Table 2.

Acceptable Criteria for Confirmation of Gestational Age

Clinical Criteria

≥ 39 weeks of gestation have elapsed since the first day of the last normal menstrual period in a woman with a regular menstrual cycle and no immediate antecedent use of oral contraceptives.  Fetal heart tones have been documented for ≥ 20 weeks’ gestation by nonelectronic fetoscope or for ≥ 30 weeks by Doppler ultrasound.

Laboratory Criteria

≥ 36 weeks of gestation have elapsed since a positive serum beta human chorionic gonadotropin pregnancy test result.  Ultrasound estimation of gestational age is considered accurate if (a) it is based on crown-rump measurements obtained at 6–11 weeks’ gestation or (b) it is based on biparietal diameter measurements obtained before 20 weeks’ gestation.

Data from The American College of Obstetricians and Gynecologists.⁴