5 Things That Cause Contractions Before Labor

Pregnant Couple Laughing in Bed
Blend Images/Getty Images
Table of Contents
View All
Table of Contents

Contractions are the one thing that most people focus on when it comes to deciding what is labor and what isn’t labor. But, simply having contractions is not the same thing as being in labor. You might find yourself wondering: What are the causes of contractions? Did you know that there are many things that can cause contractions?

Contractions occur in pregnancy when you have a certain level of oxytocin flowing in your blood. This can be very normal, like labor, when your body and your baby's brain release oxytocin to stimulate contractions for labor. Or it can happen if you are dehydrated, meaning a little bit of oxytocin your body would have ignored earlier is in greater concentration, and now you're having contractions.

Here are some times when contractions happen and what you need to do about them.

Vaginal Exams 

At the end of pregnancy, your practitioner might want to do a vaginal exam to do a Group B strep test or to assess your cervix. Sometimes having a vaginal exam tends to stir up some annoying, irregular contractions. This is particularly true if the membranes were also swept or stripped.

These contractions are often uncomfortable and can be painful. They tend to shift around in length and timing. The good news is that comfort measures you’ve been practicing for labor will often help out.


Sex at the end of your pregnancy can cause contractions. These contractions can be quite intense and painful. Often they subside as quickly as they arrived. Though sometimes they peter out into irregular contractions for a while before completely disappearing.

This can take up to an hour and you may also have a feeling of fullness in your abdomen after an orgasm, which is also completely normal.

Speaking of which, orgasms alone can cause contractions, even if you don't have intercourse. This can happen if you're masturbating alone or with a partner. If you have been told to avoid sex because of a history or risk of preterm labor, you will also want to ask if that means you need to discontinue orgasms without intercourse as well. 


The bigger the belly and the harder the exercise, the more likely the contractions are to be caused by the activity. Quit working out and see what your uterus does. If you are experiencing regular, painful contractions, have vaginal bleeding, experience dizziness, have a headache, experience chest pain, or notice calf pain, stop exercising immediately, and contact your doctor right away.

In most cases though, exercise is considered safe in pregnancy and is encouraged. In fact, in healthy females exercise is beneficial for both the mother and the baby.


This is a big deal. You should try to avoid dehydration because it can also be a cause of preterm labor. Stay well hydrated. Dehydration is much more common in hotter or summer months, but it is possible all year long. Be cognizant of the fact that you can quickly become dehydrated. Rehydration is the first line of defense for preterm labor, so be sure to drink water.

If you think your contractions are coming because you didn’t drink enough, drink water, sit down and call your practitioner for directions, particularly if you are not yet 37 weeks pregnant.

Nipple Stimulation

Whether this comes from sexual activity, a breast pump, or a baby — nipple stimulation can cause contractions. There are even some protocols to use nipple stimulation as a form of induction of labor. If nipple stimulation gives you contractions that last more than a few minutes, you will want to stop and check-in with your practitioner.

What to Do If You Have Contractions

If you are having more than five contractions in an hour and you are not yet 37 weeks, you will want to talk to your doctor or midwife immediately. This may be preterm labor and you will need to be seen, perhaps even in the emergency room. If you are having contractions at that rate and you are past 37 weeks of gestation, you may be in labor.

Real labor has contractions that get strong, longer and closer together. If your contractions are not progressing in this manner, you are probably not in labor.

If your contractions change patterns and do become strong, longer and closer together, reassess, maybe you are in labor! If you aren’t sure, call your doctor or midwife. They will be happy to help you decide.

6 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Childbirth Connection. The role of hormones during childbirth.

  2. U.S. National Library of Medicine. Group B streptococcus and pregnancy.

  3. Kafaei Atrian M, Sadat Z, Rasolzadeh Bidgoly M, Abbaszadeh F, Asghari Jafarabadi M. The association of sexual intercourse during pregnancy with labor onset. Iran Red Crescent Med J. 2015;17(1):e16465. doi:10.5812/ircmj.16465

  4. U.S. National Library of Medicine. Pregnancy and exercise.

  5. Takahata K, Horiuchi S, Tadokoro Y, Shuo T, Sawano E, Shinohara K. Effects of breast stimulation for spontaneous onset of labor on salivary oxytocin levels in low-risk pregnant women: a feasibility study. PLoS ONE. 2018;13(2):e0192757. doi:10.1371/journal.pone.0192757

  6. National Institute of Child Health and Human Development. What are the signs of preterm labor?

Additional Reading

By Robin Elise Weiss, PhD, MPH
Robin Elise Weiss, PhD, MPH is a professor, author, childbirth and postpartum educator, certified doula, and lactation counselor.