The fourth week of pregnancy

The fourth week of pregnancy or the second week after the conception


By now you’ve probably learnt that you’re pregnant. Your body have sent you sufficient signals, the pregnancy test has confirmed your hunches and you’ve most likely found a doctor to attend and manage your pregnancy. However, if finding an obstetrician seems quite a problem, we’re welcome pay us a visit to our clinic in the heart of London to have your first prenatal checkup done.

Also, if you haven’t started yet, it’s time to take the prenatal vitamins because the following five weeks are also critical for the development of your future child. Your body is working hard to take care of the new human being developing inside you and therefore, it’s important to drink enough fluids (at least 2l/day); choose water or nutritious drinks, such as skim milk, low-fat milk, 100% fruit juices instead of sodas and coffee.

As you’ve probably found out, during the early stages of pregnancy, and especially during the fourth week, the hCG levels rise drastically. This change of your hormonal balance may cause headaches, faintness, dizziness, flatulence and nausea, especially in the morning, so be prepared and hang in there! Breath mints are sometimes helpful after these unpleasant episodes.

We’re pretty sure that you’ve already started to browse the internet for finding answers to all your questions and it’s almost certainly that you’ve often heard new terms such as the gestational age and fetal age. But…what exactly do these new terms mean?

Gestational age (also known as the LMP – last menstrual period) refers to the length of time since the first day of your last period. So, when the doctor says your gestational age is four weeks, it just means that it’s been four weeks since your last period started.

Fetal age refers to the age of your developing baby, counting from the estimated date of conception. The fetal age is usually two weeks less than the gestational age. Therefore, a four weeks pregnancy means a fetal age of the unborn baby of only two weeks.

Let’s go deeper and find out what’s happening inside you. Don’t be afraid of this technical data! No bigger than a poppy seed, the fertilized egg that will develop into your baby has ended its miraculous journey from your fallopian tube to the uterus. Once conveniently settled in its new home for the following nine months, it undergoes its first major division – the splitting into two groups of cells. The inner group of cells, reaching by now 1-2cm in length and known at this stage as the embryo, will become your baby. The outer group starts forming the placenta, your baby’s lifeline until delivery.  Until the tenth week of pregnancy, the multilayered embryo will grow into specialized parts of your baby’s body: the inner layer will develop into your baby’s digestive system, liver and lungs; the middle layer, will soon be your baby’s heart, sex organs, bones, kidneys and muscles and the outer layer, will eventually form your baby’s nervous system, hair, skin and eyes. Even though, the organs are not completely functional until birth.

In the first trimester and particularly during this period, your future baby is highly vulnerable since it undergoes the critical development stage. Consequently, it is essential to begin your “eating-well and healthy” campaign and to consider a few lifestyle changes. Making positive choices to give up some much loved vices will assist your body to nurture your new baby, as well as minimise the chances of them developing birth defects and/or being unwell after the birth. Bear in mind that smoking, alcohol consumption and medications, either on prescription or over-the-counter, are not recommended! Therefore, the future mum must switch over to healthier lifestyle with good dietary intake, regular exercise and adequate rest along with peaceful sleep.

Right now, the placenta is still forming and therefore it cannot completely discharge all its functions. However, it has already developed two layers and its main role is to provide the nutritive and the respiratory support for your future baby, by means of the umbilical cord, and to protect the baby against numerous harmful factors. The amniotic sac (which fosters the embryo) has formed as have the amniotic fluid and the yolk sac (or the yolk duct). The yolk sac produces the red blood cell and also helps to provide the nutrients to the baby until the placenta will have fully developed and took over this function.


As a future mum, you’ll pay a special attention to your pregnancy. We all know that the happiness of a mum is enormous! Well, it’s time to actually feel it and the changes have begun are natural.

Bear in mind that every pregnancy has its own particularities, so don’t worry if some of the moments we presented in this blog are not actually applying to you! Our information is strictly informative and tries to give you a general picture on the development of your future baby.