What to expect during the third trimester of pregnancy

When you’re pregnant, you’ll likely have a lot of questions about what is happening to your body during each trimester and what is happening with your baby’s development week by week. Jade Elliott spoke with Leah Moses, a certified nurse midwife with Intermountain Healthcare, about some of the most common questions she has women ask when they come in during their third trimester for prenatal visits and to explain why those visits are so important to help you and your baby stay healthy.

Your third trimester begins at about 25 weeks of pregnancy. The third trimester is a time of more frequent prenatal visits, usually every two weeks from 28-36 weeks and every week from 36 weeks until delivery.

Screenings during the third trimester

If you haven’t already had a glucose tolerance test, your doctor or midwife will recommend one between 24-28 weeks.

Group B Strep Test

Nationally, it’s recommended that all pregnant women be tested late in pregnancy (usually starting at about 36 weeks to detect Group B Strep bacteria.

Group B streptococcus [strep-tuh-KOK-uh s] or group B strep is a common bacteria that can live in the human genital and gastrointestinal tract. It’s not the same bacteria that causes strep throat, and in adults it usually doesn’t cause illness. When a pregnant mom has Group B Strep, it can be dangerous because the unborn baby can be exposed to this bacterial environment once mom’s water breaks and during childbirth. Infection can cause serious, even life-threatening, problems in a newborn, such as lung infections, blood infections, and meningitis (inflammation of the tissues around the brain and spinal cord).

Group B Strep is common. Studies show about 20 percent (1 out of 5) pregnant women carry the Group B Strep bacteria but have no symptoms. Based on data from the Utah Department of Health from Jan 2015 – July 2019, the incidence of newborn infection caused by GBS is higher in Utah compared to the national incidence.

If you do test positive for Group B Strep, simple precautions need to be taken before your baby is born.

Why is it important to manage high blood pressure during pregnancy?

Your blood pressure is checked at every prenatal visit. This is especially important to detect preeclampsia or other complications that may manifest in the third trimester.

Complications of high blood pressure can be very serious and include:

  • Preeclampsia, when high blood pressure can lead to organ damage in the mother and ultimately cause problems with the baby
  • Eclampsia, when the mother can have seizures
  • A stroke due to very high blood pressure.
  • Decreased blood flow to the placenta can lead to baby receiving less oxygen and fewer nutrients, causing low birth weight
  •  Sometimes a recommendation is made for a preterm delivery

Measuring baby’s growth

At each visit, a fundal height measurement is taken to make sure baby’s growth is correct. This measures the length from the pubic bone to the top of belly. Generally, you’ll measure the same number of centimeters as weeks you are pregnant.

Increasing fatigue and discomfort

Fatigue very common during the third trimester. Many women have increased ligament and muscle, pain or back pain as baby grows larger. Remedies include a warm shower, warm pack, or in some cases pelvic physical therapy.

Because of the extra fluid in your body, your hands and feet may swell, especially toward the end of the day. Some women find they need to go up a shoe size to allow for this change.

Sleep challenges

As you become more uncomfortable or have increasing heartburn, getting good sleep at night can be a challenge. Think of it as your body getting you ready for when your baby will wake you up in the night. It’s important to have a good attitude. For best blood flow, lay on your left side rather than flat on your back. But don’t worry about it too much. A pillow between the legs or a body pillow can help you find a comfortable position.

Breast changes

By 29 weeks, your breasts have begun to produce colostrum. Also called pre-milk, colostrum will be the first meal for a breastfed infant. Colostrum is usually thick and yellowish and may leak from your breasts. This is a normal sign that your body is preparing for your baby’s arrival.

Skin changes

As your skin stretches it may feel itchy and stretch marks may develop. Using lotion can help dry, itchy skin.

Baby’s development during the third trimester

As your baby grows larger, you may feel your baby’s movement more strongly, or some women feel movement is more subtle, since there’s not a lot of room for baby to move around. Your internal organs are feeling the squeeze of your rapidly growing baby.

Your baby begins to gain more fat during the third trimester to reach a healthy birth weight. Baby can gain a pound per week in the final weeks. The wrinkles on the skin smooth out and the cheeks plump slightly. The bones begin to harden. The hair on your baby’s head may take on color and texture. Your baby begins to shed the downy lanugo hair that has covered his or her body for the first weeks of life.

Your baby’s lungs become fully developed at 37 weeks. Your baby’s hearing develops, and he or she can differentiate between mom and dad’s voices. Eyelashes develop.

Sign up for a prenatal class

If you haven’t already, sign up for a prenatal class to help you know what to expect during labor and delivery and how to prepare for it and how to create a birth plan. Intermountain has online options available. Keep in mind that everything in labor and childbirth doesn’t always go as planned, so be flexible in your plan. Elective inductions are not recommended. It’s also a good idea to learn all you can ahead about how to care for your newborn baby and take a breastfeeding class.

Identify your labor coach and or support people

Talk to your partner, doula, family or friends and determine who you want to be there during labor and delivery. Be sure to check the visitor policy with your local hospital.

This is also a good time to talk about what support you’ll have at home after the birth while you’re recovering.

Now that you’re really showing in the third trimester, many women report that everyone wants to tell you their birth story. It’s ok to set boundaries. Some stories are inspiring, and others might create fear. You can stop and tell them you want your own labor experience and will I’d hear about their story later.

Nesting Instinct

Cleaning. decorating, setting up the baby’s room. Organizing things at home. According to researchers, pregnant women’s “nesting instinct” is quite real, very common, and probably triggered by surging hormones. Whatever the cause, your preoccupation with domestic affairs right now can be handy. It’s a good nudge to help you prepare your home for a new resident.

Pack Your Hospital Bag

Pack your bag for the hospital ahead of time. You never know when you might go into labor or if labor might progress very quickly.

Labor signs

In your final prenatal visits, your doctor or midwife will check your cervix. With gloved fingers, your healthcare provider will gauge whether and how much the cervix has thinned and shortened (effaced) and opened (dilated). Cervical changes are clues to your body’s readiness for labor. You may be dilated to 2-3 cm for a couple of weeks before delivery.

At 36 weeks, your provider will check to see if your baby is in the head down position and getting ready for delivery. Your provider can Can do help give you exercises or manually turn the baby if needed.

Braxton Hicks – or practice labor contractions

Dehydration can lead to contractions that are not labor contractions. Be sure to stay hydrated

Braxton Hicks contractions are a tightening of the uterine muscles. They can last 30 seconds to a few minutes. They can feel strange, but they’re not usually painful. They go away. It’s thought that these contractions are like uterine warm-ups, helping to tone and ready your body for the intense contractions of true labor.

True Labor

Labor contractions feel like strong menstrual cramps or a lower backache that comes and goes.

You’ll know you’re in true labor if your contractions:

  • Are regular and follow a predictable pattern (such as every 9 minutes)
  • Gradually get closer together
  • Last progressively longer

When to call your doctor or midwife

Call your provider if your water breaks. Your vaginal fluid becomes thinner and may leak a bit. You will know if your water breaks, it will drip down your legs. You should also call your provider if you have bright red bleeding. Some blood tinged mucous is normal.

Call your provider when your contractions are regular and are four to five minutes apart and continue for an hour.

As you finish your third trimester, take care of yourself and plan for how you can take a break and practice self-care after your baby is born. Adjusting to the demands of a new baby and your growing family takes time. It’s kind of like the fourth trimester. Be patient with yourself and enjoy the precious time you have with your baby.

For more information about pregnancy or to find a women’s health provider, visit intermountainhealthcare.org

Intermountain offers online childbirth preparation and breastfeeding classes or you can call your local hospital for more information.

Other pregnancy resources:



The Baby Your Baby program provides many resources for all pregnant women and new moms in Utah. There is also expert advice from the Utah Department of Health and Intermountain Healthcare that air each week on KUTV 2News.