When Do Contractions Start in the Third Trimester?

Are your contractions Braxton Hicks, pre-labor, or active labor? Learn how to tell the difference when contractions start.

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Photo: Juan Aunion/Shutterstock

As you approach your baby's due date, you may be wondering, when do contractions start? Optimally, true labor contractions won't begin in earnest until close to your due date, but you might feel some contractions on and off during the third trimester. These non-labor contractions are called Braxton Hicks contractions.

What Are Braxton Hicks Contractions?

Braxton Hicks contractions are often considered "practice" contractions. They differ from real labor contractions because they don't cause your cervix to open (dilate) or thin out (efface).

Read on to learn the difference between Braxton Hicks and labor contractions and what causes Braxton Hicks. Plus, learn the signs of labor and when contractions may indicate a pregnancy complication, like early labor.

Braxton Hicks vs. Labor Contractions

According to the American College of Obstetricians and Gynecologists (ACOG), Braxton Hicks are common in the third trimester. Even though they are not true labor contractions, they can still be uncomfortable, often leading people to believe they are in the early stages of labor when they're not.

Unlike labor contractions, Braxton Hicks contractions have the following characteristics:

  • They tend to fizzle out when you rest, walk, change positions, or drink water.
  • They don't follow a pattern or get stronger or closer together.
  • They are felt almost entirely in the abdomen, while labor contractions often move from the back to the front.

If you've given birth before, you may notice more Braxton Hicks contractions that begin earlier. "You may get an occasional, uncomfortable tightening in the stomach—that's your uterus getting its act together and exercising for the grand finale," says Paul du Treil, M.D., director of maternal and child health at Touro Infirmary in New Orleans.

Braxton Hicks contractions are usually sporadic, slightly uncomfortable, and last anywhere from 30 seconds to two minutes. There's no need to call your health care provider for occasional Braxton Hicks contractions; most people begin to notice them sometime after 20 weeks of pregnancy.

What Causes Braxton Hicks Contractions?

Braxton Hicks are believed to be your body's way of preparing for labor. They are essentially warm-up exercises for your uterus! There are certain things that can make Braxton Hicks more likely.


You may not want to slow down during the third trimester, but overtaxing your body could cause your uterus to start these practice contractions. "If you're doing too much, you could cause Braxton Hicks contractions," Dr. Putterman says. The good news is that Braxton Hicks contractions often go away once you put your feet up and chill.


Dehydration can also kick-start those Braxton Hicks contractions, so be sure to drink plenty of water. "If a patient calls about their contractions, one of the first things we tell them is to go drink a big glass of water," Dr. Putterman says. "If they don't feel better, they probably need to come in and get checked."

As it happens, a too-full bladder can also cause Braxton Hicks contractions, so make sure that you also urinate often.

Having sex

Having sex has also been linked to jump-starting Braxton Hicks contractions. It's probably because orgasms cause the uterus to contract. In addition, with penis-in-vagina sex, the prostaglandins in semen can cause uterine contractions.

These contractions should subside soon after they begin. But, as always, call a health care provider if they're becoming longer or more intense or if they fall into a predictable pattern.

What Are the Signs of Labor Contractions?

Optimally, true labor contractions won't start until you are at full term, which begins at 39 weeks. According to ACOG, most people go into labor between 38 and 41 weeks of pregnancy. So contractions in this window could indicate the real thing.

According to ACOG, signs of true labor contractions include:

  • Pain that may be felt in your back and pelvis
  • Contractions that may feel like menstrual cramps
  • Contractions that have a regular pattern and are getting longer, stronger, and closer together over time
  • Contractions that continue regardless of your activity

Unlike Braxton Hicks contractions, true labor contractions are productive. That means these contractions work hard to soften and open the cervix and move the fetus toward the birth canal.

Although labor contractions may start out irregularly, they'll soon start developing a regular rhythm. "If it's real labor, the contractions are going to gradually get closer together and longer and stronger," Dr. Putterman says.

In most cases, health care providers recommend that you head to the hospital or birthing center once your contractions are about a minute long and are four to five minutes apart. But your health care provider may suggest a different threshold for you, depending on your risk factors, your proximity to the hospital, and other personal considerations.

Contractions Due to Prodromal Labor

Prodromal labor—also called "false labor" or "pre-labor"—is different from Braxton Hicks contractions in that it only occurs when you're close to going into labor. As a result, it is often mistaken as real labor and can be very frustrating.

Signs of prodromal labor contractions are similar to Braxton Hicks in that they involve a tightening sensation, primarily in your abdomen, and they do not grow in intensity or frequency.

However, unlike Braxton Hicks, they may last longer (up to a minute) and be more frequent (around five minutes apart). In that way, they have more of a pattern and mimic labor contractions. Another feature that distinguishes prodromal labor from Braxton Hicks is that activity change usually doesn't stop prodromal labor.

Contractions Due to Pregnancy Complications

Contractions may also start early if you go into preterm labor, which is defined as labor that begins before you've finished your 36th week of pregnancy. Some things place people at higher risk of going into preterm labor. According to the Insitute of Child Health and Human Development, these include:

  • Multiple pregnancy (being pregnant with two or more fetuses)
  • History of preterm birth
  • Short cervix
  • Infections
  • High blood pressure
  • Vaginal bleeding
  • Fetal congenital anomalies
  • Placenta previa
  • Being at risk for uterine rupture
  • Diabetes
  • Blood clotting problems
  • Being over- or underweight
  • Being younger than 18 or over 35
  • Smoking or using alcohol or drugs
  • Stress

Premature labor contractions are characterized by a pattern of twinging or tightening of the uterine wall (not occasional pain) that doesn't go away. "If you're having a lot of contractions for several hours in a row, then you need to come in and be evaluated," says Bart Putterman, M.D., an OB-GYN at Texas Children's Pavilion for Women in Houston.

Preterm labor might lead to premature birth, which is linked to fetal breathing problems, low birth weight, vision problems, and other issues. So it's essential to get any early labor symptoms—including painful contractions and vaginal bleeding—checked out right away.

Continuous contractions are also a sign of trouble; even in the thick of labor, your body will give you a short break between contractions. So if your contractions don't take a breather, it could indicate a dangerous complication, such as uterine rupture.

In addition, ACOG recommends going to the hospital immediately when your water breaks (whether or not you are having contractions), you are bleeding heavily from the vagina, you have severe pain and constant contractions, or you notice less fetal movement.

Can You Start Contractions on Your Own?

If you're antsy to deliver your baby, you may wonder how to start contractions at home. However, waiting things out as long as possible is usually best. Vital fetal development happens even in the last weeks of pregnancy, and attempting to induce labor yourself can have negative consequences.

That said, if your body is ready for labor, certain things can create favorable circumstances for going into labor. These include:

  • Certain movements (such as pelvic tilts and sitting on a birthing ball)
  • Having sex
  • Walking

If you're ready to get the labor party started, talk to a health care provider about your options for jumpstarting labor at home.

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