Late-term and postterm pregnancy

Last updated: July 20, 2023

Summarytoggle arrow icon

A late-term pregnancy is defined as 41 0/7 to 41 6/7 weeks' gestation; at 42 weeks' gestation, it becomes a postterm pregnancy. While the causes of postterm pregnancy are generally unknown, many supposed cases are likely due to a suboptimally dated gestational age. Risk factors may be maternal (e.g., age, previous postterm pregnancies, nulliparity) and fetal (e.g., male sex, disorders such as oligohydramnios). Patients with low-risk late-term pregnancies who have not had suboptimal gestational dating and who do not have indications for cesarean delivery or contraindications for induction of labor are usually offered the choice between expectant management with antepartum fetal surveillance and induction of labor. After 42 weeks' gestation, induction of labor is recommended regardless of cervical favorability in order to avoid associated complications. Membrane sweeping may be performed in well-dated pregnancies after 39 weeks' gestation to induce labor and prevent late-term or postterm pregnancy.

See also “Pregnancy” and “Prenatal care.”

Definitiontoggle arrow icon

Epidemiologytoggle arrow icon

Epidemiological data refers to the US, unless otherwise specified.

Etiologytoggle arrow icon

Many supposed cases of postterm pregnancy are likely due to suboptimal dating e.g., by using the LMP alone to calculate the EDD. [1][4]

Managementtoggle arrow icon

This applies to patients without high-risk pregnancy, indications for cesarean delivery, or contraindications for induction of labor.

Late-term pregnancy [1][4]

Begin by confirming whether the gestational age and estimated date of delivery for the pregnancy was accurately calculated.

First-trimester prenatal ultrasound is preferred over other methods of determining gestational age and estimated date of delivery. [1][3][5]

Suboptimally dated gestational age [6]

Well-dated gestational age

Offer the following, using a shared decision-making approach:

Management options for low-risk, well-dated late-term pregnancies [1][4][7]
Induction of labor Expectant management
Key points for patient counseling
  • Absolute risk of stillbirth and perinatal mortality is low.
  • No significant difference in risk of maternal complications compared to induction of labor
  • Allows for the possibility of spontaneous labor, which may be preferred by patients
  • Requires ongoing antepartum monitoring
Management steps

Postterm pregnancy [1][4]

After 42 weeks' gestation, induction is recommended regardless of cervical favorability in order to avoid complications of postterm pregnancy. [1]

Complicationstoggle arrow icon

Postterm infant complications [1][3]

Infants born postterm have an increased risk of meconium aspiration syndrome. [1][10]

Maternal complications [1][3]

We list the most important complications. The selection is not exhaustive.

Preventiontoggle arrow icon

Membrane sweeping [1][11][12]

Referencestoggle arrow icon

  1. ACOG. Practice Bulletin No. 146: ACOG Management of Late-Term and Postterm Pregnancies. Obstet Gynecol. 2014; 124 (2): p.390-396.doi: 10.1097/01.aog.0000452744.06088.48 . | Open in Read by QxMD
  2. Mandruzzato G, Alfirevic Z, Chervenak F, et al. Guidelines for the management of postterm pregnancy. J Perinat Med. 2010; 38 (2).doi: 10.1515/jpm.2010.057 . | Open in Read by QxMD
  3. Wang M, Fontaine P. Common questions about late-term and postterm pregnancy. Am Fam Physician. 2014; 90 (3): p.160-5.
  4. Tinofeev, J.. Postterm Pregnancy. Postgraduate Obstetrics & Gynecology. 2011; 31 (18): p.8.doi: 10.1097/01.pgo.0000403873.50475.52 . | Open in Read by QxMD
  5. $Births: Final Data for 2020.
  6. Wheeler V, Hoffman A, Bybel M. Cervical Ripening and Induction of Labor. Am Fam Physician. 2022; 105 (2): p.177-186.
  7. Adams R, Lichorad A, Simmons J. Membrane Sweeping to Decrease Rates of Postdate Induction. Am Fam Physician. 2017; 95 (1): p.35-36.
  8. Methods for estimating due date. Updated: May 1, 2017. Accessed: October 28, 2022.
  9. ACOG. Committee Opinion No. 688: Management of Suboptimally Dated Pregnancies. Obstetrics & Gynecology. 2017; 129 (3): p.e29-e32.doi: 10.1097/aog.0000000000001949 . | Open in Read by QxMD
  10. Philippa Middleton, Emily Shepherd, Jonathan Morris, Caroline A Crowther, Judith C Gomersall. Induction of labour at or beyond 37 weeks' gestation. Cochrane Database Syst Rev. 2020; 2020 (8).doi: 10.1002/14651858.cd004945.pub5 . | Open in Read by QxMD
  11. Caughey AB, Cahill AG, Guise JM, Rouse DJ. Safe prevention of the primary cesarean delivery. Am J Obstet Gynecol. 2014; 210 (3): p.179-193.doi: 10.1016/j.ajog.2014.01.026 . | Open in Read by QxMD
  12. ACOG. Indications for Outpatient Antenatal Fetal Surveillance. Obstetrics & Gynecology. 2021; 137 (6): p.e177-e197.doi: 10.1097/aog.0000000000004407 . | Open in Read by QxMD

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