Pregnancy Week by Week – Week 3

The beginnings of the embryo

Conception has occurred! The journey of traveling down the fallopian tube to the uterus has begun. The two-celled structure rapidly divides into an embryo.

Week three begins the fascinating journey of the tiny beginnings of your baby as cells rapidly divide and the bundle of cells travels down toward its ultimate destination for the duration of your pregnancy. What else is going on? Let’s find out.

What is happening with your Baby?

Immediately after conception, the sperm and egg begin to quickly change into a fertilized ovum, called a blastocyst. The sperm and egg each brought 23 chromosomes to total 46 in the new solid ball of cells.

At week three, the little bundle of growing cells is now called an embryo. This stage of 3-8 weeks begins what is called the embryonic stage and your baby’s development is very susceptible to major problems if exposed to any harmful substances.

The embryo begins its way down through the fallopian tubes toward your uterus; a journey that takes about 3-4 days to complete. Initially, the embryo floats freely in your uterus. A small cavity begins to separate it into two parts – one will become the embryo (embryoblast) and the other becomes your baby’s placenta (trophoblast).

About 6-10 days after conception, the trophoblast releases an enzyme that allows it to attach to the lining of your uterus. By day 17 of pregnancy, the mother – placenta – baby connection is established and functioning.

During the third week, the embryo is now separating into three distinct layers called germ layers. They are the upper layer or ectoderm (which becomes skin, hair and nervous system), middle layer or mesoderm (which becomes bones, teeth, cardiovasculuar system, urogenital system) and the lower layer or endoderm (which becomes the digestive tract, liver, pancreas, bladder and vagina.)

At the end of week three, a developing heart is beating and circulating blood throughout the embryo.

What is happening to You?

You might experience a bit of bleeding when the little embryo implants itself into the wall of your uterus. This often occurs right around the time you would expect to get a period, which is one reason why women can miss the signs of early pregnancy.

Only about 8-10 days after conception, levels of hCG can be detected in your blood. hCG is produced by your baby’s placenta and is used to confirm your pregnancy.

It is so important to begin healthy eating habits as soon as you are trying to conceive. In fact, did you know that good nutrition can affect your baby’s long-term health as an adult and even the health of your grandchildren? Find out more here.

To Do List:

Begin or continue taking prenatal vitamins.

Take a pregnancy test (blood test) to confirm your pregnancy.

Eat a healthy diet.

Avoid any substances that can affect the development of the baby (See the series on smoking, OTC medications, alcohol, caffeine, etc..)