Pregnancies can also be dated with a physical exam. Publisher's note: Acta Paediatr. This document reflects emerging clinical and scientific advances as of the date issued and is subject to change. Ultrasound dating at 12—14 or 15—20 weeks of gestation? Last menstrual period versus ultrasound for pregnancy dating.
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How Doctors Date Pregnancies, Explained
Because this practice assumes a regular menstrual cycle of 28 days, with ovulation occurring on the 14th day after the beginning of the menstrual cycle, this practice does not account for inaccurate recall of the LMP, irregularities in cycle length, or variability in the timing of ovulation. Subjects Epidemiology Risk factors. Accurate determination of gestational age can positively affect pregnancy outcomes. Support Rewire.