Fetal Development: Week 3

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Week 3 of your Pregnancy

Fertilization and Implantation

At conception, only a single sperm fertilizes an egg. If the fertilized egg splits into 2 (or more) the result is identical twins (or triplets….). If 2 or more eggs are each fertilized by a different sperm,the result is 2 or more fraternal (non-identical) babies.

Approximately ⅓ of all twins will be identical and ⅔ non-identical.

Both the sperm and the egg contain 23 chromosomes that will combine to make up the zygote which contains a total of 46 chromosomes. The most amazing fact is that your baby’s gender, eye color, hair color, and much more has already been determined.

The fertilized egg now becomes a cluster of rapidly dividing cells, called a zygote, as it makes its way up the fallopian tube to the uterus (womb).

Pregnancy week 3

Seven days after conception, the zygote burrows itself into the plump uterine lining (endometrium) –  implantation occurs, which provides an essential connection between mother and baby and this is where the placenta will eventually develop.

The zygote has by now developed into a blastocyst. 

What to Expect

During this week it is unlikely that you will notice any changes in your body. Remember, you haven’t even missed your period yet.

Spotting or light vaginal bleeding may occur at implantation and is one of the early signs of pregnancy.

Tip for Week 3

Get advice on healthy eating during pregnancy – what to eat and what to avoid.

It is also important that you get enough calcium, iron, and folic acid.

Wondering if you are pregnant? Why not take the “Am I Pregnant?” Quiz?


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