Third Trimester of Pregnancy

Key Highlights for the Third Trimester

The third trimester is exciting and beautiful and weird and scary; you’ll feel all the emotions as you approach the day you get to meet baby. In the meantime, expect to be uncomfortable. Your bump will continue to expand, you’ll have aches and pains and you’ll experience all sorts of new or returning symptoms (hello again heartburn, spider veins and frequent urination). Meanwhile, baby’s organs and systems will continue to mature and develop as the weeks go by. Prenatal visits will become more frequent, and you’ll want to be diligent about attending all appointments. Your doctor or midwife will continue to monitor your health and baby’s well-being, and you’ll get some important tests and revealing updates. Time is simultaneously flying and crawling—hang in there, you’re at the home stretch!

When Does the Third Trimester Start and End?

The third trimester begins on day one of week 28. While pregnancy is generally considered a 40-week journey, lots of babies arrive earlier, and some stay put past their due date. Of course, it’s also important to remember that due dates are estimates, so it’s totally normal if baby doesn’t arrive on the day you’ve had circled on your calendar for months. That said, most doctors won’t let you go beyond 42 weeks, and may suggest medically inducing labor before that point.

Third Trimester Symptoms

The finish line is nearing—baby will be in your arms before you know it! But first: a few fun surprises. Yes, the third trimester is chock full of unexpected new symptoms (oh joy!). Rest assured, though, that these slightly unpleasant developments are getting you closer to delivery day.

Braxton Hicks contractions

Before you experience real labor contractions, you may get some practice in the form of Braxton Hicks. These irregular contractions can start some time in the second or third trimester, and help to tone the muscles of your uterus and prepare your cervix for birth.

Lightening

If a friend comments that you’re suddenly carrying lower, you may have experienced lightening or “dropping” in late pregnancy. This is when baby drops into the lower pelvis in preparation for delivery. Not only will your bump look lower, you may feel lighter too. You might even find it easier to breathe and eat now that baby isn’t all up in your ribs! That said, you’ll probably have to pee more often, as baby presses down on your bladder.

Lightning crotch

Toward the end of pregnancy, you might experience random jolts or zaps of pain in your crotch region. Lightning crotch is normal, common and completely harmless, but it may catch you off guard. The good news: It doesn’t last long. It’s a momentary discomfort, and changing positions should help.

Baby Development in the Third Trimester

Baby is getting bigger and their body begins to fill out a bit with a layer of brown fat. Meanwhile, their organs continue to mature, especially the lungs which helps them with their practice breathing. Baby’s reflexes are developing, and their five senses become largely functional (they love the sound of your voice!). Their bones continue to harden and their cartilage gets firmer. Around 37 weeks, meconium (aka baby’s first poop) begins to form. Suffice it to say, a lot is happening behind the scenes to get baby ready for their big debut.

What to Avoid During the Third Trimester

Generally speaking, you’ll want to avoid the same things in the third trimester that you’ve been steering clear of all along. That means no alcohol, smoking or illicit drug use. You’ll want to continue staying away from unpasteurized cheeses and juices, deli meats, raw fish and a few other risky foods. Avoid overly strenuous physical work and exercise, and any activity that raises your core body temperature (no dips in the hot tub). You also continue to get a free pass from changing the cat litter for a while. Finally, talk to your doctor or midwife before traveling in the third trimester. If things are progressing as expected, your provider may give you the green light to hop on a flight up until 34 to 36 weeks; just keep in mind that some airlines have their own policy regarding third-trimester air travel.

When to Reach Out to Your Doctor in the Third Trimester

Undoubtedly, the third trimester will be uncomfortable. Aches and pains are par for the course, but there are a few red flags to watch for. If abdominal pain is severe and unrelenting, if you have regular contractions before 37 weeks or experience significant vaginal bleeding or leaking of fluid, contact your doctor right away; these may indicate preterm labor. Also reach out if you are experiencing blurred vision, headaches and swelling, as these symptoms could indicate preeclampsia, a complication typically marked by high blood pressure. Finally, seek medical attention if you notice a major reduction in baby’s movement (less than 10 kicks in two hours) when doing kick counts.

What's Coming Next?

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Third Trimester Videos

Whether you’re wondering what happens during your third trimester or looking for advice on preparing for labor, we’re here to help. Click play on the videos below to find out more.

Third Trimester Tools

Starting to feel contractions? Exciting! But it doesn’t necessarily mean it’s time to head to the hospital just yet. To help you gauge how far apart your contractions are, use our handy Contraction Counter tool below. Still searching for the perfect baby name? Try our baby name finder.

Planner+Baby RegistryContraction CounterBaby Name Finder

Community Forums

Feeling nervous? Excited? A little bit of both? Join our discussion forums, like our third trimester forums and birth month clubs, to chat with real-life parents like you. Ask questions, offer advice and create lifelong connections.