27 Weeks Pregnant: Symptoms, Baby Development and What to Expect

At 27 weeks pregnant you are about 6 months along, in the last week of the second trimester by the ACOG definition, with about 13 weeks to go until your estimated due date.

Week 27 is a hinge week. Your baby is filling out, your bump is hard to miss, and two time-sensitive items land on your calendar: a vaccine window opens and a blood sugar test window closes.

This guide covers development, size, symptoms, appointments, sleep and the signs that mean you should call. Every clinical detail was read in October 2026 on the primary sources named in the text.

27 Weeks Pregnant at a Glance

How the weeks are counted. Pregnancy is counted from the first day of your last normal period (LMP), not from conception, and lasts about 40 weeks on that count (Office on Women’s Health). That is why Mayo Clinic labels week 27 as 25 weeks after conception. If an early ultrasound changed your due date, use the adjusted dates.

Is 27 weeks the second or third trimester? It depends on whose calendar you use:

Your care is the same on every calendar. Our third trimester guide picks up from here.

Your Baby’s Development at 27 Weeks

These are the changes the sources date to week 27 and the weeks just before it.

Nemours KidsHealth adds that you might feel your baby hiccupping.

How Big Is Your Baby at 27 Weeks?

Nemours KidsHealth gives a week 27 figure: about 2 1/4 pounds (1 kilogram) and about 13 3/4 inches (35 centimeters) long. Mayo Clinic has no week 27 measurement, so its nearest figure is shown with the Office on Women’s Health numbers on either side.

Mayo’s length is shorter because it measures crown to rump, which leaves out the legs. The other two pages do not say how they measure. We have not converted any numbers.

For a comparison, UPMC says a baby is about the size of a cauliflower by 27 weeks. These are averages, and healthy babies vary.

27 Weeks Pregnant Symptoms

Every pregnancy is different (Office on Women’s Health), so you may have several of these or very few.

• Back, hip and body aches: the Office on Women’s Health lists aches in the back, abdomen, groin and thighs. UPMC suggests walking, swimming and other low-impact exercise.
• Heartburn: the growing uterus presses on the stomach and pushes acid up (UPMC). MedlinePlus advises against a big meal within a few hours of bed.
• Leg cramps: if one wakes you, MedlinePlus suggests pressing your feet hard against the wall.
• Swelling: of the ankles, fingers and face (Office on Women’s Health). Sudden or extreme swelling, or gaining a lot of weight really quickly, could be a sign of preeclampsia: call your doctor right away.
• Shortness of breath: MedlinePlus lists it among the reasons sleep gets harder. Sudden trouble breathing is a warning sign (see below).
• Constipation and bloating: your uterus pushes on your intestines. Nemours KidsHealth suggests plenty of water and fiber from fruits, vegetables, whole grains and beans.
• Stretch marks and itchy skin: UPMC describes both as skin stretches. Call if itching comes with nausea, vomiting, jaundice or fatigue (Office on Women’s Health).
• Tightenings: contractions can be a sign of real or false labor (Office on Women’s Health). Regular or frequent tightening this early needs a call. See what contractions feel like.

Your Body and Belly at 27 Weeks

Your bump is obvious now, and no two look alike. UPMC says providers start measuring fundal height around week 24, using a tape measure from your pubic bone to the top of your uterus. For a wider view, see pregnant belly by month.

• Skin: the Office on Women’s Health describes stretch marks, a line running from the belly button to the pubic hairline, and darker patches on the face.
• Appetite: UPMC says you need about 340 more calories a day in the second trimester.
• Movement: Nemours KidsHealth says you are likely feeling your baby move a lot more than before.

Kick counts. Cleveland Clinic says kick counting becomes more important in the third trimester and that 10 movements in one or two hours is typical. It reports that ACOG recommends checking for 10 within two hours. Ask your provider when to start. At any stage, the CDC lists a baby who is moving less than before as an urgent warning sign.

Prenatal Care, Tests and Appointments Around Week 27

If you have not had your glucose test, ask this week: the window is closing.

Vaccine guidance changes. The CDC page we read was last updated in June 2024, so confirm flu, COVID-19 and other vaccines with your own provider.

A 27 week ultrasound? None of these sources schedules a routine scan this week. UPMC places the anatomy scan at about 20 weeks, and Nemours KidsHealth mentions an ultrasound around now to see the baby’s position.

What to Do This Week: A Simple Checklist

• Ask about the Tdap vaccine. The CDC window opens this week.
• Confirm glucose screening is done or booked before the end of week 28.
• Rh negative? Ask when your Rh immune globulin shot is planned.
• Sign up for a childbirth class. It is on UPMC’s second trimester to-do list.
• Start a birth plan and a short list of pediatricians.
• Save your provider’s after-hours number and learn the warning signs below.
• Begin the bigger projects: nesting and your baby registry checklist.

Sleep at 27 Weeks Pregnant

MedlinePlus says sleep often gets harder later in pregnancy: a good position is tough to find, bathroom trips multiply, and heartburn, aches, shortness of breath and a baby who is more active at night all play a part.

Sleep position. MedlinePlus does not tie its advice to a specific week. It says to try sleeping on your side, that lying on your side with your knees bent will likely be most comfortable, that many providers suggest the left side, that switching to the right for a while is OK, and that it is best not to sleep flat on your back.

• Use pillows: under your belly or between your legs (MedlinePlus). See how to use a pregnancy pillow.
• Watch the evening: limit soda, coffee and tea, and avoid a lot of fluids or a big meal within a few hours of bed.
• Keep a rhythm: go to bed and wake up at the same time each day, and take short naps to make up for lost sleep.
• Skip sleep aids: MedlinePlus says not to take any, including over-the-counter medicines and herbal products. Read can you take melatonin while pregnant and ask your provider first.

For Partners: How to Help at 27 Weeks

• Keep her company at the glucose test: it involves a one hour wait.
• Talk to the bump. Nemours KidsHealth says the baby may start to recognize your voice too.
• Take over jobs that strain an aching back, such as laundry baskets and low cupboards.
• Learn the warning signs below so you can make the call if she is unsure.

Looking Ahead: What Comes Next

• Week 28: the third trimester begins by the ACOG definition (the Office on Women’s Health starts it at week 29). Our third trimester guide covers it in depth.
• If you are Rh negative: Cleveland Clinic says Rh immune globulin is typically given around 28 weeks, and again within 72 hours of delivery if the baby is Rh positive.
• More visits: Nemours KidsHealth says that as pregnancy goes on you will likely see your doctor every few weeks.
• Weeks 32 to 36: the CDC’s RSV vaccine window, during September to January.

Looking back? See 22 weeks pregnant.

Related Betteroo Guides

• 22 weeks pregnant
• Third trimester guide
• Pregnant belly by month
• How to use a pregnancy pillow
• When does nesting start?
• What do contractions feel like?

When to Call Your Provider

Signs of preterm labor. March of Dimes defines preterm labor as labor before 37 weeks and says to call your provider right away if you have even one of these:

• Regular or frequent contractions that make your belly tighten like a fist. They may or may not be painful.
• A change in your vaginal discharge (watery, mucus or bloody), or more discharge than usual.
• Pressure in your pelvis or lower belly, like your baby is pushing down.
• A constant low, dull backache.
• Belly cramps, with or without diarrhea.
• Your water breaks. See signs of leaking amniotic fluid.

Urgent maternal warning signs. The CDC’s Hear Her campaign says to seek medical care immediately for any of these, and to say that you are pregnant:

• A headache that won’t go away or gets worse over time, or changes in your vision.
• Extreme swelling of your hands or face.
• Vaginal bleeding or fluid leaking.
• Your baby’s movement stopping or slowing.
• Severe belly pain that doesn’t go away.
• Trouble breathing, chest pain or a fast-beating heart.
• Dizziness or fainting, overwhelming tiredness, or a fever of 100.4 F or higher.
• Severe nausea and throwing up.
• Severe swelling, redness or pain in a leg or arm.
• Thoughts about harming yourself or your baby.

If you cannot reach your provider quickly, go to labor and delivery or the nearest emergency room, or call 911. This article is general education, not medical advice.

Frequently Asked Questions