Accuracy
Calculations of gestational age from LMP are sometimes incorrect due to normal variation from the average ovulation date. The gestational age of an individual infant can be more accurately estimated from:
- The woman's knowledge of the date of sexual intercourse.
- The woman's knowledge of fertility signs related to ovulation. The needed observations are normally made by women who use fertility awareness methods to get pregnant.
- Examination of the newborn infant. In the twentieth century, doctors (especially pediatricians) were trained to recognize the physical changes occurring to the fetus in the latter half of pregnancy so that a maturational age could be estimated.
- An obstetric ultrasound ("dating scan", in the UK routinely offered around 12 weeks) during the pregnancy, whereby sizes of certain fetal body parts are measured.
The fertilization age of children conceived by in vitro fertilization is known to the hour.
Read more about this topic: Gestational Age
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