Why do most people say pregnancy lasts 40 weeks when it lasts an average of 38 weeks?

Name: Why do most people say pregnancy lasts 40 weeks when it lasts an average of 38 weeks?
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Question

Quizplus · Accepted Answer

Health professionals measure pregnancy from the first day of the last menstrual period, which is usually about two weeks before conception. Therefore, although the actual time from conception to birth is about 38 weeks on average, pregnancy is measured as lasting 40 weeks from the first day of the last menstrual period.

Why Do Most People Say Pregnancy Lasts 40 Weeks When