$Unique_ID{PAR00402}
$Pretitle{}
$Title{Pregnancy:  The First Month:  Your Growing Baby}
$Subtitle{}
$Author{
Editors of Consumer Guide
Ellis, Jeffrey W
Ellis, Maria}
$Subject{First Month Growing Baby Conception conceive egg ovary ovaries
fertilize fertilized sperm menstrual period characteristics sex hair eye color
blood type fallopian tube tubes uterus embryo placenta amniotic sac}
$Log{
Your Growing Baby (First Month)*0040201.tif
28-Day Embryo*0060201.tif}

Miracle of Birth


The First Month:  Your Growing Baby


     Conception occurs when an egg from your ovary is fertilized by a single
sperm.  This process usually takes place about two weeks after the start of
your last menstrual period.  The result of this union of an egg and a sperm is
a single cell--the beginning of your baby.  Even at this earliest stage of
development, all of your baby's characteristics--sex, hair color, eye color,
blood type, and so on--have been determined.
     The egg and sperm unite within the fallopian tube, the four-inch long
passageway that connects the ovary to the uterus.  Within hours, the
fertilized egg begins to divide and slowly floats toward the cavity of the
uterus.  In a matter of days, the fertilized egg--which is now a tightly
packed cluster of many cells--fastens itself to the wall of the uterus to
obtain nutrients and shelter.  It is within the uterus that your baby grows
and develops during pregnancy.
     Once implanted in the wall of the uterus, this tiny mass of cells, now
called an embryo, begins dividing into new cells that will eventually form all
of the organs of your baby's body.  Each of these new cells is unique; each
has a special mission.  Some of the new cells go on to form your baby's heart,
while others are destined to form her brain, liver, kidneys, stomach, and
other organs.
     As these first cells continue to increase in size and number, great
changes take place.  Some of these cells begin to burrow into the wall of your
uterus to form the placenta.  This amazing organ--also called the
afterbirth--will soon be attached to your baby via the umbilical cord and will
provide a vital link through which oxygen and nutrients from your body are
transferred to your baby.  (Before the fertilized egg implants in the uterine
wall, the baby's cells obtain most of their nourishment from the fluids within
the fallopian tube.  After implantation, a balloonlike structure called the
yolk sac forms to supply nourishment to the developing embryo until the
placenta is developed enough to take over this role.)
     Within a few more days, a tiny water-tight sac--called the amniotic sac
or "bag of waters"--forms around your developing baby and gradually fills with
clear fluid.  This amniotic sac cushions the growing baby from shocks while at
the same time allowing her to move around freely--raising her arms and even
doing flips.
     One month after conception, the original fertilized egg has undergone
many dramatic changes.  Your growing baby is now nearly 10,000 times larger
than the single cell from which she came.  Her tiny developing body has a
head, as well as small buds that will become her arms and legs.  Though she is
only about a quarter of an inch long, her face is beginning to form and tiny
dark circles appear where her eyes will be.  Her mouth, lower jaw, and throat
also begin to develop.
     Internally, your baby is starting to develop organs that, in the next few
months, will grow and eventually begin to function.  During the first month of
development, cells in different parts of the baby's body begin to form her
lungs, kidneys, liver, and brain.  A small tube that will become the baby's
heart forms, and by the end of the month, it actually starts beating, although
far too faintly to be heard by you or your doctor.