Pregnancy Week By Week
4 weeks pregnant illustration
BABY IS AS BIG AS A
POPPYSEED!

4 Weeks Pregnant

Congratulations! If you know you're 4 weeks pregnant, you found out the news earlier than a lot of women do (because you took a test as soon as you missed your period, or even a few days before, instead of waiting a bit). You might be totally excited, or you might be getting used to the idea of having a baby. Either way, you may not be feeling any different (for now, at least), since early pregnancy symptoms don’t always kick in right away. Definitely celebrate this amazing news with your partner, but you may not want to tell the whole world just yet. Your first call at week 4 of pregnancy should be to your doctor to schedule your first prenatal visit, where they will confirm your pregnancy with a urine or blood test. For updates on what’s happening with you and baby throughout your pregnancy, sign up for The Bump pregnancy week-by-week newsletter emails.

How Big Is Baby at 4 Weeks Pregnant?

At 4 weeks pregnant, baby is smaller than a poppy seed—practically microscopic. Baby is now known as a blastocyst, a teeny ball of cells, and is busy settling into their new home (your uterus), prepping for all the crucial development that will happen over the next six weeks.

4 Weeks Pregnant Symptoms

The same pregnancy hormones that gave you that positive pregnancy test can also cause some of the more typical 4-week pregnancy symptoms. These hormone levels increase pretty quickly, so while it’s normal to be 4 weeks pregnant with no symptoms, brace yourself: nausea and vomiting may be in your near future. Here’s a bit of what to expect at 4 weeks pregnant:

  • Bloating. You may be a little puffed up thanks to the pregnancy hormone progesterone. Break out the comfy pants!
  • Mild cramping. At 4 weeks pregnant, cramping might worry you, but it actually may be a sign that baby has properly implanted in the lining of your uterus. However, any severe cramping or pain at 4 weeks pregnant is something you should definitely tell your doctor about right away, since they’ll want to examine you to rule out any problems.
  • Spotting. Light bleeding can also occur during week 4 as a result of implantation. Don't worry—this is totally normal too. But the same advice goes: If it’s a lot of blood, like a period or heavier, lasts for more than a couple days, or if you’re concerned in any way, see the doctor.
  • Mood swings. It’s not your imagination. Your mood is going haywire mostly because of your fluctuating hormones. (But maybe also because of stress and because your mind is racing.) Pregnancy mood swings are most drastic during the first 12 weeks. After that, the hormones will level out a bit, making you less likely to cry at every life insurance commercial you see.
  • Morning sickness. Experts say that about 50 to 90 percent of pregnant women get some form of morning sickness (aka nausea and sometimes vomiting too). So even if you haven’t had an upset stomach yet, you probably will at some point. Morning sickness is usually at its worst around nine weeks and then slowly gets better, typically disappearing completely in the second trimester.
  • Fatigue. One of the most common 4 weeks pregnant symptoms is total exhaustion, as your body is working hard to grow that teeny ball of cells into an embryo.
  • Sore breasts. Yowch! Your breasts are swollen and tender because of those surging hormones telling your body, “There’s a baby coming. Better start prepping those milk ducts!”

Is it normal to be really tired at 4 weeks pregnant?

It’s totally normal to be completely worn out and feel like you need a nap after tying your shoes at 4 weeks pregnant. Fatigue is one of the main symptoms of early pregnancy, and it’s no wonder—you’re growing a brand new person inside your body! Get in the habit of going to bed early and napping when you can.

4 Weeks Pregnant Belly

A 4 weeks pregnant belly might be a little bloated, but you almost certainly don’t look pregnant yet. Still, you need to start acting like a mom-to-be—and that means giving TLC to yourself and your tiny baby-to-be.

Baby is already undergoing important development at week 4 of pregnancy, so start taking a prenatal vitamin if you’re not already. Look for one with at least 400 micrograms of folic acid and remember to take it daily. We know you’ve got a lot on your mind, but since folic acid is proven to help prevent birth defects, this is super-important!

As your skinny jeans get more difficult to button, don’t shy away from looser clothing styles. Think: stretchy pants, leggings, drapey shirts and waterfall cardigans. There are a ton of loose-fitting clothing options that will help you look stylish and stay comfy.

4 Weeks Pregnant Ultrasound

During week 4 of pregnancy, the ball of cells is splitting into the embryo (your future child) and placenta. Baby's neural tube, the building block of the spine, brain and backbone, is already formed. The amniotic sac and fluid are forming into protective cushioning for baby. And on a 4 weeks pregnant ultrasound, all of that just looks like a tiny dot, called the gestational sac.

Chances are, though, you won’t have an ultrasound at 4 weeks. When you call the OB to tell them you’re 4 weeks pregnant, they might tell you congrats and then have you make your first prenatal appointment for about a month from now.

We know it seems like an eternity to wait. But if you have a clean bill of health and no risk of pregnancy complications, there simply isn’t a need to be seen by a doctor just yet. There will be much more for the OB to see (including a heartbeat!) around week 8 or 9. In the meantime, eat well, drink lots of water, avoid unhealthy habits like drinking and smoking and try to relax.

Is there a heartbeat at 4 weeks pregnant?

At 4 weeks pregnant, your little blastocyst doesn’t have a heartbeat quite yet. A blood vessel has begun to form, which will become the heart and circulatory system in the next several weeks. The heart will continue to develop until the 10th week but will begin to beat in the 5th or 6th week.

Tips for 4 Weeks Pregnant

Get around a queasy tummy
Around 4 weeks pregnant, you may be just starting to feel nauseous and experience aversions to certain foods, smells and textures. If that’s the case, start eating a snack first thing in the morning and consider asking your partner to prepare food for you so you don’t feel sick before it’s even time to eat.

Switch when you take your vitamin
Continuing to take your prenatal is important, particularly if you’re having trouble consistently eating well because of nausea. Unfortunately, some people find that taking their prenatal vitamin in the morning or during the day can send an already queasy tummy over the edge. If your prenatal is making your morning sickness (or all day sickness) worse, try taking it with a small snack before bed, or split your dose so you take half in the morning and half at night.

Get your vitamin D
Both you and baby need vitamin D to support calcium absorption and help build (or maintain!) healthy teeth and bones. Try getting at least 15 minutes of sun everyday to start, then look to your diet. Fortified milk products, eggs, sardines and salmon are all excellent sources of vitamin D. Fortified breakfast cereal can also be a good source (especially when you eat it with milk).

Sneak healthy foods into yummy snacks
Still having trouble stomaching the wholesome foods you need for a healthy pregnancy and baby? Hide ’em! Try sneaking dark, leafy greens into fruit smoothie with blueberries, mango and banana. Ground or finely chopped meat can be hidden in saucy dishes. Tofu can be blended into a multitude of recipes. Get creative with incorporating healthy ingredients in sneaky ways, and you just might be able to get the nutrients you need without even noticing.

Pregnancy Checklist at 4 Weeks Pregnant

Reminders for the week:

Medical content was reviewed November 2020 by Sara Twogood, MD, an ob-gyn at Cedars Sinai Medical Center in Los Angeles and author of Ladypartsblog.com.

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