pregnant week 4

Pregnancy Guide: Week 4

At 4 weeks pregnant you still have an embryo with two sets of cells, which will eventually become the placenta and the fetus. If you’re having twins, there are already two distinct embryos, and you would be able to see them on an ultrasound. What will soon become the placenta is now a yolk sac that produces blood to nourish the embryo.

4 weeks pregnant is how many months?

You’re finally one month pregnant, and you’re likely just finding that out with a positive pregnancy test or a missed period. You only have eight more months to go by the time one month has passed.

Your Baby at 4 Weeks

By the time you know you’re pregnant, your embryo has found its home for the next eight months in your uterus. That migratory blastocyst made its way up the fallopian tube and implanted at its destination. It will now burrow into the lining and implant itself, so it can’t escape until it’s good and ready.

The final separation of cells will occur now, and one will become a baby and the other a placenta. That placenta will continue to supply blood and nutrients to your baby for the next thirty-six weeks.

Your embryo is tiny, but it’s a powerhouse. The amniotic sac is beginning to develop around it, which will protect it while it’s in your uterus. The fluid in the amniotic sac is what you will see in just a short eight months’ time when your water breaks.

The embryo has three sets of cells now instead of two. These will form your baby’s body parts. 

  • The inner layer is called the endoderm, and it will become your baby’s liver, lungs, and digestive system. 
  • The middle layer is the mesoderm and it will be your baby’s bones, sex organs, kidneys, heart, and muscles. 
  • The outer layer is the ectoderm and will be your baby’s hair, eyes, skin, and nervous system.

How big is a baby at 4 weeks?

Your baby is the size of a poppy seed. Think about those little things in your muffin or on top of your bagel. It is about one millimetre long and still weighs something that’s almost impossible to measure.

Your Body at 4 Weeks

You may feel more in tune to your body than ever at this point, or you may feel like it’s no longer yours. Your raging hormones will make you feel different, despite the fact that there’s nothing visible happening on the outside. Some women don’t feel a thing or have no idea they’re pregnant, while others will have some PMS-like symptoms as if they are signalling their next period.

Whether you know you’re pregnant or not, a lot is going on. Your embryo is attaching to your uterus, and in about one-third of women, spotting will occur at this phase. There’s nothing wrong if this happens. 

Pressure in your abdomen is also normal as your uterus grows to accommodate the embryo. You may also experience breast tenderness, but much more of that will come later as your breasts prepare to breastfeed. Soon, a pregnancy hormone will light up your test as the egg releases a hormone called hCG.

If you know you’re pregnant by now, you can start planning your due date. Just count forty weeks from the start of your last period. Keep in mind that your due date is just an estimate. Don’t go planning your maternity leave just yet.

The typical pregnancy lasts forty weeks, but if your baby is born on his due date, he will have only been in utero for thirty-eight. That’s because you start counting the forty weeks from two weeks before you’ve actually conceived. Some babies don’t make an appearance until forty-two weeks, and that’s totally normal, too.

pregnant week 4


You may experience some implantation bleeding during this week. It’s right on schedule for your next period, so you may not suspect anything out of the ordinary. But it’s not your period at all, it’s a new baby. 

Don’t panic—it is completely normal. If you don’t have spotting, you may suspect you’re pregnant by a missed period, and it’s also normal for most women not to have any bleeding at all. The moral of the story is, you’re normal no matter what.

PMS-like symptoms are normal at this stage, too, which may again cause you to suspect your next period. The hormones surging through your body can cause all kinds of aches and pains, fatigue, mood swings, bloating, cramping, and cravings. This is only the first you’ve heard of these hormones, so get used to them, because they’ll be with you for the next eight months.

Tips/Things to do

Get plenty of vitamin D. Go outside or drink some milk, because your baby needs this for healthy developing bones and teeth. Getting a good supply of vitamin D can also help your body absorb more calcium, which your baby needs to develop healthy bones and organs. 

If you don’t like milk, you can get vitamin D from fortified orange juice, egg yolks or canned sardines.

Calculate your due date. It will give you a better idea of when your baby might make an appearance. You can’t set your watch to it, but you can anticipate the day and know it will be sometime within a few weeks of that date.

Avoid smoking and secondhand smoke. Even if you don’t smoke, you need to stop hanging with people who do. It can increase your risk for low birth weight, ectopic pregnancy, miscarriage, and other complications.

Eat plenty of healthy fats. Omega-3 fatty acids are essential to brain and retina development. Your baby needs plenty of DHA, one of the omega-3s, to assist in growing. Eat anchovies, trout, wild salmon, sardines, walnuts, and flaxseed.

Go swimming. It’s a safe, fun, low-impact activity that has great benefits for you and baby. You’ll feel weightless in the water no matter how big you get and it’s an aerobic exercise that increases your ability to use oxygen effectively. It can improve circulation, muscle tone, and endurance. Swimming for twenty minutes three times a week will help you sleep better and feel less tired. There are also other exercises that may be good to try while pregnant. For example, good ab exercises while pregnant.

Most importantly, make your first appointment with your doctor. Even if they ask you to wait a few more weeks, get something on the calendar as soon as you have a positive test, so you get the care you and your baby need.

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