Monkeys, like humans, are primates. As such, they are very closely related to our species, as well as apes such as chimpanzees, orangutans and gorillas. Accordingly, many similarities exist between humans and monkeys in terms of pregnancy, labor and and the delivery of newborns.
Sex and Gestation
As with other mammals, a female monkey becomes pregnant through sexual intercourse with a male monkey. Monkeys are also among the only animals besides humans believed to have sex for pleasure rather than for purely reproductive purposes. Whereas the gestation period for humans is about nine months, that of monkeys is about five and a half months, with the difference probably due chiefly to the difference in body size.
Mechanics of Delivery
Owing to the shape of the human female pelvis, human babies are usually born with the newborn facing away from the mother. Monkeys do not walk upright, so their pelvises are structurally different from that of humans; as a result, their babies are born facing the mother. This has several advantages -- for example, the mother can help pull the newborn out of the birth canal and untangle the umbilical cord if necessary.