Pregnancy Week 4

Discover your baby's latest fetal developments in week four of your pregnancy and get tips on sharing the exciting news with your friends and family.

Watch Your Baby's Growth

An Embryo Forms: Weeks 4 to 8 of Pregnancy
An Embryo Forms: Weeks 4 to 8 of Pregnancy

Chances are you have no idea you're pregnant yet¿but your body is already hard at work. Watch as the egg undergoes its wondrous transformation to embryo.

Your Changing Body

You'll probably experience breast tenderness around this time, which makes putting a bra on in the morning a chore. You might have a heightened sensitivity to certain smells, too, so be careful about the fragrances you wear and even who you eat lunch next to in the office, because you're more likely to get nauseous from anything too stinky!

Your Developing Baby

Your embryo splits into two parts this week. One becomes the placenta, which will deliver oxygen and nutrients to your baby, and the other is the growing and developing embryo itself.

Your Pregnancy

You missed your period and got two blue lines (or a plus sign, or whatever signal your test gives)--congratulations! You're a mom-to-be!

Your Week 4 To-Do List

1. Missed your period? Take a pregnancy test.

An Inside Look

Take a unique look at Baby's development inside the womb this week.

Your Pregnancy Calendar

Organize your doctor's appointments, save your ultrasound photos, and more--all in one place!

Ask Parents About Week 4

We've got answers to your questions from experts and parents who've been there.

See All Questions or Ask Your Own

Everything in Pregnancy Week 4

More About Your Pregnancy in Week 4

Your Baby

Your Body

Your Self

Diet & Exercise

Q & A