Committee Opinion No. 688: Management of Suboptimally Dated Pregnancies.

The American College of Obstetricians and Gynecologists considers first-trimester ultrasonography to be the most accurate method to establish or confirm gestational age. Pregnancies without an ultrasonographic examination confirming or revising the estimated due date before 22 0/7 weeks of gestation should be considered suboptimally dated. This document provides guidance for managing pregnancies in which the best clinical estimate of gestational age is suboptimal. There is no role for elective delivery in a woman with a suboptimally dated pregnancy. Although guidelines for indicated late-preterm and early-term deliveries depend on accurate determination of gestational age, women with suboptimally dated pregnancies should be managed according to these same guidelines because of the lack of a superior alternative. The best clinical estimate of gestational age should serve as the basis for decisions regarding antenatal corticosteroid exposure in women with suboptimally dated pregnancies who are at perceived risk of preterm delivery. Amniocentesis for fetal lung maturity is not recommended as a routine component of decision making when considering delivery in a woman with a suboptimally dated pregnancy. Late-term delivery is indicated at 41 weeks of gestation when gestational age is uncertain, using the best clinical estimate of gestational age. Initiation of antepartum fetal surveillance at 39-40 weeks of gestation may be considered for suboptimally dated pregnancies. During the antenatal care of a woman with a suboptimally dated pregnancy, it is reasonable to consider an interval ultrasonographic assessment of fetal weight and gestational age 3-4 weeks after the initial ultrasonographic study.