What happens in the 3rd week of pregnancy?

In the third week of pregnancy, your body is undergoing huge changes but you may not even realize you are pregnant. Early signs and symptoms might appear as your baby is just starting its new journey towards being born.

Fertilization occurs at about the start of week 3 of pregnancy. This occurs when one of the sperm penetrates the egg and the membranes of the sperm as well as egg unite thus indicating pregnancy. At this particular point, it is impossible for other sperms to enter. The fertilized egg divides until a solid ball of cells is formed.

Next, it travels down the fallopian tube into the uterus, during a 7 to 10 day trip, where it eventually implants into the uterine lining and continues to grow and develop. This is a confirmation that you are pregnant.

Your Body

Sufficient intake of certain nutrients, like folic acid, calcium, protein, and iron, is essential for nourishing the baby. A folic acid supplement — which, ideally, you've been taking even before you conceived — is mainly important as folic acid helps prevent defects of the neural tube (structure giving rise to the brain and spinal cord), that forms very early in pregnancy.

Your protein intake, which is used to create new tissue, must increase during pregnancy. Also, calcium is essential for the development of bones and teeth, so make sure you're having a good dose of dairy products, leafy green vegetables, in addition to legumes. Iron is also essential as you support the continual increase of your baby's blood volume. Some sources of iron include red meat, eggs, legumes, and green leafy vegetables.

Your Baby's Development

Although you may not feel that you're pregnant at this point, you have a baby growing and developing inside of you! Although your baby was just conceived, remember that he or she is working overtime. The fertilized egg is going through a process of cell division.

Nearly 30 hours after fertilization, the fertilized egg divides into 2 cells, then 4cells, then 8 cells, and continues dividing as it moves from the fallopian tube to the uterus. Once it gets to the uterus, this group of cells appears like a tiny ball and is called morula.

The morula becomes hollow and gets filled with fluid — it is then known as a blastocyst. Near the end of the second week, the blastocyst attaches itself to the endometrium, the lining of the uterus. This is known as implantation.

The implantation in the uterus creates an important connection — the endometrium provides the developing embryo with essential nutrients and removes wastes. Over time, this implantation site develops into the placenta.

At the end of this week, the embryo is well fixed in the wall of your uterus. Your baby is no longer a fertilized egg; it has turned into an embryo.

The brain and the backbone start to form.

The external covering also changes and starts the process of creating the placenta and the amniotic cavity (which surrounds the placenta).

The heart is still being formed, but has already started beating!