Only 4 percent of women give birth on their estimated delivery date. That’s because of the natural variation in how long it takes a baby to grow and because of our limited ability to predict due dates.
Medicine, it turns out, is surprisingly bad at measuring the precise age of a fetus or how far along a woman is into her pregnancy.
Having concrete information about a baby’s “gestational age” wouldn’t just help moms plan their pregnancies. It would also help doctors better determine whether a fetus is developing as it should, and what extra care may be needed for safer births. Doctors also have no way of accurately predicting whether a baby might arrive too early — a leading cause of infant death globally.
(Click link at top to read on vox.com)