Third Trimester: What’s Happening in Your Body

By OBOS Pregnancy & Birth Contributors | April 7, 2014

In the third trimester, your baby is growing a tremendous amount. Your belly—and for some
of us, other body parts, too—will be getting very big.

I had a big tummy and a big butt to match. Even though I was huge, it was okay with me. My big belly made everything make sense. I really was pregnant! I really was going to be a mother! I really did have every right to be shopping for baby clothes and to be treated with special care!

Your growing belly may elicit comments from well-meaning others who have opinions about your size relative to other pregnant women.

Sometimes I’d hear, “Oh, you’re so small” and “Are you having twins?” in the same day. The comments were so mixed I learned to just laugh and brush them aside. This might not have been the case if I’d constantly heard the same thing—I might have started to believe it.

Many people like to touch big pregnant bellies, and sometimes they do so without asking permission. Most of the time, people’s intentions are loving and they are reaching out toward your belly because seeing it has brought them joy. However, it is your body and you have the right to decide who can touch it. Women have very different feelings about this.

I usually didn’t mind it much, except when they were complete strangers who’d strike up a conversation about my pending due date and feel like they needed to touch it, like you’d pet a dog if you were talking to its owner.

Your baby’s movements become stronger as well. You may feel full-body movements as opposed to the flutters of the second trimester. You may also be able to distinguish body parts. Your partner or others will be able to feel the baby move if they can catch the right moment.

We were in England for my husband’s grandmother’s funeral, and late at night he felt [the baby] move for the first time. What a welcome moment of life in the midst of grief.

As she grew bigger and more active, I described the feeling as an alien invasion. I would often feel as though she could potentially kick her way out!

You may also notice the baby responding to sounds in the environment.

The most amusing movements were when listening to various types of music in later pregnancy and wondering if the increased movements were because the baby liked or hated what we were listening to.

The increased size and weight of the baby can bring about other changes as well. You may feel the baby’s head on your pubic bone or bladder (leading to increased frequency of urination). As your ligaments loosen in preparation for birth, you may also experience backaches and pain with walking.

It became uncomfortable to sit for long periods. It was also hard to find a comfortable position to sleep. I stopped being able to hike long distances. One little muscle in my butt was controlling my life.

Your fundus, which is the top of the uterus, will be high up in your abdomen, and this can lead to heartburn, inability to eat large meals, and shortness of breath. The pressure from the baby’s weight may create hemorrhoids or other varicosities (for example, dark veins in your legs).

Toward the end of pregnancy, you will begin to produce colostrum, a protein- rich fluid your breasts make before mature breast milk comes in. Your breasts begin to fill up with colostrum and may leak some of this fluid. Some women notice swelling in the ankles, as well as increased body heat and perspiration. You may also experience lighter sleep with lots of interruptions (often to use the bathroom).

Many women remain active until the end of pregnancy. You may find that even if you continue to participate in your regular activities, diminishing energy causes you to cut back and slow down a bit.

During the third trimester, many women experience increased Braxton-Hicks contractions. As birth draws near, the contractions may begin to change, becoming more frequent and even feeling a little crampy. Sometimes several contractions will come in a short period of time, and you may think that you are in labor.

Then the contractions stop and you go about your day (or night). These contractions begin to soften your cervix, helping to get it ready for labor.

At approximately 36 weeks or beyond, some babies will move down into the pelvis. This is known as engagement, or “lightening.” If your baby moves down in this way, you may feel pressure on your bottom, as if a grapefruit is sitting in your pelvis. You may be able to eat a bit more and breathe more easily.