Fetal Growth and Development
Over the next nine months, a baby will grow and develop inside your body, undergoing the most dynamic changes of its life. During this time of growth, it is important that you maintain a happy, healthy, and active lifestyle.
First Trimester
During the first trimester, your baby is a bundle of cells that are dividing
at an extraordinary speed. Thus, it is imperative for expectant mothers
to avoid anything that could be harmful to this early developmental process.
Women should increase their intake of folic acid six to eight weeks before
conception, if possible, and through the duration of the first trimester.
Folic acid is critical during this time, as it helps to prevent neural
tube defects such as spina bifida.
At the moment of conception, your baby's genetic makeup is complete.
The DNA from the egg and sperm have united and determined your baby's
height, hair color, eye color, etc. The head and trunk of the fetus begin
forming by the fifth week, along with all the major organs. In fact, your
baby's heart will begin beating in the first month!
Arms and legs begin to form, and fingers become distinct. The start of
tiny lips can be seen, and eyelids form, but they remain closed for a
few more weeks. During the first trimester your baby's eyes will take
on the color they will carry throughout life, though the pigmentation
process may not be complete until after birth. Soft nails grow on miniscule
fingers and toes, and teeth buds form along tiny gum lines.
During the middle of the first trimester, your baby's kidneys begin
to secrete urine, supplying the first of the fluid that will fill the
amniotic sac. The amniotic sac is the fluid-filled 'bubble' that surrounds
your baby during pregnancy.
By the end of the first trimester, your baby has taken on a human appearance.
It has bones and muscles that surround the brain and spine, and the reproductive
organs are developed (external genitalia will come later). Though they
cannot make sounds, the vocal cords are also present. All the vital organs
are formed, so now it's time for growing!
Second Trimester
While the first trimester consists of your baby developing body parts,
the second trimester is filled with the growing and maturing of organs.
Your baby can bend its neck, arms and legs, and has developed its sucking
reflex so that now, if it can find its way, it has the ability to suck
its thumb. You will feel lots of movement during the second trimester,
as your baby has learned to move around, kicking and responding to the
sound of your voice. Babies also learn to swallow during these months.
At about a pound and a half by the end of the second trimester, your
baby is developing more fat tissue. With regular periods of wake and sleep,
you may be able to tell your baby’s sleeping pattern by the periods
of movements you feel. Sexual differences become more recognizable during
this time and, for girls, the eggs that they will carry throughout life
have begun to develop. Lashes and brows are now growing around your baby’s
eyes.
Although the organs are well developed, they are not yet functional on
their own. Lungs begin to slightly inflate to prepare for breathing in
the next few months. By the end of the second trimester, you can hear
your baby’s heart beat with a stethoscope.
Third Trimester
The third trimester is a period of fattening up for your baby, as it gains
about an ounce a day. Baby can now open and close its eyes and even hiccup
and cry. Fingernails are so long now that the baby can actually scratch
itself! Your baby will begin to kick vigorously, and usually will turn
its head down in preparation for delivery. For boys, testicles have descended
from the scrotum. Its brain begins to fold and become wrinkled, allowing
more space for nerves to develop.
Babies can live if born during the third trimester, but they need help
breathing and will require extra medical attention. During the last month
of pregnancy, your baby will gain about two pounds.