The Concept of Reproduction Pt. 1
Pelvis
★ Two unique functions
○ Support and protect the pelvic contents
○ Form the relative fixed axis of the birth process
★ The pelvis is where the baby passes during labor and delivery. We need a good pelvis for
the mom to deliver vaginally !!
★ Four Bones:
○ Two innominate bones: Ilium, Ischium, Pubis
■ 2 innominate bones – innominate because its 3 bones fused together. Three
bones fuse together and join together at the symphysis pubis
○ Sacrum and Coccyx aka tailbone
■ Two Organs in the Pelvis: Bladder, Uterus
★ Engagement – during last trimester of pregnancy or during birth when the baby head is
coming down the pelvis
★ Inlet – entrance of the basin or pelvis
★ Pubic arch
○ Important because how large it is or how narrow it is going to affect the delivery
process
★ Pelvic outlet – exit from the pelvis during birth, the tailbone moves backwards and
sometimes breaks during delivery
★ Relaxin – hormone during pregnancy that relaxes the body in preparation for labor
★ Sacral promontory – upper anterior part of the sacrum (landmark for pelvic
measurement and five vertebrae)
○ Indicates the woman has a really good pelvis for vaginal delivery !
Pelvis: Important Landmark
● Symphysis pubis – joint of 2 pubic bones
○ Has fibrocartilage and can be both superior/inferior pubic ligaments
○ Important that the inferior ligament stretches first from delivery and pregnancy,
making it easier for pregnancies that follow (makes 2nd pregnancy easier)
● Pubic arch – triangle below the symphysis
○ Very important due to baby passing through here, Need good arch
● Sacroiliac joint – degree of mobility that increases nearing the end of pregnancy
○ Pelvic outlet (exit) can increase to 1.5 - 2 cm while doing squatting position
○ Lithotomy position during delivery (lying on back with legs up and apart)
○ Makes angle wider so the baby can come out
● Sacrococcygeal joint – relaxes and increases room for the baby
● Ischial spine (diameter #2)
○ Inner protuberance of ischial bones → Short Diameter → Fetal station landmark
○ Shortest diameter in the pelvis and fetal station landmarks
○ Baby head should be flexed with their face against the chest to help with fitting
through pelvis
● Transverse diameter – for a normal female pelvis (13.5 cm)
○ As the baby is going down, because we see the ischial which protrudes inwards,
the ischial spine makes this diameter shorter (look @ diameter #2 – makes the
area 10.5 cm)
○ Landmark ZERO “Station”
■ During labor when the baby is descending, they have to pass the narrow
gate (ischial spine) aka “station zero”
● Station – helps us see how the baby is descending during labor
○ If the baby has a negative station number, it is higher up in the abdomen and as
the uterus contracts it pushes baby through birth canal
○ If the baby passes zero and the cervix has dilated with complete effacement, then
it is time for mom to push !!
■ Top – negative numbers -2 etc
■ Middle – zero
■ Below – positive numbers +1, +2 etc
True Pelvis
★ Has three parts:
○ Pelvic inlet: Engagement
○ The pelvic cavity
○ Pelvic outlet
Pelvic Measurements Continued .
● Transverse diameter at the inlet – 13.5 cm
● Whenever the baby gets to the ischial spine – 10.5 cm
● Whenever the baby flexes its head against its chest, a normal sized head is around 9.5 cm,
allowing the baby to squeeze through
○ Head Must be Flexed !! Head Should Face Mom Back !
True Pelvis
★ The pelvic outlet:
○ The outside of the pelvic cavity Antero-posterior diameter increases during birth
and tailbone moves backwards
○ Has increased mobility of sacrococcygeal joints due to the hormone Relaxin
○ Can break with abnormal presenting parts
★ Pubic arch – fetus passes under during birth (possible dystocia)
★ Shoulder Dystocia – requires special intervention and if it doesn’t work, the mom will
need a Cesarean
Pelvis Types
● Gynecoid: Good for vaginal birth
○ Transverse diameter is good. Anterior-posterior diameter is good. Inlet is good,
Outlet is large. Half of women have this shape
● Android: Heart shaped (not good for vaginal birth and has short outlet)
○ Outlet is short. Narrow pubic arch. Define need for C-section
● Platypelloid: Flat pelvic (cesarean)
● Anthropoid: Oval shape (may be okay for vaginal birth)
○ Anterior-posterior diameter is a little short. Outlet is okay. Vaginal delivery is
possible but can be difficult
Pelvic Floor
★ The muscular pelvic floor:
○ Overcomes the force of gravity
○ Supporting structure
★ The pelvic diagram – exceptional capacity of dilation during birth, returns to
prepregnancy state after birth (overstretch to get baby out and goes back together after)
Female Reproductive Cycle
● Neurohormonal Control
○ Hypothalamus → Anterior pituitary → Ovaries → Uterus Endometrium
● Hypothalamus
○ GnRH (Gonadotropin Releasing Hormone) → Anterior pituitary → FSH (Follicle
Stimulating Hormone) and LH (Luteinizing Hormone)
○ Works on anterior-posterior which sends signals to the ovaries and the ovaries
affect the uterus and endometrium
● Need good symmetry – Patients with spinal issues (ex. scoliosis) can have a difficult
time with vaginal delivery. High risk for multiple doses of the epidural because they are
unsure where the spine is. High chance that the epidural will only numb one side of the
body or below the knee !!
● FSH and LH
○ Anterior pituitary produces FSH and LH (without these two hormones, the eggs
do not mature and there won’t be ovulation)
○ Follicle Stimulating Hormone – female eggs are kept in follicles. During
ovulation, the egg goes down the fallopian tube while the follicle stays in the
ovary. All girls are born with all the eggs they need. They are silent until puberty.
Then during puberty this hormone says “lets start!” FSH is going to stimulate this
follicle to grow by producing estrogen. Once the follicle grows, it is going to
produce its own estrogen which starts & continues to grow. When the follicle is
mature enough, it is going to become a fluid filled cavity and then the egg is
released through the ovary wall and the follicle stays there and transforms
○ Luteinizing Hormone – in charge of ovulation and causes the follicle to
transform and produce progesterone
● Corpus luteum – produces progesterone
● Progesterone – Hormones that cause the endometrium to cushion. Because every month,
the endometrium and uterus is prepared to receive a baby.
Female Reproductive Cycle Continued.
★ Ovaries produce gametes and hormones (estrogen, progesterone, testosterone)
○ Estrogen – growth of endometrium
○ Progesterone – enhances the folding and growing
★ Endometrium changes under influence of hormones
○ Endometrium – inner layer of uterine
★ Cycle can go between 24-35 days (some women are regular, some are not), Cyclic
pattern can extend over 30-40 years
○ Each month, one or more eggs (oocytes) are released from the ovaries !!
Female Hormones
● Estrogen
○ Causes uterus to increase in size and weight
○ Expands blood supply
○ Increases myometrial activity
○ Increase uterine sensitivity to oxytocin
■ Decreases excitability of hypothalamus and can increase sexual desire
○ Inhibits Follicle Stimulating Hormone (FSH) production and Luteinizing
Hormone (LH)
■ Estrogen can cause the cervix (lower part of the female reproductive
system that looks like a cylinder) to produce thick and viscous discharge
● Progesterone
○ Secreted by corpus luteum
○ Often called hormone of pregnancy due to its effects on uterus allows pregnancy
to be maintained
■ Without progesterone pregnancy cannot be maintained. During pregnancy
the progesterone supply is on demand
■ Sometimes moms will experience vaginal bleeding during pregnancy due
to low progesterone and will be given an injection of progesterone !!
■ Prior to ovulation, progesterone will spike !
○ Prepares breasts for lactation
○ Vaginal and cervical changes
■ Causes vaginal discharge to be loose and elastic (can stretch 5 cm) some
women use this as means on contraception (time for ovulation)
○ Progesterone relaxes everything. Besides cushioning the uterus, everything
relaxes to prevent contractions. Also will relax GU and GI
■ What happens if the GI is relaxed? Causes constipation. Pregnant
women are at risk for constipation
■ What happens if the GU is relaxed? Can cause urinary retention. This is
bad, we want the bladder to contract
● Prostaglandins (PGs)
○ Produced by cells of endometrium
■ Without prostaglandins, we wouldn’t ovulate because prostaglandins help
the ovary membrane to relax and stretch so that the egg can be expressed
from the ovaries
○ PGE relaxes smooth muscles, potent vasodilator
○ PGF potent vasoconstrictor, increases contractility of muscles and arteries
○ PGE and PGF:
■ Increases during follicular maturation
Ovarian Cycle
★ Follicular Phase (1-14 days)
○ FSH → Maturity of follicle → Graafian follicle (fluid filled cavity)
○ Graafian follicle – follicle that is ready. The egg is ready to be expelled. The
fluid doesn’t do anything. It maintains the mature oocyte (egg). After the egg is
gone, the fluid disintegrates somewhere in the body
★ Luteal Phase (15-28 days)
○ Ovulation (LH influence) around day 14
○ Follicle change → Corpus Luteum (degenerates in 8 days)
○ Fertilization → HCG (Human Chorionic Gonadotropin) → maintains corpus
Luteum → Progesterone
★ Newborn girls are born with all of their eggs. They are silent until puberty and when the
hormone FSH and LH start
★ Ovulation – the egg is growing. This is called an oocyte. This then goes to the fimbria.
The fimbria is the end of the fallopian tube and the fimbria catch the egg
★ If there is no pregnancy, the corpus luteum is going to degenerate in 8 days. Whenever it
degenerates, there is no progesterone; the endometrium is going to shed off and create the
menstrual cycle
★ If there IS pregnancy and the egg meets the sperm, and the egg is fertilized, the fertilized
egg is going to keep this life !! The fertilized egg is going to produce the hormone HCG
(Human Chorionic Gonadotropin). This is the hormone that is tested in urine & blood
to say that you are pregnant
○ HCG keeps the corpus luteum alive and progesterone on demand until week 11
whenever the placenta takes over and produces progesterone until birth. Corpus
luteum until the placenta takes over. We need progesterone on demand during
pregnancy !!
○ Whenever we test urine or blood we are testing for HCG. HCG peaks whenever
the egg is fertilized (pregnancy)
Female Reproductive Cycle Continued.
● Ovulation:
○ Mid Cycle pain (mittelschmerz or cramping)
■ Can be comfortable or uncomfortable based on the person, caused by
ovarian membrane rupturing (peritoneal reaction that causes pain)
○ Vaginal discharge (mid cycle spotting)
■ Can confuse some people because they think it is their period but it is
spotting and they are pregnant
○ Change in body temperature (0.5-1 F) 24-48 hrs after ovulation
○ Ovum fertile for 12-24 hrs
■ Natural Conception – people do not have sex for four days before
ovulation and five days after
■ Sperm lasts 48 hrs waiting for the egg
■ After the egg is fertilized, it reaches uterus in 7-96 hrs
● Stretchy discharge = Time for ovulation !!
○ LH peaks during ovulation and is in charge of ovulation
● Uterine Cycle
○ Menstrual – lasts two to eight days and blood loss can be between 25-60 ml
■ Women lose iron, 0.5-1 mg per day (during menses eat iron rich foods)
○ Proliferative – growing of the endometrium
○ Secretory – grows with vessels and if it is not fertilized, this is degraded and the
endometrium sheds again
● In the luteal phase – the egg is gone during ovulation. The corpus luteum is producing
progesterone. It is going to degrade within 1 week. Fertilization is what is going to keep
the egg alive because of HCG. In the uterus there is some change. We start with
ovulation, and you can see with menstruation the uterus is going to shed. Progesterone is
down, its really low. FSH is going to stimulate the follicle to grow again and then they
produce estrogen that is going to cause the endometrium to grow. You can see the vessels.
● The day prior to ovulation, progesterone peaks. The endometrium then cushions with so
many vessels
○ Implantation – after fertilization, the egg burrows into the endometrium
○ Window of Fertilization – five days prior to ovulation and four days after when
egg meets the sperm
Conception and Embryonic Development
★ Mitosis – one cell divides into 2 dura cells with the same chromosomes
○ 1 cell in our body has 46 chromosomes that impact DNA
★ Meiosis
○ Whenever it comes to sperm and egg (gametes), do not divide by mitosis but they
do by meiosis
★ Gametogenesis
○ XX – Girl
○ XY – Boy
■ The 23rd chromosome determines the sex of the baby !!
★ The oocyte is going to produce 2 dura cells. One is going to be a useless cell for our
body. The 2nd division happens after fertilization. It is going to produce 3 cells in our
body that are useless. They are going to vanish in our body. We are going to have 1
mature ovum which is going to have half of the chromosomes (23). The egg is the only
cell in our body that is going to have half of the chromosomes. The sperm is going to
have 23 chromosomes. During fertilization, the sperm has 23 chromosomes, the egg has
23 chromosomes. This creates 46 chromosomes. The female has 23 X chromosomes and
the last chromosome is the sex chromosome
Fertilization
● The two sex chromosome of the 23rd pair determines the sex:
○ XX (female) or XY (male)
● Fertilization → Ampulla (1/3 Outer of the fallopian tubes)
○ The egg is released and travels as it divides and then fertilization happens
○ Many sperm rush to meet the egg but only one meets the ovum. The egg fertilized
is going to keep the corpus luteum alive to produce progesterone. After the egg is
fertilized it will divide while traveling to go to the endometrium for implantation
(when the egg dips down into the endometrium)
○ Fertilization happens at the 1/3 Ampulla !!
● The vagina has an acidic pH (during ovulation because of hormones and progesterone
the vagina will become less acidic which in turn helps the sperm). If the sperm gets to the
vagina and it is too acidic, the sperm will die. Prior to ovulation, the environment of the
vagina becomes less acidic
Twins
★ Occurrence: 30 in 1000 pregnancies
★ Delayed childbearing, use of artificial reproductive treatments
★ Fraternal (dizygotic)
○ Separate placentas that happens during ovulation
○ 2 or 3 eggs grow to maturity at the same time and then two people are conceived
at once. There will be 2 corpus luteum and there has to be enough progesterone
for two twins
★ Identical (monozygotic)
○ One placenta
○ 1 egg is released and fertilized. During division they will separate into 2 (one egg
that splits into 1/2)
Pre Embryonic Development
● Preembryonic Stage → 14 days after fertilization
○ 2 Phases: Cellular multiplication and Cellular differentiation
○ A baby in utero is surrounded by two membranes (one inside is amnion and
outside is chorion)
○ Early Pregnancy Factor (EPF) → 24-48 hrs after fertilization
■ During early stage pregnancy a test can be done, Early Pregnancy Factor
ECF, that is produced by trophoblast cells to tell pregnancy
■ After a month without a menstrual period a test can be done to check HCG
in blood and urine
● Whenever the sperm is fused with the egg, it becomes 1 cell. This is called a zygote. The
zygote is going to travel and divide into 2 cells → 4 cells → masses of cells (morula).
Then we start cellular multiplication and cellular differentiation. The cell is going to
differentiate into some membrane tissue. Blastocyst is going to become amnio in the
amniotic membrane (the one inside). The trophoblast is going to become the placenta
and everything else. Sometimes the client does not know they are pregnant at this point !
They may not have any symptoms yet !!
Pre Embryonic Development Continued.
★ Amniotic Fluid (estrogen and hormones produce)
○ Cushions and maintains temperature
■ Yolk Sac – formed during pre embryonic development and is in charge of
RBCs in the first days of life but will vanish
○ Symmetric growth prevents adherence of embryo-fetus to amnion
○ Allows umbilical cord to be free of compression (22 inches)
■ Umbilical cord has three vessels as in two arteries (bring blood back to
placenta) and one vein (good blood flow from placenta to the baby)
○ Fetal extracellular space
○ Swallowing and excretion
○ Used for tests – Trophoblasts is gonna develop into the chorionic villi (beginning
of placenta formation). Collects chorionic villi sample to test for congenital
abnormalities
■ Polyhydramnios – when there is too much amniotic fluid is more than
2000 ml causing the uterus to stretch and postpartum hemorrhage
■ Oligohydramios – less than 500 ml causing cord compression, adherence
of membrane to the baby and cord prolapse, putting baby in critical
condition
○ Other risk for PPROM – premature rupture of membrane
■ Infection of membrane
■ Bleeding
★ Placenta
○ Maternal-fetal gas exchange
■ Baby does not breathe inside mom. It breathes through mom. The fetal
lungs are in silent mode. They don’t do anything. There is no O2, CO2
exchange. The mom does everything !!
○ Maternal/Fetal side – side that attaches to the endometrium, after the baby is born
there is a wound inside the mom (need uterus to contract and vasoconstrict, heals
in about two weeks)
★ Umbilical Cord
○ Wharton Jelly – protects the umbilical cord
○ Two arteries and one vein
Placenta
● Placental functions:
○ Fetal respiration, perfusion, nutrition and excretion
○ Metabolic activities
○ Transport
■ Blue – Arteries, brings bad blood from the baby to the placenta
■ Red–Veins, brings good blood from placenta to the baby
○ Endocrine
■ HCG → Progesterone and Estrogen
■ Human Placental Lactogen (HCL) – growth hormone for the baby and
glucose that the baby uses for energy
○ The pregnant body always tries to compromise moms function to take care of the
baby. Moms body is going to keep blood sugar inside the blood. Sugar because of
insulin is uptaken into the cell and is changed into ATP for the muscles and the
liver. The body keeps normal glucose (70-100). During pregnancy, the pregnant
body tells insulin to not touch glucose because the baby needs glucose. When
maintaining storage of glucose in the blood this can kill mom because there is too
much glucose in the blood. But the body makes sure we have enough glucose for
the baby BECAUSE of HPL (HPL antagonizes insulin). It competes with insulin
receptors and tells them not to take all of the glucose. We need it for the baby!
This causes insulin resistance to make sure there is enough insulin for the baby.
This is what can cause gestational diabetes !!!!!
● Corpus luteum is kept alive for 11-12 weeks to produce progesterone. After that the
placenta takes over !!
Fetal Circulation
★ Vein (red) brings blood to baby and baby now has circulation
★ Whenever the blood needs reoxygenated, the two arteries are going back to the placenta
★ Most of the blood bypasses fetal lungs (placenta assumes lung function)
○ Ductus Venosus: umbilical vein → inferior vena cava (bypass liver)
○ Foramen Ovale: right atrium → left atrium (skin right ventricle)
○ Ductus Arteriosus: pulmonary artery → aorta (bypasses lungs)
■ After your blood goes to the lungs, because the lungs are in silent mode,
they are not giving any respirations or O2. Blood is going to cross the
pulmonary artery to the aorta. There is another connection. When 2
arteries are mixed we call that ductus arteriosus → rest of body
★ In our circulation, does the blood from the right side mix with blood from the left side ??
NO. BUT for the baby it DOES !!
○ For our circulation, we have blood coming from inferior vena cava to the right
atrium to the right ventricle to the lungs and then we have blood coming from the
lungs to the left atrium into the left ventricle, then the left ventricle pumps it to the
rest of the body
★ For the baby we have the umbilical cord (red one) which is bringing good blood from the
placenta which goes inside the baby. The umbilical cord is going to connect to the baby’s
inferior vena cava. We call this ductus venosus (two veins connect). It is going to go to
the right atrium. This blood should come to the right ventricle and a little bit will come,
but the blood crosses. There is no wall between the 2 atriums. Wall is called the foramen
ovale. This is not closed, but usually closes within 24hrs of being born. This is why when
you are first auscultating a baby’s heart, sometimes you might hear a murmur early on.
Embryonic Development
● Pregnancy lasts on average of 40 weeks (280 days)
● Most fetuses born within 10-14 days of estimated date of birth (EDD)
● Whenever we are getting the due date, we start from the first date of the menstrual
period !! Ovulation happens 2 weeks after and fertilization happens after (this is why the
baby can be born within that 2-week period)
● Preembryonic Stage
○ At this point if the pregnant client eats or drinks or exposed to anything harmful
to baby it is dangerous for first 14 days
○ Teratogens – anything that can compromise, prevent or become harmful to the
development of the baby.
■ Ex: alcohol, tobacco, pesticides, cytotoxic drugs, x-ray (everything is still
harmful because the placenta is a barrier but during the embryonic stage, it
is not formed yet)
○ Cytotoxic drugs – antidepressant, antipsychotic, anti anxiety medications
● Embryonic Stage
○ Day 15 until 8th week
○ Tissues differentiate into essential organs
○ Embryo most vulnerable to teratogens
● Fetal Stage
○ From end of 8th week (fetus) to end of 37th week
○ Every organ system and external structure found in the full term newborn is
present
● Three Trimesters
○ 1st trimester – week 1 to week 13
○ 2nd trimester – week 14 to week 26
○ 3rd trimester – week 27 to birth
Fetal Development
★ 8 Weeks through terms
○ Term @ MWH: 37 0/7 weeks
○ Pearson = 38-40 weeks
○ Folic acid – prevents neural tube defects and all child bearing age women should
take folic acid
★ 20 Weeks
○ Gender can be identified, mother feels movement (quickening is a little earlier
18-20 weeks for prime, 14-18 weeks for multiple)
○ Someone with multiple pregnancies might feel baby at 16 weeks !!
○ Fundus is @ level of umbilicus
★ 24 Weeks
○ Viable (will resuscitate), Vernix starts to form
○ Venix = white cheesy cream on baby body
★ 34 Weeks
○ Lungs are mature and less of a chance of requiring intubation at birth
○ NICU admission required at MWH up until 35 weeks
○ Xiphoid process – baby is sitting @ 36 weeks
○ Surfactant – what we have in our alveoli that prevent our alveoli. from
collapsing. Baby produces surfactant at 35 weeks !!
★ 37 Weeks
○ Term fetus and newborn nursery if stable
○ Lanugo and vernix present at birth
★ After 41 Weeks
○ Considered postterm
★ Perterm
○ In antepartum, if the mom has a complication, we want to try to wait until the
mom is at 35 weeks to deliver, so that the baby doesn’t experience respiratory
distress. Without surfactant, the alveoli can collapse. In that case, sometimes they
give the baby medication to produce surfactant !!
■ Medication they give the mom for the baby to produce surfactant faster
because we are expecting the baby to be born before 35 weeks –
BETAMETHASONE. This is given twice as IM injection !!!
○ Premature = More Vernix
★ The baby can weigh…
○ Normal weight – 6 lb 10 oz– 7lb 15 oz.
○ Smaller than gestational age – smaller than 6 lb or 2500 g (we have to monitor
them for blood sugar)
○ Larger than gestational age – 8lb and above (sometimes born to clients with
diabetes, or it could just be genetic)