When does labor usually start?

For most women, labor begins sometime between week 37 and week 42 of pregnancy. Labor that occurs before 37 weeks of pregnancy is considered premature, or preterm.1

Just as pregnancy is different for every woman, the start of labor, the signs of labor, and the length of time it takes to go through labor vary from woman to woman and even from pregnancy to pregnancy.


  1. Fleischman, A. R., Oinuma, M., & Clark, S. L. (2010). Rethinking the definition of “term pregnancy.” Obstetrics and Gynecology, 116(1), 136–139.
  2. American College of Obstetricians and Gynecologists. (2011). FAQ: How to tell when labor begins. Retrieved February 13, 2017, from http://www.acog.org/Patients/FAQs/How-to-Tell-When-Labor-Begins
  3. American College of Obstetricians and Gynecologists. (2016). FAQ: Preterm (premature) labor and birth. Retrieved July 17, 2017, from https://www.acog.org/Patients/FAQs/Preterm-Labor-and-Birth
  4. American College of Obstetricians and Gynecologists. (2012). FAQ: Labor induction. Retrieved February 13, 2017, from http://www.acog.org/Patients/FAQs/Labor-Induction
  5. National Child and Maternal Health Education Program. (2013). Moms-to-be: Let baby set the delivery date. Retrieved February 13, 2017, from https://www.nichd.nih.gov/ncmhep/initiatives/is-it-worth-it/Pages/moms.aspx
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