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About Pregnancy

Pregnancy is the term used to describe the period in which a fetus develops inside a woman’s womb or uterus.

Pregnancy usually lasts about 40 weeks, or just over 9 months, as measured from the last menstrual period to delivery. Health care providers refer to three segments of pregnancy, called trimesters. The major events in each trimester are described below.1

  • First Trimester (Week 1 to Week 12)

  • Second Trimester (Week 13 to Week 28)

  • Third Trimester (Week 29 to Week 40)

Citations

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  1. Office on Women’s Health. (2010). Stages of pregnancy. Retrieved May 20, 2016, from http://womenshealth.gov/pregnancy/you-are-pregnant/stages-of-pregnancy.html [top]
  2. American College of Obstetricians and Gynecologists (ACOG). (2015, June). Prenatal development: How your baby grows during pregnancy. Retrieved May 20, 2016, from http://www.acog.org/~/media/For%20Patients/faq156.pdf?dmc=1&ts=20120731T1026504777 External Web Site Policy (PDF - 70 KB) [top]
  3. Stoll, B. J., Hansen, N. I., Bell, E. F., Shankaran, S., Laptook, A. R., Walsh, M. C., et al. (2010). Neonatal outcomes of extremely preterm infants from the NICHD Neonatal Research Network. Pediatrics, 126, 443–456. PMID: 20732945 [top]
  4. Spong, C. Y. (2013). Defining “term” pregnancy: Recommendations from the Defining “Term” Pregnancy Workgroup. JAMA, 309(13), 2445–2446. Retrieved October 28, 2013, from http://jama.jamanetwork.com/article.aspx?articleID=1685467 External Web Site Policy [top]
  5. Centers for Disease Control and Prevention. (n.d.). CDC WONDER: About natality, 2007-2014. Retrieved May 20, 2016, from http://wonder.cdc.gov/natality-current.html [top]
  6. ACOG Committee on Obstetric Practice and Society for Maternal-Fetal Medicine. (2013; Reaffirmed 2015). Committee Opinion No. 579. Definition of term pregnancy. Retrieved May 20, 2016, from http://www.acog.org/Resources_And_Publications/Committee_Opinions/
    Committee_on_Obstetric_Practice/Definition_of_Term_Pregnancy
     External Web Site Policy [top]
  7. NICHD. (2013). Carrying pregnancy to 39 weeks: Is it worth it? Yes! Retrieved July 8, 2016, from https://www.nichd.nih.gov/news/resources/spotlight/Pages/013113-NCMHEP-videos.aspx [top]
  8. NICHD. (2013). Redefining the term. Retrieved July 8, 2016, from https://www.nichd.nih.gov/news/resources/spotlight/Pages/102413-redefining-term.aspx [top]

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