Week 3

Carola Felchner is a freelance writer in the medical department and a certified training and nutrition advisor. She worked for various specialist magazines and online portals before becoming a freelance journalist in 2015. Before starting her internship, she studied translation and interpreting in Kempten and Munich.

More about the experts All content is checked by medical journalists.

Congratulations - at the beginning of the 3rd week of pregnancy (3rd week of pregnancy) you are "officially" pregnant. The chromosomes of the egg cell and sperm now fuse together and cell division begins: the tender beginning of a new life. Read more about it here 3rd week of pregnancy: Whether the hair and eye color of your child has already been determined and why you suddenly no longer like your favorite wine.

3rd week of pregnancy: This is how your baby is developing

The female egg does not make life easy for couples who want to become parents. After ovulation, it is only capable of fertilization for about a day. If a sperm manages to get through to the egg and fertilize it in this time window, the baby's first cell is created: the new life begins in the 3rd week of pregnancy.

The fertilized egg contains all the information about the new human child, such as eye color, hair color, height and gender. Even before it reaches the uterus on its way through the fallopian tube, it begins to divide diligently. One cell becomes two, then four, then eight ... Each of these cells has a task. One of them ultimately becomes a heart cell, another a skin cell, and so on.

After rolling around freely in the uterus for a few more days, the fertilized egg nests in the uterine cavity five to six days after conception, i.e. towards the end of the 3rd week of pregnancy. In other words, it creates a connection to the maternal bloodstream so that it can later be taken care of. With “start-up capital” of around 100 cells, the so-called blastocyst, or later embryo, is now called: grow, grow, grow.

3rd week of pregnancy ultrasound: That can be seen

Did you realize you were pregnant much later? You are not alone. Often women in the 3rd week of pregnancy do not even know that fertilization has occurred - simply because hardly anything has changed physically. And where there is no suspicion of pregnancy, there is no ultrasound. Week 3 would be much too early for this anyway. You would see nothing more than a highly built-up lining of the uterus. The blastocyst is now less than a millimeter in size and does not usually become embedded in the uterine lining until the end of the 3rd week of pregnancy.

3rd week of pregnancy: That will change for you

If a sperm has penetrated the outer egg shell and touched the inner one, the outer one becomes solid. This prevents another sperm cell from entering.

In this undisturbed tête-à-tête of egg cell and sperm, the different sets of chromosomes from you and your partner also come together - there are a total of 46 chromosomes, 23 from each parent, on which a total of around 40,000 genes are arranged. In order to know which chromosome we are talking about, scientists number these 23 pairs of chromosomes from 1 to 46. For example, numbers 45 and 46 are the chromosomes that determine your child's sex. They are better known as the X and Y chromosomes.

All genes are present twice in the 3rd week of pregnancy. It is only in the embryonic phase that it is decided whose genes the child will take over. It could be mom's blue eyes or dad's prominent cheekbones.

Of all this magic that is currently going on in your body, you will not notice anything in the 3rd week of pregnancy. "Symptoms" don't really exist at this point.

3rd week of pregnancy: That is important now

You've probably heard it a dozen times, but here again: Alcohol, nicotine, and pregnancy are incompatible. Not even “a little”. With wine, cigarettes and the like, you drastically increase the risk of miscarriage, premature birth or stillbirth. It is best to do without both stimulants while you are still in the "production phase". With the glow sticks, it is not easy to do without them from one day to the next. Then you should slowly reduce smoking. As soon as your pregnancy works out, you should be "smoke-free".

Nature often helps to live through the pregnancy in a healthy way: Many women who are 3 weeks pregnant intuitively behave correctly - especially when it comes to harmful influences. It can happen that the evening glass of wine suddenly no longer tastes good or that the cigarette smoke is perceived as unpleasant by the person sitting next to you.

Midwife tip

The 3rd week of pregnancy is still a very early point in time, but from the moment the pregnancy is established or even suspected, I advise you to completely refrain from alcohol and nicotine. Perhaps you only find out that you are pregnant when the glass of wine or cigarette no longer tastes good? Your body knows how to protect the baby, even in the 3rd week of pregnancy - listen to him!