If you are pregnant, you are carrying a developing baby in your body (and you are definitely a woman). Pregnant women take excellent care of their health — good for them and good for the baby.
Pregnant comes from Latin, and literally means "before giving birth" — prae-, like pre- means "before" and gnasci is a root that means "be born." Pregnant can also mean "filled with something," like inspiration or "rich in significance or implication," like your pregnant pause before answering your friend's question, "You like my new boyfriend, don't you?"