If you haven’t already, go ahead and schedule that first prenatal appointment. While you’re on the phone, ask for a prenatal vitamin recommendation, and find out whether the medications you’re currently taking are safe for your baby.
Start taking your prenatal vitamins, if you haven’t already, and continue to avoid drugs, alcohol and excessive caffeine. About 150 mg of caffeine per day is the safe limit according to the American Pregnancy Association, if any. You’ll want to stay away from all three during your pregnancy.
Your Body at 3 Weeks Pregnant
Your dominant follicle releases an egg, which is taken up by one of your fallopian tubes. After a few days within the tube, a sperm will fertilize this egg, and it will become an embryo: your baby’s beginning!
Now, your embryo will travel down the tube towards your uterus. As it travels, it will grow larger and the cells will start dividing from one cell to around 64 cells or more by the time the embryo reaches the uterus. Your embryo may take five days to reach the uterus. If you have significant pelvic pain at this time, inform your health care provider immediately. She’ll want to rule out the possibility of an ectopic pregnancy (one that occurs outside the uterus).
Your Baby at 3 Weeks Pregnant
At the beginning of this week, your brain releases a hormone called Luteinizing Hormone (LH) that will reach the ovary via the blood stream. This hormone makes the follicle pop open and release its egg. The egg will then travel into one of your fallopian tubes for fertilization by a sperm carrying an X or Y chromosome. X, it’s a girl; Y, it’s a boy. The sperm fertilizes the egg by entering it and allowing for its nucleus, where the DNA is, to mix with the nucleus of the egg. After the sperm enters the egg, the surface of the egg undergoes a dramatic transformation in order to prevent other sperm from entering. The egg is now an embryo.
The embryo is the very first beginning of your baby. The embryo is now starting to rapidly divide as it slowly goes down your fallopian tube to reach the main “room” of your uterus known as the uterine cavity. When your embryo reaches the uterine cavity, it might tumble around for a day or two before sticking permanently to one spot on the cavity wall. As it sticks to the uterus it will form special roots called villi. These villi find blood vessels within the uterine wall and form connections with them, allowing for nutrients and oxygen to pass from your blood stream to your developing embryo.
The early part of the baby’s placenta will start producing the pregnancy hormone Human Chorionic Gonadotropin (HCG). Some of this hormone will go to your blood and urine, and it is by detecting this hormone in your urine or blood, that you can tell if you’re pregnant or not. If you take more than one HCG blood test, your HCG level should double every two days or so in a healthy pregnancy.
The preceding information was adapted from The Pregnancy Companion.