4 Weeks Pregnant

At 4 weeks pregnant, the first part to form in the baby is the neural tube¹. It develops into the spine and brain. This is the structure from which the whole body forms; we can say this is the key week, and the proper formation of this tube is absolutely vital for the correct development of the baby. Now, the baby is divided into layers and these will form bones, organs, skin, eyes, and mouth.

In the middle layer, your baby’s tiny heart and circulatory system start to appear in microscopic vessels. At this point, organs such as the stomach and intestines also begin to form. In fact, the digestive system as a whole starts developing (gallbladder, liver, pancreas). Your baby does not yet have a distinct head, legs, or torso. The only visible structure is the gestational sac. However, soon it will take on a more human-like appearance.

The yolk sac² is a simpler version of the placenta. It nourishes the baby until the placenta is fully formed and ready to take its place. On ultrasound, it always appears even before the baby. It looks like a small balloon floating within the gestational sac. By the way, the gestational sac can sometimes be seen. But do not worry if it hasn’t shown up yet in an ultrasound at 4 weeks pregnant. At this stage, the baby is smaller than a grain of rice, measuring about 2 mm!

How mom is feeling

At this stage, at 4 weeks pregnant, some women already begin to feel their body is different. The hormone hCG starts being released at full speed and progesterone is released by the corpus luteum in large amounts to keep the pregnancy healthy. If the mother is not already taking vitamins to aid in the baby’s development, now is the time to start. It’s recommended to take vitamins such as Methylfolate³, the active form of folic acid, which is much more efficient.

This hormone, common in all women, is responsible for all the first symptoms. It makes the mother sensitive to smells and tastes and is the cause of nausea. In some cases, the woman does not even realize there is a new life growing inside her. But soon the symptoms will intensify and, suspecting pregnancy, she will take a urine or blood test, as I did in my 4th week of pregnancy.

Signs and symptoms

At 4 weeks pregnant, signs and symptoms are common, but the first sign is a missed period. If it is more than 5 days late, it’s ideal to check if a new life is developing. And when the positive finally comes, it’s a surprise and joy beyond words! However, some women may experience bleeding at this stage of pregnancy.

Bleeding may be due to implantation or due to low progesterone secretion. In this case, you should see a doctor as soon as possible. If you are in doubt about what is happening, it is better to get a professional opinion and detect any possible problems.

At this point, your belly may start to get firmer and your breasts may feel very sore and swollen. All this is normal in pregnancy, but it is also possible not to have any symptoms! The 4th week of pregnancy may or may not bring symptoms!

So, it is possible to have a symptom-free pregnancy. Just make sure that your hCG is rising as it should. If in doubt, get a quantitative beta hCG test to check hormone progress. Now is also the time to look for a good doctor and start prenatal care!

External factors

If the woman hasn’t started taking folic acid by now, it is very important to start as soon as possible! This vitamin has the power to prevent neural tube defects in the baby. It’s also possible the woman may notice pregnancy symptoms like nausea, dizziness, or sleepiness even before she can take a test. There may also be endometrial shedding with clots.

In this case, it is unlikely that the pregnancy will continue. This is called a chemical pregnancy or micro-abortion. If heavy bleeding is suspected, a gynecologist can advise.

Reader Questions:

What does a 4-week fetus look like?

At 4 weeks pregnant, the baby is so small it is compared to a grain of rice. It’s about 2 mm and does not yet look like the human being that is forming.

What is the uterus like at 4 weeks pregnant?

At 4 weeks pregnant there is no visible change to the uterus yet, since the embryo is still very tiny and not taking up space.

What are the symptoms of pregnancy at 4 weeks?

At 4 weeks, the main symptom is a missed period. However, many women may already experience nausea, dizziness, or even extreme nipple sensitivity. At 4 weeks pregnant you may already notice the symptoms and confirm it with a pregnancy test. A great ally for women in this phase is the anti-nausea bracelet.