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Ob-Gyns Redefine Meaning of "Term Pregnancy"

Definition Change Will Benefit Newborn Health and Data Collection

October 22, 2013

Washington, DC -- The nation’s ob-gyns have redefined ‘term pregnancy’ to improve newborn outcomes and expand efforts to prevent nonmedically indicated deliveries before 39 weeks of gestation. In a joint Committee Opinion, The American College of Obstetricians and Gynecologists (The College) and the Society for Maternal-Fetal Medicine (SMFM) are discouraging use of the general label ‘term pregnancy’ and replacing it with a series of more specific labels: ‘early term,’ ‘full term,’ ‘late term,’ and ‘postterm.’ 
The following represent the four new definitions of ‘term’ deliveries:

  • Early Term:  Between 37 weeks 0 days and 38 weeks 6 days
  • Full Term:    Between 39 weeks 0 days and 40 weeks 6 days
  • Late Term:   Between 41 weeks 0 days and 41 weeks 6 days
  • Postterm:     Between 42 weeks 0 days and beyond

Calendar“This terminology change makes it clear to both patients and doctors that newborn outcomes are not uniform even after 37 weeks,” said Jeffrey L. Ecker, MD, chair of The College’s Committee on Obstetric Practice. “Each week of gestation up to 39 weeks is important for a fetus to fully develop before delivery and have a healthy start.”

On average, a pregnancy with a single fetus lasts 40 weeks from the first day of the last menstrual period. This calculation determines a pregnant woman’s estimated date of delivery (EDD). Previously, babies were considered ‘term’ if they were born anytime between three weeks before and two weeks after the EDD (37–42 weeks of gestation). “Until recently, doctors believed that babies delivered in this five-week window had essentially the same good health outcomes,” said Dr. Ecker.

Research over the past several years, however, shows that every week of gestation matters for the health of newborns. The last few weeks of pregnancy within these 40 weeks allow a baby’s brain and lungs to fully mature. Babies born between 39 weeks 0 days and 40 weeks 6 days gestation have the best health outcomes, compared with babies born before or after this period. This distinct time period is now referred to as “Full Term.”

Planned deliveries before 39 weeks 0 days should occur only when there are significant health risks to a woman and/or the fetus in continuing the pregnancy, according to Dr. Ecker. Sometimes delivery before 39 weeks 0 days is unavoidable, such as when a woman’s water breaks or contractions come early. 

The College and SMFM encourage physicians, researchers, and public health officials to adopt these new precisely-defined terms in order to improve data collection and reporting, clinical research, and provide the highest quality pregnancy care.

Committee Opinion #579 “Definition of Term Pregnancy” is published in the November issue of Obstetrics & Gynecology.

See Committee Opinion #561 “Nonmedically Indicated Early-Term Deliveries.”

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For more information on The College’s partnership with the US Department of Health and Human Services “Strong Start” public awareness campaign to reduce unnecessary elective deliveries before 39 weeks’ gestation, visit

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Other recommendations issued in November’s Obstetrics & Gynecology:

Committee Opinion #577 “Understanding and Using the US Selected Practice Recommendations for Contraceptive Use” (NEW!)

ABSTRACT: The U.S. Selected Practice Recommendations for Contraceptive Use, 2013 (U.S. SPR), issued by the Centers for Disease Control and Prevention is a companion piece to the Centers for Disease Control and Prevention’s U.S. Medical Eligibility Criteria for Contraceptive Use, 2010. The U.S. Medical Eligibility Criteria for Contraceptive Use, 2010, provides guidance for which contraceptive methods are safe for women with selected characteristics and medical conditions, whereas the U.S. SPR offers guidance on how to use these methods most effectively. The American College of Obstetricians and Gynecologists endorses the U.S. SPR and encourages its use by Fellows; providers should always consider the specific clinical situation when applying these guidelines to individual clinical care.

Committee Opinion #578 “Elective Surgery and Patient Choice” (Revised)

ABSTRACT: Acknowledgment of the importance of patient autonomy and increased patient access to information, such as information on the Internet, has prompted more patient-generated requests for surgical interventions not traditionally recommended. Depending on the context, acceding to a request for a surgical option that is not traditionally recommended can be ethical. Decisions about acceding to patient requests for nontraditional surgical interventions should be based on strong support for patients’ informed preferences and values; understood in the context of an interpretive conversation; and consistent with considerations of safety, cost-effectiveness, and attention to effects on the health care system of expanded choice. Physicians should make sure that their counseling about specific risks and benefits is based on current evidence. After the physician has provided information and careful counseling, the patient and physician will often reach a mutually acceptable decision. If the patient and physician cannot reach an agreement, then referral or second opinion may be appropriate.

The American College of Obstetricians and Gynecologists (The College), a 501(c)(3) organization, is the nation’s leading group of physicians providing health care for women. As a private, voluntary, nonprofit membership organization of approximately 57,000 members, The College strongly advocates for quality health care for women, maintains the highest standards of clinical practice and continuing education of its members, promotes patient education, and increases awareness among its members and the public of the changing issues facing women’s health care. The American Congress of Obstetricians and Gynecologists (ACOG), a 501(c)(6) organization, is its companion organization.

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The Society for Maternal-Fetal Medicine (est. 1977) is a non-profit membership group for obstetricians/gynecologists who have additional formal education and training in maternal-fetal medicine. The society is devoted to reducing high-risk pregnancy complications by providing continuing education to its 2,000 members on the latest pregnancy assessment and treatment methods. It also serves as an advocate for improving public policy, and expanding research funding and opportunities for maternal-fetal medicine. The group hosts an annual scientific meeting in which new ideas and research in the area of maternal-fetal medicine are unveiled and discussed. For more information, visit or