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Now a pregnancy test can maybe reveal if you are pregnant or not. Nervous? You’re not alone!
It can be too early to tell too. But even if you still haven’t gotten a positive pregnancy test result, you may notice other early signs of pregnancy..

Inside your body, your baby may be implanting in your uterus, and in such a case, you are really pregnant!

This article will cover fetal development, how big your baby is, pregnancy symptoms, and what’s happening with your body, mom.

Week 3 | Week 5


4 weeks pregnant what to expectPin

What to Expect When 4 Weeks Pregnant?

How Many Months is 4 Weeks Pregnant?

When you are 4 weeks pregnant, you are in your first trimester and the first month of pregnancy.

Pregnancy lasts 9 months, or 40 weeks, which is divided into three trimesters. Because pregnancy weeks don’t fit perfectly into months, it is more common to talk in weeks when talking about pregnancy.

However, you’ll often get asked how many months pregnant you are or what month of pregnancy you are in. There is a difference between the two, and it might seem a bit confusing. To help you understand it better, we wrote a post about counting pregnancy weeks and months.

Your Baby’s Development

How Big is my Baby at 4 Weeks?

baby fruit size pregnancy week 4 poppy seedPin
implantation 4 weeks pregnantThe fetal age of your baby is now 2 weeks. You can rejoice in the fact that your new little one has graduated to an embryo this week!

Even though a lot is going on and the embryo is developing very quickly, your baby-to-be is only the size of a poppy seed at this point, so there is not a whole lot to see with the naked eye.
You’ll find a handy (and cute!) chart for baby size by pregnancy week here.

What Does my Baby Look Like at 4 Weeks Pregnant?

Your little embryo has two layers of cells, the epiblast and the hypoblast, that will, later on, develop into the essential organs and body parts that your baby requires to function on their own.

Fetal development

embryo at 4 weeks pregnantPinAt some point this week, implantation occurs. The average day for this to happen is 9 days after ovulation.

This week is a busy time as the amnion and the yolk sac are maturing for your baby’s use. The amnion is filled with amniotic fluid that surrounds and protects your little embryo. The yolk sac produces the blood and nourishes it until the placenta is able to take over this vital role in development. The yolk sac will later become incorporated into your baby’s developing digestive tract.

The endometrium is crucial for your egg since it uses it for nutrition and for taking away waste material during development.

The implantation site, where your egg attaches to the uterine wall, will eventually develop into the placenta essential for your baby’s development in pregnancy. During this time, your body produces the hormone hCG (human chorionic gonadotropin) that will let your body know to stop releasing eggs and begin producing estrogen and progesterone. With the increasing levels of hCG, you may even be able to get a positive result on a pregnancy test at this point.

Mom’s Body When 4 Weeks Pregnant

The Belly

4 weeks pregnantPinAt this point, your belly might be a bit bloated, but you are still weeks away from actually seeing your belly growing. Considering that your baby is as big as a poopy seed, this shouldn’t be much of a surprise.

There will be plenty of time for you to grow and see for yourself exactly how much space your new addition is going to require.

If you are one of the lucky ones to have a multiple-pregnancy in the works, you will see the signs of growth sooner than you imagine since there is 1 (or 2!) more to nourish and grow during this time.


Pregnancy Symptoms

Some women will experience slight cramping and even spotting during this week and can mistake these early pregnancy symptoms for the beginning of their monthly period.

Another symptom that might make you think your period is near is your breasts being sore and tender.

Early pregnancy symptoms are often the same as premenstrual symptoms. Because of it, many women first suspect they might be pregnant only when their period doesn’t arrive. It is still early, so it is not unusual if you don’t experience or notice any symptoms at this point, especially if you are a first-time mom.

Around the time of implantation, when the fertilized egg attaches to the lining of the uterus, implantation bleeding might happen. Implantation bleeding or spotting is light, usually consisting of a few drops of blood. It lasts for 1-2 days, is usually light pink, light red, or light brown in color, and occurs earlier than your period would.

It is not a sign that something is wrong, so don’t worry if you experience it. However, only 25 percent of women experience it, so there is a high chance you won’t even notice anything happening when the implantation occurs.

Mothers of multiples tend to have stronger symptoms due to their bodies working overtime to produce hormones essential for the development of their little ones.

Extreme nausea, fatigue, and even breast soreness are hard to ignore for those carrying more than one embryo during this time.

Things to Do and Buy This Week

When you are 4 weeks pregnant, you might get a positive pregnancy test result. However, many women will have to wait a few more days. If your embryo implanted late, it may take a few more days or even a week before your hCG levels have risen enough to make the test come out positive.

If your pregnancy test has come back positive, then you will want to make an appointment with your medical practitioner as soon as possible.

Typically, your first prenatal appointment will happen around 8 weeks of pregnancy unless you have experienced previous problems with pregnancies or are in a high-risk category.

This is a good time to discuss with your doctor any medication that you currently take or occasionally take since many over-the-counter medications are not recommended for pregnant or nursing mothers.

Sleep is crucial for expecting mothers, no matter what age or where they are in their gestation period. Be sure to not only get all the vitamins and nutrients needed for your developing baby but also get enough rest as your body is working extremely hard to prepare the groundwork for your little one, who will rely on you for all of its needs in the coming months.

Week 4 Video

4 Weeks Pregnant - What to Expect

Diary of a Daughter

What’s it really like being 4 weeks pregnant…? Here’s a true diary from a 4 weeks pregnant mom (Me..!)

No signs of menstruation. BBT is staying high and increasing. This is so exciting. But also so scary to start hoping again. I’m only a few days from a pregnancy test now.

Are you also 4 weeks pregnant? Let’s create a pregnancy diary together! Please share your experiences and thoughts by leaving a comment below!

More About Early Pregnancy

4 weeks pregnant infoPin


Mayo Clinic, Mayo Clinic Guide to a Healthy Pregnancy
Joanne Stone MD and Keith Eddleman MD, The Pregnancy Bible: Your Complete Guide to Pregnancy and Early Parenthood
Nilsson, L; Hamberger, L. A Child Is Born
Soderberg, L., Mammapraktika. B Wahlstroms.

Image: Image of 4 weeks embryo thanks to the Science Museum

Week 3 | Week 5


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