The end of your pregnancy is near! By now, you're likely eager to meet your baby face to face. But there's still a lot happening to the baby, called a fetus, during the last weeks of pregnancy. Use this information to follow along with what's going on during the third trimester week by week.

As you track your pregnancy, remember that to find your estimated due date, your healthcare professional counts ahead 40 weeks from the start of your last period. That means you're actually not pregnant the first week or two of what's counted as your pregnancy's 40-week timeline.

Twenty-eight weeks into pregnancy, or 26 weeks after conception, your baby's eyelids can partially open. The central nervous system can control body temperature. It also can trigger breathing movements, which can be seen on an ultrasound.

By now, your baby might be nearly 10 inches (250 millimeters) long from the top of the head to the bottom of the tailbone, called crown to rump, and weigh about 2 1/4 pounds (1,000 grams).

Twenty-nine weeks into your pregnancy, or 27 weeks after conception, your baby can kick, stretch and make grasping movements.

Thirty weeks into pregnancy, or 28 weeks after conception, your baby's eyes can open wide. Your baby might have a good head of hair by this week. Red blood cells form in the bone marrow.

By now, your baby might be more than 10 1/2 inches (270 millimeters) long from crown to rump and weigh nearly 3 pounds (1,300 grams).

Thirty-one weeks into pregnancy, or 29 weeks after conception, your baby has finished most major development. Now it's time to gain weight quickly.

Thirty-two weeks into your pregnancy, or 30 weeks after conception, your baby's toenails are visible.

The layer of soft, downy hair that has covered your baby's skin for the past few months, called lanugo, starts to fall off.

By now, your baby might be 11 inches (280 millimeters) long from crown to rump and weigh about 3 3/4 pounds (1,700 grams).

Thirty-three weeks into pregnancy, or 31 weeks after conception, your baby's pupils can change size in response to light. Bones are hardening, but the skull still is flexible and soft.

Thirty-four weeks into your pregnancy, or 32 weeks after conception, your baby's fingernails have reached the fingertips.

By now, your baby might be nearly 12 inches (300 millimeters) long from crown to rump and weigh more than 4 1/2 pounds (2,100 grams).

Thirty-five weeks into pregnancy, or 33 weeks after conception, your baby fills most of the space in the amniotic sac and has less room to move. But you'll probably still feel lots of stretches, rolls and wiggles.

Thirty-six weeks into pregnancy, or 34 weeks after conception, your baby's skin is becoming smooth as more fat is added under the skin. The limbs start to look chubby.

Most babies have turned head down by this point. If your baby isn't head down, your healthcare professional may talk with you about ways to move the baby in that direction. That's usually done around week 37.

Thirty-seven weeks into your pregnancy, or 35 weeks after conception, your baby can grasp things firmly.

To get ready for birth, your baby's head might start going down into your pelvis. At this point, your baby is considered early term.

Thirty-eight weeks into pregnancy, or 36 weeks after conception, the measurement around your baby's head and around the belly are about the same.

Your baby's toenails have reached the tips of the toes. At this point, most of the lanugo is gone.

By now, your baby might weigh about 6 1/2 pounds (2,900 grams). But size varies quite a bit. Some babies may weigh nearly 9 pounds (4,000 grams) or more by this point in pregnancy.

Thirty-nine weeks into your pregnancy, or 37 weeks after conception, your baby is considered full term.

The chest is getting larger. Fat is being added all over the body to keep your baby warm after birth.

Forty weeks into pregnancy, or 38 weeks after conception, your baby might have a crown-to-rump length of around 14 inches (360 millimeters) and weigh about 7 1/2 pounds (3,400 grams). But remember that healthy babies come in lots of sizes.

Don't be worried if your due date comes and goes with no signs of labor starting. The due date is simply an estimate of when your pregnancy will be 40 weeks along. It doesn't predict exactly when your baby will arrive. Many people give birth before or after their due dates.

March 18, 2025

Original article: https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/fetal-development/art-20045997