The third trimester is a time of steady growth as your baby matures
and gets ready for birth. As your baby gains weight, fat is stored
under the skin. This smoothes your baby's skin and makes your baby
During the beginning of this trimester, you may feel plenty of
kicks, squirms, flips, hiccups and other movements in between
quiet periods. Your baby starts having regular sleep and wake
cycles, and you will notice the difference in activity. You may
also notice your baby responding to bright light as well as
Although many people consider pregnancy to last nine
months, it is actually 280 days, measured from the first
day of the last menstrual period, or 40 weeks. The "due date" is
day 280 or the end of the 40th week.
By the 28th week your baby has eyelashes,
and his hair is growing. His fingernails have grown to the end of
his fingertips. The lanugo, the downy hair, is beginning to
disappear. This is also the start of dramatic brain growth that
will continue for your baby's first two years.
Your baby's lungs are beginning to reach maturity, meaning your
baby would have a good chance of surviving if born now. Your baby
is about two pounds and is about 13 inches from crown to rump.
At 32 weeks your baby has grown so much that there is much less
room to move around. You can feel the difference in your baby's
movements, which are more like wriggling and twisting.
Your baby may settle into a favorite position. That can make it
easier to identify his feet, elbows and hands when these push
against the wall of your uterus. The vernix coating on your baby's
skin is beginning to be absorbed.
Starting in week 36, your baby gains about half a pound and
grows half an inch a week. Many babies turn head-down and stay in
that position for birth.
First babies are likely to settle into the
mother's pelvis at about week 38.
This act of the head engaging in the pelvis is called
lightening. It makes your breathing easier but creates pelvic
pressure. If this is not your first baby, your baby's head may not
engage until you go into labor.
After week 37, your baby is considered "term," which means
fully-grown. Term babies often weigh 7 to 8 pounds and are 18 to 21
inches long, measuring from crown to rump.
Baby's hair is longer. Eyelashes and eyebrows are very
open and sensitive to light. Baby is about 15 inches long and
weighs about 3 pounds.
Baby gains about 7 ounces a week.
Taste buds develop. All of baby's senses are developed.
Vernix (a creamy coating on the skin) and lanugo (the fine hair
that covers the baby's body) begin to disappear. Baby's head is
more in proportion to the body.
Skin is less wrinkled, but
baby is still thin. Baby is about 18 inches long and weighs about 5
Baby's movements can be seen on the outside of the mother's
Skin is becoming more pink. Baby is blinking.
Fingernails and toenails have grown to the end of baby's fingers
organs are now mature. Skin is red but smooth. Baby is about 19
inches long and weighs about 6 pounds.
Deposits of fat continue to form. Baby is considered
Baby gains 1 ounce a day. Baby may move down into pelvic
Fine hair remains only on arms and shoulders. Fingernails are
now beyond the ends of fingertips.
Baby is fully developed. Baby is about 20 inches long and weighs
7 to 8 pounds.
Allina Health's Patient Education Department, Beginnings: Pregnancy, Birth and Beyond, seventh edition, ob-ah-90026
Allina Health's Patient Education Department experts