Pregnancy Calendar: 4 Weeks Pregnant

4 Weeks Pregnant
(Counting from the first day of your last menstrual period.)
Size: 1/25 inch
Weight: Less than 1 gram
Pregnancy Week-by-Week

Your Pregnancy: Week 4

Is it? Could it be? Yep. At the very end of this week, which also bizarrely marks the end of your first month of pregnancy, you’ll miss your period. And the ride of your life will begin.

Wondering what’s up with your body, your baby and your life this week? Read on …

What You’re Thinking:

“Instant messages. Instant coffee … Why the heck hasn’t anyone invented an instant pregnancy test?”

Your Body

This is when it all begins.

Once Mini Me or He implants in your uterus and that placenta starts to grow, your heart starts beating more quickly. You might be putting in an extra 15 beats per minute (even when Taye Diggs isn’t onscreen). Until your blood volume catches up to all that extra pumping (which it won’t do for a number of weeks), you’re likely to feel tired most of the time. Sounds like a good reason to schedule a siesta!

A lot of that extra blood is heading straight for your breasts, resulting in tenderness and the tendency for your nipples to show … through your down jacket. (Another early pregnancy sign: Your cervix is softening and changing color. But if this is something you’re able to notice on your own, we don’t want to know about it.)


Your Baby

Your microscopic embryo is already hard at work this week creating the placenta, umbilical cord and the basics of his or her body.

The embryo is now made of three layers that will transform into the different parts of your baby’s body. The endoderm, or inner layer, will become your baby’s intestines, liver and lungs. The middle layer, or mesoderm, will become your baby’s heart, sex organs, muscles, bones, and kidneys, and the ectoderm, or outermost layer, will develop into your baby’s hair, skin, eyes, and nervous system. Believe it or not, your baby is already starting to look like a tiny little being (not necessarily a human being) complete with a head, a mouth opening and a primitive brain and heart.

By the end of this week, your baby measures about 1/25 inch long, about the size of a period (like the one at the end of this sentence, not the one you just missed).

Your Life

You probably can’t wait another second to find out if you’re pregnant. So go ahead and pee on a stick. Just keep a few things in mind:

Despite their advertising, not every pregnancy test is truly sensitive enough to pick up a pregnancy 30 seconds after you miss your period. Different home pregnancy tests pick up different levels of the pregnancy hormone hCG. So don’t despair if you get an initial negative. If Aunt Flo doesn’t show up in a day or so, test again.

Your best chance of “passing” this test is to wait as long as you can stand it, and to use your more concentrated morning urine.

Once it’s official, you get to come up with a fun way to share the test results (if you didn’t have people gawking over your shoulder while you were taking it, that is). Some mamas-to-be go to elaborate lengths to share the big news. (Billboard on I-95 anyone?) But no matter how grand or matter-of-fact the gesture, this should be about you sharing your excitement with the people you care about; the ones who are going to be supporting you (and, yes, putting up with you) for the next nine months.

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