Fetal development: The 3rd trimester

Fetal development continues during the third trimester. Your baby will open his or her eyes, gain more weight, and prepare for delivery.

By Mayo Clinic Staff

The end of your pregnancy is near! By now, you're eager to meet your baby face to face. Your uterus, however, is still a busy place. Here's a weekly calendar of events for fetal development during the third trimester. Keep in mind that measurements are approximate.

Week 28: Baby's eyes partially open

Twenty-eight weeks into your pregnancy, or 26 weeks after conception, your baby's eyelids can partially open and eyelashes have formed. The central nervous system can direct rhythmic breathing movements and control body temperature.

By now your baby might be nearly 10 inches (250 millimeters) long from crown to rump and weigh nearly 2 1/4 pounds (1,000 grams).

Week 29: Baby kicks and stretches

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

Week 30: Baby's hair grows

Thirty weeks into your 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 are forming in your baby's 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).

Week 31: Baby's rapid weight gain begins

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

Week 32: Baby practices breathing

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 (lanugo) starts to fall off this week.

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

Week 33: Baby detects light

Thirty-three weeks into your pregnancy, or 31 weeks after conception, your baby's pupils can change size in response to a stimulus caused by light. His or her bones are hardening. However, the skull remains soft and flexible.

July 06, 2017 See more In-depth