What is the typical duration of pregnancy in humans from conception to birth?

The typical duration of pregnancy in humans from conception to birth is approximately 9 months, which is around 40 weeks. This period is measured from the first day of the last menstrual period, as this provides a clear starting point for tracking gestational age. During these 9 months, the embryo develops into a fetus, and numerous significant changes occur in both the mother and the developing baby.

The 9-month timeframe allows for essential developmental stages, including organ formation, growth, and the maturation of body systems necessary for the newborn to survive outside the womb. This period of development is critical for ensuring a healthy pregnancy outcome, as various factors, including maternal health and prenatal care, influence both the duration and the success of the pregnancy.

In contrast, the other durations provided are insufficient for a full-term human pregnancy. A duration of 6 weeks represents only the first trimester, while 15 weeks is still in the early stages of pregnancy, and 12 months exceeds the typical range, as a full-term pregnancy does not extend beyond approximately 10 months.