Third Trimester

What happens in the third trimester

The third trimester covers week 28 through birth, usually around week 40. This is the home stretch: the baby gains most of its birth weight here, appointments get more frequent, and the practical work of preparing for labor and a hospital stay (or home birth, if that is the plan) moves to the front burner.

A rough week-by-week shape

Weeks 28 to 32 often bring more noticeable Braxton Hicks contractions and shortness of breath as the uterus takes up more room. Weeks 32 to 36 are when many providers start checking the baby's position, since head-down is the preferred position for a vaginal delivery. From 36 weeks on, appointments usually become weekly, and the baby is considered full-term at 39 weeks. For a full breakdown of what to expect week by week, see Everything to Expect in the Third Trimester of Pregnancy.

Common symptoms

Back pain, pelvic pressure, swelling in the feet and ankles, heartburn, trouble sleeping, and frequent urination (as the baby presses on the bladder) are all common. Braxton Hicks contractions, sometimes called practice contractions, tend to show up more in this trimester. Knowing the difference between these and real labor matters for deciding when to call your provider or head to the hospital; see Braxton Hicks vs. Real Contractions for a clear comparison.

Appointments and tests

Visits typically move to every two weeks from 28 to 36 weeks, then weekly until delivery. Your provider will screen for Group B strep (a common bacteria that is usually harmless in adults but treated with antibiotics during labor if present) around 36 to 37 weeks. Blood pressure, weight, and urine are checked at every visit to watch for preeclampsia, and your provider will discuss the baby's position and, closer to your due date, options if the baby has not turned head-down.

Practical checklist for this trimester

When to call your provider

Call right away for regular contractions before 37 weeks, your water breaking, heavy bleeding, a noticeable drop in fetal movement, severe headaches or vision changes, or sudden swelling in the face and hands. These can signal preterm labor or preeclampsia, both of which need prompt evaluation.

How these guides fit together

Use the week-by-week guide to know what is coming next, the Braxton Hicks comparison to sort out real contractions from the practice kind, and the birth plan guide to turn your preferences into something concrete you can bring to your appointments and, eventually, the delivery room; see Birth Plan Guide.

Frequently asked questions

How often are appointments in the third trimester?

Typically every two weeks from 28 to 36 weeks, then weekly from 36 weeks until delivery. Your provider may see you more often if there are any concerns to monitor.

How do I tell Braxton Hicks from real labor contractions?

Braxton Hicks contractions are usually irregular, do not get closer together over time, and often ease up with rest or a position change. Real labor contractions tend to fall into a regular pattern, get stronger and closer together, and do not stop with rest.

When should I pack my hospital bag?

Most providers suggest having it ready by around 36 weeks, since labor can start earlier than the due date. Packing early means one less thing to think about if labor starts unexpectedly.

For more on what to expect near your due date, see ACOG's prenatal care guidance.