Congratulations! One lucky sperm and your egg have come together in your fallopian tube! This fertilized ovum is now called a zygote and will migrate down through your fallopian tube to your uterus. As it travels, it will undergo several rapid mitotic divisions reaching the side of approximately 120 cells.

At this point, the embryo is now called a blastocyst. A blastocyst is made up of two cell types. It has an inner cell mass, or the embryoblast, which will form the embryo, and an outer cell mass called the trophoblast, which forms the placenta. (Over the next 9 months, the placenta will feed and nourish your baby, while also disposing of its waste.) After reaching your uterus, the blastocyst will attach to the blood-rich tissue called the edometrium through a process called implantation.

Your body

Your body is just beginning to undergo the first of many, many changes over much of the next year and one of those is the production of the hormone hCG (human chorionic gonadotropin). This hormone plays an important role in supporting your pregnancy, it not only stops more eggs from being released from your ovaries but it also stops your period, keeping both your uterine lining and your blastocyst inside you!

HCG is also the hormone that is detected by pregnancy tests. It can be detected in both blood and urine. At this point you may be able to take a home pregnancy test to confirm that you are pregnant. However, the levels of hCG vary and may not show up right away, so it is a good idea to take another test a few days later to double check in case the first test comes back negative. In fact, waiting until week 4 or even week 5 may be your best bet in detecting pregnancy with a home test.

Either way, you should be conscious of what you are putting in your body. Avoid smoking, alcohol, caffeine and make sure that you are getting enough vitamins and nutrients. You are now doing the eating for two! It is important to remember that what goes into your body will be going to your baby as well and that little one needs lots of protein, calcium, and iron, in addition to other important vitamins.

Early signs of pregnancy

As early as week 3 you may begin to feel that your breasts are sore or swollen. Some women notice a small amount of spotting or vaginal bleeding called implantation bleeding. This occurs when the fertilized egg attaches to the lining of the uterus. This bleeding is earlier, spottier and lighter in color than your regular period and it doesn’t last that long. You may also begin to notice that you are more tired than usual, you may have headaches and you may even feel dizzy or lightheaded.