Sex is set at conception, but boys' and girls' genitals look the same until 9 weeks, when big changes start. BabyCenter's editorial team is committed to providing the most helpful and trustworthy pregnancy and parenting information in the world.
When creating and updating content, we rely on credible sources: respected health organizations, professional groups of doctors and other experts, and published studies in peer-reviewed journals. We believe you should always know the source of the information you're seeing. Learn more about our editorial and medical review policies. American Academy of Family Physicians.
Prenatal development: How your baby grows during pregnancy. American College of Obstetricians and Gynecologists. Mayo Clinic. Fetal development: The 2nd trimester. Fetal development. Inside pregnancy: Girl or boy? Medically reviewed by Jacqueline Dela Merced, M. Video note: Contains medically accurate illustrations. Advertisement page continues below.
Opens a new window Opens a new window Opens a new window. Inside pregnancy: Weeks 1 to 9 min. Inside pregnancy: Weeks 10 to 14 min. Inside pregnancy: Weeks 15 to 20 min. Inside pregnancy: Weeks 21 to 27 min. Inside pregnancy: Weeks 28 to 37 min. Your baby's senses during pregnancy min. How your body changes during pregnancy min. Show more. Where to go next. Your baby's senses during pregnancy. Inside pregnancy: Weeks 21 to When do your baby's sex organs develop in the womb?
How your body changes during pregnancy. Inside pregnancy: Weeks 15 to Inside pregnancy: Weeks 28 to Inside pregnancy: Weeks 10 to Inside pregnancy: Weeks 1 to 9.
