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Stages of Pregnancy Week by Week

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.

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week 1

Your baby grows from the size of a tiny seed to a watermelon in just 40 weeks.

Month 1

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.

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Your Changing Body

For most women, trying to conceive means making a few smart lifestyle swaps -- all in the name of conceiving the healthiest baby possible. So now is the time to start thinking about any health changes you could make to ensure that your body is in the best shape for carrying and nurturing your baby.

Your Developing Baby

Baby? What baby? This concept may be a little hard to wrap your head around, but even though you're technically in the first week of pregnancy, you're not quite expecting -- yet.

Tip of the Week

Speak with your doctor about adding a prenatal multivitamin to your morning routine. At least 400 micrograms of folic acid every day can help prevent certain birth defects that affect your baby's brain, heart, and spinal cord, especially if you take it before you conceive and in the early weeks of your pregnancy

woman holding glass of water and prenatal vitamin

Your Week 1 To-Do List

1. Start taking a prenatal vitamin.

pregnancy test

An Inside Look

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

Pregnant woman crossing off the days until the birth

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

  • Your Partner: How Men React to Pregnancy

    Your partner may not react to your good news in the same way as your girlfriends. Find out why sometimes there is a difference -- and t...

  • Telling Your Partner

    Time to share the good news with your partner? Read this before you make the big announcement for solid pointers and helpful advice.

Diet & Exercise

  • Smoking and Alcohol Use

    Smoking and drinking alcohol during pregnancy is a big no-no. But do you know why? Find out what this can do to your baby.

  • Prenatal Vitamins

    Taking a prenatal vitamin is an essential part of early pregnancy.

Q & A

First Trimester

Second Trimester

Third Trimester