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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.

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week 4 Fetal Development: Week 4
mustard seed
Your Baby is the Size of a Mustard Seed
Month 1 Your Belly This Month
Your Changing Body

You just missed your period and the test came back positive -- that's right, you're pregnant! Can't bear to fasten your bra in the morning? For most women, breast tenderness is the first physical sign of pregnancy -- even before telltale morning sickness strikes.


Your Developing Baby

So what's going on in your womb this week? Your embryo may be minuscule, but trust us: Super-important developments are already under way. This week the embryo splits into two parts. One half will become the placenta, a special tissue that delivers must-have nutrients and oxygen to your baby throughout your entire pregnancy.


Tip of the Week

Don't be surprised if your doctor doesn't schedule an appointment to see you until your 8- to 12-week mark. Many healthcare practices have potential mommies-to-be come in for a blood test with a nurse first to confirm pregnancy.


Your Week 4 To-Do List
woman holding pregnancy test

1. Missed your period? Take a pregnancy test.


An Inside Look
Week 4

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


Your Pregnancy Calendar
Pregnant woman crossing off the days until the birth

Share and celebrate your pregnancy with other moms-to-be.


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 »
More About Your Pregnancy in Week 4
Your Baby
Your Body
  • Your Hormones

    Here come those pregnancy hormones! Find out what you can expect.

  • The Fatigue Factor

    Feeling exceptionally exhausted is a common early-pregnancy symptom. Here's how to manage when you feel less than spunky.

Your Self
  • Handling Work and Fatigue

    Feeling tired during your first few weeks of pregnancy is normal. But how should you handle it at work? Try not to turn to caffeine -- ...

  • Sex During Pregnancy

    Your sex life will likely ebb and flow during pregnancy. Be sure to be both respectful of your partner and vocal of your own needs and ...

Diet & Exercise
  • Dealing with Diabetes

    Are you diabetic? If so, your condition might make your pregnancy more complicated. However, you can lessen the risk to you and your ba...

  • Get Moving

    Although you may not feel like it, getting up and exercising can help you boost your energy. But make sure you know the basics first.

  • Relieving Morning Sickness

    Don't skip out on your exercise regime! Try to get moving, even if your tummy doesn't agree.

Q & A
  • Mom Finds
  • Mom Tools
  • Win
Pregnancy Tools You'll Love
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Get Expert Tips for a Healthy Pregnancy

Our must-read advice for moms-to-be with tips on labor, safety, and more.

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Calculate Your Due Date

Find out when to expect your new arrival.

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29 Pregnancy Charts & Checklists

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