Third Trimester: 28 Weeks to Birth

May 11

Written By ALIES

May 11, 2026

The third trimester is the final stage of pregnancy. The fetus gains weight rapidly, building body fat to stay warm and healthy after birth. Many women will see their doctor every two weeks, and then weekly as the due date approaches.

The uterus now stretches from the pubic bone to the ribs. Late in this trimester, the baby will “drop” into your pelvis, which can bring pressure and a stronger urge to urinate. Women may also notice backaches, swelling, shortness of breath, and fatigue. Rest, staying hydrated, and gentle exercise can help relieve these symptoms.

By the end of this trimester, the baby’s organs are nearly fully developed, the lungs are maturing, and they are getting ready to meet the world!

28 Weeks LMP

At this stage of pregnancy, fetuses will often stick out their tongues. It is speculated that they are trying to taste the amniotic fluid.

29 Weeks LMP

The fetus is still moving around and kicking quite a bit, although it is getting more cramped in the amniotic sac.

30 Weeks LMP

The fetus is about 17 inches long from head to toe.
The fetus can better regulate their body heat and continues to gain body fat.

31 Weeks LMP

The fetus can hear distinct sounds, and a familiar voice may trigger movement.
All major organ development is complete, although the lungs and brain are still immature.

32 Weeks LMP

The fetus weighs almost 4 pounds.
The fetus is so big now that all the space in the uterus is filled up!

33 Weeks LMP

The fetus rapidly accumulates more body fat for warmth and energy after birth.
The fetal bones are hardening, except for the cranial bones around the brain, which must remain soft to allow passage through the birth canal.

34 Weeks LMP

At 34 weeks of pregnancy, a baby is considered late preterm. Many babies born at this stage do very well, especially if they have no other health complications.
The fetus is building up brown fat, the type of fat that helps them generate heat after birth. If born at this stage, they may initially have difficulty regulating their body temperature, which is why they might spend time in a warm incubator.

35 Weeks LMP

At 35 weeks, most babies can breathe on their own if they are born.

36 Weeks LMP

At the end of this week, the fetus is considered full term. Most women go into labor between 37 and 42 weeks.

Fetal and embryological development occur rapidly. If you would like a more in-depth understanding of what happens during pregnancy and the developmental milestones, you can speak with your doctor or contact us.