Your Pregnancy Week-by-Week - 4 Weeks Pregnant

4 Weeks Pregnant

Placenta and embryo begin forming

Although you may have just begun to wonder if you are pregnant, your soon-to-be baby has already reached her home: the blastocyst has ended its trip to your uterus from your fallopian tube. 

While there, it implants into the uterine lining creating the unbreakable bond to you that will continue for the next eight months.

As soon as the tiny ball of cells is inserted in your uterus, the great division will arise, divided into two categories. Your son or daughter will become part of what is now known as the fetus, while the other half becomes the placenta, the lifeline of your infant, which channels nutrients and holds waste before birth. 

4 weeks pregnant is how many months?

If you're 4 weeks old, so you're in the first month of pregnancy. There are just 8 months to go!

Development of the embryo and amniotic sac

Your little embryo is busy building up a home, considering its incredibly small size, not longer than 1 millimetre and not larger than a poppy seed (think about that while you eat your morning bagel).

As the amniotic sac (also called the water bag) forms around it, so does the yolk sac, which will then be inserted into the digestive tract that evolves with your infant. 

The embryo now has three different cell layers that will develop into specialised areas of the body of your infant. The inner layer will grow into the digestive tract, liver and lungs of your infant, known as the endoderm. Your baby's nucleus, reproductive organs, bones, kidneys and muscles will soon be the middle sheet, called the mesoderm. And your baby's nervous system, blood, eyes and outer layer of skin will gradually form the outer layer or ectoderm.

Your Body at Week 4

4 Weeks Pregnant blog the pod collection


No symptoms yet?

Only a week after fertilisation, so to speak, baby-making is still in its infancy. Your body is gearing up, big time, changing from a tried-and-true friend to a wild and wacky scientific experiment at 4 weeks pregnant. 

Chances are that you're ignorant of all the hubbub. Although some women endure these pesky, early pregnancy-like PMS signs, including mood changes, bloating, and cramping, some don't notice anything. 

Whatever you feel or don't feel, the pregnancy test might be too early to see a conclusive outcome.

The egg implants

And if you may not feel pregnant yet, here's what's happening behind the scenes.

This week, the fertilized egg and your uterus make contact in a procedure called implantation, when the blastocyst that you would call your baby one day starts to bind to the uterine lining. 

Implantation bleeding can occur up to 25 per cent of the time when the packet of cells burrows its way through the uterine wall. Implantation bleeding happens faster than your anticipated duration, which is typically very scant and either light yellow, light red or light blue.

For your time, don't mistake it and don't think about the blood. It's not a symptom of anything going wrong. In your belly, you might feel a little discomfort and your breasts may feel a little tender and perhaps wider. 

Pregnancy hormones will soon make an appearance

The egg begins to emit hCG, or human chorionic gonadotropin, within six to 12 days of fertilisation, the fertility hormone that will very soon turn the line on your pregnancy test pink or blue and life upside down. 

The corpus luteum (the once-follicle from which this egg was released) is alerted by HCG that it has to hang around to produce progesterone and estrogen to nourish the fetus until it takes around eight weeks for the placenta to take over.