Congratulations on your pregnancy! In this article, you'll be able to read about everything related to your pregnancy in week 4. You'll find information about the development of the baby, how the mother's body is changing, and tips you may need along the way. When you are 4 weeks pregnant, the embryo is the size of a poppy seed!
Baby: What happens when you are 4 weeks pregnant?
Now it's up to us and our experienced midwives to guide you through the next nine months. Our goal is to be with you along the way and provide you with all the important and interesting information you need.
Fertilization and ovulation
You are now pregnant, which means that one (or more!) eggs have been fertilized. This happens when you ovulate, which usually happens 12-16 days before your next period. During ovulation, the egg is captured by the fallopian tube and upon fertilization, the man's sperm meets the woman's egg in one of the fallopian tubes. One of the sperm will enter the egg first and thus win the race.
Four days after fertilization, the egg will travel through the fallopian tube towards the uterus and around day six it will attach to the lining of the uterus. Then you are officially pregnant! At this point, the fertilized egg or embryo is called a blastocyst, and it will hatch when a hole forms in the eggshell. The blastocyst then makes its way to the uterus and embeds itself in the lining of the uterus.
Once in the endometrium, the embryo divides. One part forms the placenta and membranes, while the other part forms the embryo itself. Depending on where in the uterus the embryo attaches, the placenta will form. This means that the placenta is positioned differently in every pregnant woman. It can either attach to the top of the uterus, the front wall or the back wall. You can also have a low-growing placenta. Where your placenta is located is something you will hear more about later on during an ultrasound scan with your midwife.
The placenta and hormones
The placenta produces the hormone HCG, which stimulates the production of progesterone. You probably recognize this from taking a pregnancy test, as it is the levels of HCG that affect the test and show whether you are pregnant or not. Hence, a pregnancy test can almost never be wrong, as there is no placenta that secretes HCG if you have not been fertilized.
In the place in the ovary where your egg has been released, there is now a corpus luteum. It produces the pregnancy-preserving hormone progesterone and the ovaries produce the hormone oestrogen.
Download The Baby Journey app in the App Store or Google Play and follow your pregnancy week by week.
Mom: Now life changes!
Your body is now in full swing, creating an embryo 💜.
Perhaps you are already experiencing breast tenderness, nausea and stomach pains? The abdominal pain is similar to the pain many women feel before their period, which can make it difficult to figure out if it's actually a sign of pregnancy or if your period is coming. Fortunately, your pregnancy test has given you a definite answer and it can't actually be wrong, although it may feel like you need to do another handful of tests to be sure.
If you have no pregnancy-related symptoms at all, this is perfectly normal. How you feel during pregnancy varies enormously from woman to woman. From now on, it is a good idea to go in with the attitude of never comparing your pregnancy with anyone else's.
Weeks of pregnancy
The weeks of pregnancy start counting from the first day of your last period, even though the fertilizing intercourse has not actually taken place yet. Around day 14 after your period starts, you ovulate, and it is only then that the egg can be fertilized by a sperm and lead to a pregnancy.
Menstrual cycle and ovulation
If your menstrual cycle is 28 days, which is the average, then the pregnancy starts counting two weeks before the actual conception takes place. This means that the actual pregnancy is 38 weeks, although a pregnancy is usually referred to as 40 weeks. If your menstrual cycle is regular and you get a positive pregnancy test on the day your period stops, this means you are in week 4+0. If you're pregnant for the first time, the calculations can be a bit confusing, so let's clear it up:
In short, the number 4 means that you have completed four full weeks, and +0 means that you have completed four full weeks and zero days (i.e. exactly four weeks). When you are in 4+6, it means that four full weeks and six days have passed.
Here in the Baby Journey app, you will quickly realize that it says you are in week 5 when you are in week 4+0. Maybe it sounds confusing? So let's explain this further: When the app shows you are in week 5 (4+0), you are in the fifth week of pregnancy, but you haven't gone through five full weeks of pregnancy yet. Imagine how people talk in sports, such as football. 4 minutes have been played (four full weeks) and the 5th minute of the match is in progress (fifth week).
To make this even more tricky, health professionals usually talk about gestational weeks. This is how many weeks and days the fetus actually is. In other words, health professionals will always say that you are in the fourth week when you are 4+0 weeks pregnant, while the commonly used term is the week you are in, i.e. week five.
This can be useful to know when you go to your midwife's office, although they usually have full control and always ask when your last period started to figure out how far along you are.
The articles About ovulation, getting pregnant and how long does it really take? describes this process further.
If you need early contact with a midwife or doctor during pregnancy, you can already contact a midwifery clinic to book an early health consultation. It is also possible to get help from your health center if you need to see a doctor. If you are already healthy, you can wait a few weeks before contacting the midwife to book a first health consultation or registration consultation.
Here you can read about pregnancy in week 5.