Pregnancy Week 1

Learn what's happening in week one, even before your baby is conceived, and find out why your due date is calculated from this point on.

Your Developing Baby

In the first week of your pregnancy, there's no baby--yet! But a growing fetus will be there very soon.

What My Baby Looks Like

How Big Is Baby This Week?

Watch Your Baby's Growth

Sperm Meets Egg: Weeks 1 to 3 of Pregnancy
Sperm Meets Egg: Weeks 1 to 3 of Pregnancy

Something magical is about to happen! Watch as the ovulation process occurs, and then millions of sperm swim upstream on a quest to fertilize an egg.

Your Changing Body

You probably don't know you're pregnant (or rather, about to be!), but you're well on your way. Your conception date is considered to be two weeks after the last day of your last menstrual period.

You won't notice anything yet, but if you're trying to conceive and think it's about to happen, nix alcohol and smoking and replace those vices with prenatal vitamins.

Your Pregnancy Calendar

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

Ask Parents About Week 1

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 1

More About Your Pregnancy in Week 1

Your Baby

Your Body

Your Self

Diet & Exercise

Q & A