass is then inserted into the woman’s uterus so that pregnancy can occur. After the woman is given fertility drugs (which stimulate multiple ovulations), her eggs are harvested and put in a laboratory dish, along with the partner’s sperm, to be fertilized. A few days later, the fertilized eggs are inserted into the uterus. Then waits to find out if the cells have implanted in the uterine wall. A sperm may be injected directly into the ovum if it cannot penetrate the surface on its own. The woman may use a donor egg—one from another woman— in order to conceive. Or, she may go to a sperm bank to utilize a donor sperm. The fertilized eggs may be inserted into a “carrier womb”—a surrogate mother, who carries the couple’s genetic offspring to term a woman under age 35 getting pregnant after 1 round of in vitro treatments was less than fifty/fifty. Over age 42, success rates per cycle slid down to less than 1 in 10 Critics emphasize the headaches (and heartaches) involved in ART; the pain, expense, and the chance of miscarrying if many eggs take the virtual certainty of having fragile, small babies when several conceptions come to term or the issues attached to third-party arrangements: (“Should I meet my egg or sperm donor?” “Do I tell my child this person exists?”) This landmark technology has given thousands of infertile couples their only chance to have a biological child Birth VI. A. Stage 1: Dilation and Effacement 1. This first stage of labor is the most arduous. The cervix must efface and dilate. From about a dime, to a coffee mug or soup bowl accomplished by contractions—muscular, wavelike battering against the uterine floor. contractions start out slowly, perhaps 20 to 30 minutes apart. Even at the beginning of labor, the contractions put about 30 pounds of pressure on the cervix to expand to its cuplike shape. They become more frequent and painful as the cervix more rapidly opens up. Sweating, nausea, and intense pain can accompany the final phase B. Stage 2: Birth The fetus descends through the uterus and enters the vagina, or birth canal. \ As the baby’s scalp appears (crowning), parents get their first exciting glimpse of this new life. The shoulders rotate; the baby slowly slithers out, to be captured and cradled as it enters the world.. C. Stage 3: The Expulsion of the Placenta In the ecstasy of the birth, the final event is almost unnoticed. The placenta and other supporting structures must be pushed out. Fully expelling these materials is essential to avoid infection and to help the uterus return to its prepregnant state. D. Threats at Birth Just as with pregnancy, a variety of missteps may happen during this landmark passage into life: problems with the contraction mechanism; the inability of the cervix to fully dilate; deviations from the normal head-down position as the fetus descends and positions itself for birth difficulties stemming from the position of the placenta or the umbilical cord as the baby makes its way into the world. Today, these in-transit troubles are easily surmounted through obstetrical techniques. E. Birth Options, Past and Present 1. Natural Childbirth For most of human history, pregnancy was a grim nine-month march to an uncertain end Not only were there the hazards involved in getting the baby to emerge, but a raging infection called childbed fever could also set in and kill a new mother (and her child) within days. Women had only one another or lay midwives to rely on during this frightening time. Doctors could not view the female anatomy directly, and were clumsy (using forceps) and unsanitary, spreading childbed fever Techniques gradually improved toward the end of the nineteenth century, but hospitals were full of contagious disease. Then, with the early-twentieth-century conquest of many infectious diseases, it became fashionable for affluent middle-class women to have a “modern” hospital birth. By the late 1930s, fetal mortality plummeted, and birth became genuinely safe In 1997, there were only 329 pregnancy-related maternal deaths in the United States The natural process of birth had become an impersonal event. Women protested the assembly line hospital procedures; the fact that they were strapped down and sedated in order to give birth. They eagerly devoured books describing the new Lamaze technique, which taught controlled breathing, allowed partner involvement, and promised un-drugged births. The women’s movement of the 1960s and early 1970s, the natural-childbirth movement arrived. Natural Childbirth Natural childbirth, a vague label for returning the birth experience to its “true” natural state, is now embedded in the labor and birth choices available to women today. To avoid the hospital experience, some women choose to deliver in homelike birthing centers. They may use certified midwives rather than doctors, and draw on the help of a doula, a nonmedical pregnancy and labor coach. Women who are committed to the most natural experience may give birth in their own homes. Let’s now pause for a minute to look at the last procedure in the table: the cesarean section. 2. cesarean section (c-section) A method of delivering a baby surgically by extracting the baby through incisions in the woman’s abdominal wall and in the uterus. exploded in popularity during the 1970s. By the turn of this century, c-sections accounted for an astonishing 1 in 3 U.S. deliveries Some c-sections are planned to occur before labor because the physician knows in advance that there are dangers in a vaginal birth. If the woman is affluent, she can sometimes choose to have a c-section rather than go through labor on her own. Most occur when there are difficulties once labor has begun. To what degree they are unnecessary, (health care workers fears of legal liability) We don’t know. We do know the best-laid birth plans may not work out, some women can feel upset if they had been counting on “the natural way” the real tragedy is lack of access to high-quality medical interventions in least-developed In 2010, an estimated 287,000 people died of pregnancy-related causes, typically postpartum hemorrhage, infections, or pregnancy blood-pressure complications that would prompt an immediate c-section in the developed world some relatively poor nations have made great progress in reducing maternal mortality, others have lost ground. Perhaps due to its chronic wars, child marriage, and the prevalence of HIV, sub-Saharan Africa had worse maternal death statistics in 2010 than in 1990 billions of developing world mothers-to-be still approach birth with a more basic concern than their Western counterparts. All too often wondering “Will I survive my baby’s birth?” I. The Newborn A. Tools of Discovery Apgar scale - A quick test used to assess a just delivered baby’s condition by measuring heart rate, muscle tone, respiration, reflex response, and color. Newborns with five-minute Apgar scores over 7 are usually in excellent shape. if the score stays below 7, the child must be monitored or resuscitated and kept in the hospital B. Threats to Development Just After Birth 1. Born Too Small low birth weight (LBW) - A body weight at birth of less than 5 1/2 pounds. In 2010, about 15 million babies were born preterm, or premature, more than three weeks early In the U.S., about 1 in every 11 babies are categorized as LBW, weighing less than 5 1/2 pounds. Babies can be designated low birth weight because they either arrived before their due date or did not grow sufficiently in the womb. Aside from factors, such as smoking, uncontrollable influences can cause this too-early or excessively small arrival into life infection that prematurely ruptures the amniotic sac, or a cervix that cannot withstand the pressure of the growing fetus’s weight Ironically, the same cutting-edge procedures discussed earlier, such as c-sections on demand and ART, boost the probability of a baby leaving the womb early and being more frail very low birth weight (VLBW) - A body weight at birth of less than 3 1/4 pounds. vulnerable newborns are the 1.4 % classified as VLBW When these infants are delivered, often very prematurely, they are immediately rushed to a major medical center to the NICU. neonatal intensive care unit (NICU) - A special hospital unit that treats at-risk newborns, such as lowbirthweight and very-low-birthweight babies. more than 1 million babies who die each year because of being very premature Enduring health problems are a serious risk with newborns Study after study suggests low birth weight can compromise brain development It may impair preschoolers’ growth and motor abilities It can limit intellectual and social skills throughout childhood possibly promoting overweight and early age-related disease Astronomical sums are required to keep frail babies alive—expenses that can bankrupt families and are often borne by society as a whole When a child is born at the cusp of viability—at around 22 weeks—doctors, not infrequently, refuse to vigorously intervene survival rates vary, depending on the individual baby and access to high-quality care due to dramatic neonatal advances during the l980s, many more small babies are now living to adulthood unimpaired C. The Unthinkable: Infant Mortality In the developed world, prematurity is the primary cause of infant mortality In affluent nations, infant mortality is at an historic low The dismal standing of the U.S. compared to many other industrialized countries, rank a humiliating forty-sixth in this basic marker of a society’s health
