Despite the Fact That a Human Female Has a Normal

Multiple Choice

Despite the fact that a human female has a normal pregnancy duration (or gestational period) of 38 weeks, people often refer to pregnancy as a 40-week event. Why is this?

A) ​Because the heightened influence of teratogens in the world today has actually extended the duration of pregnancy from conception to delivery.
B) ​Because pregnancy usually begins two weeks after a woman's menstrual period, and that is the time from which the beginning of pregnancy is measured.
C) ​Because the duration of pregnancy actually gets longer as a woman ages, and it ranges from 38 to 42 weeks. 40 weeks is the average, so that is what people say.
D) ​Because physicians want to allow for a two-week "window" at the end of the pregnancy so that women do not become concerned if they have not delivered by the end of the 38th week.