The Developing Baby
Human Development: Prenatal-Toddler
Conception
 Ovum: an egg cell
 Ovulation: an egg cell is released by one of a woman’s two
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ovaries.
Uterus: the organ in a women’s body in which a baby
develops during pregnancy.
Fallopian Tube: connects the ovary to the uterus.
Sperm: male cell.
Conception: a male cell reaches the Fallopian tube; it may
penetrate and fertilize the ovum.
Prenatal Development
 Prenatal Development: the baby’s development during a
pregnancy.
 Grouped into three stages: germinal stage, embryonic stage,
and fetal stage.
The Germinal Stage
 Zygote: fertilized egg.
 Cell Division
 While the zygote is still in the Fallopian tube, it begins to
grow by cell division.
 Single cell splits into two cells, then the two cells rapidly
multiply to four, eight, then so on.
 Implantation
 Lining of the uterus has thickened enough to provide a place
for the zygote to attach itself and continue to grow.
 Zygote usually implants in the lining of the uterus and is
covered over by that lining.
 Despite the rapid growth of the zygote during the two weeks
after fertilization, it is only the size of the head of a pin.
Embryonic Stage
 Embryo: the developing baby is called from about the
third week of pregnancy throughout the eighth week.
 During this stage that several important and amazing
changes occur.
 Organs and Body Systems
 The cells begin to separate and develop into the major systems of the
human body.
 27 days after conception the neural tube, has closed.
 The developing brain is sensitive to damage from any drugs or alcohol the
mother might take.
Embryonic Stage
 Amniotic Sac
 Amniotic Fluid: protects the developing baby.
 Formed from special layers of cells in the uterus.
 Cushions the embryo from any bumps or falls that the mother
might have.
 Embryo is still very small and can float freely in the amniotic fluid.
 The Placenta and Umbilical Cord
 Placenta: formed from special layers of cells in the uterus.
 It is rich in blood vessels and attached to the wall of the uterus.
 Umbilical Cord: connects the baby to the placenta.
 The umbilical cord takes carbon dioxide and other waste products
away from the baby and to the placenta, which releases those
wastes into mother’s bloodstream.
 Third and final stage of development is the longest.
 Begins around the eighth or ninth week of pregnancy and
Fetal Stage
lasts until birth.
 Making Movements
 During the fourth and fifth month, the kicks and other movements of the
fetus touch the wall of the uterus.
 Can feel similar to fluttering.
 Gradually, sensations become stronger and more frequent.
 Completing Development
 During the last few months of pregnancy, development continues,
preparing the fetus to live independently.
 Body’s major organs become ready to function without and help from the
mother’s body.
 Fetus gains weight rapidly, begins to look more “baby-like.”
Fetal Stage
 Staying Active
 Fetus can do surprising number of things—suck its thumb, cough, sneeze,
yawn, kick and hiccup.
 Fetus can even cry.
 Even though the fetus is still very active and can change positions.
 Growing Bigger
 The uterus also expands, causing the woman’s abdomen to grow.
 Fetus grows large during the last few months of pregnancy, no longer has
room to stretch out.
 Fetal Position: fetus curls up inside the uterus.
Preparing for Birth
 Pregnancy is about 40 weeks, or 280 days, from first day of
the last menstrual cycle.
 Fetus is fully developed and can usually survive outside the
mother’s body without a great deal of medical assistance.
 Some babies are born either a few weeks early or a few
weeks late.