Week 3

Your Baby's Development
Even though you may not know you're pregnant yet, your baby continues to grow and develop. Over the past week, the fertilized egg has divided into hundreds of cells and is now called a blastocyst. The blastocyst is hollow and filled with fluid - if you could look inside your uterus now, it would barely be visible.

Around the third week (usually between days 4 and 7), the blastocyst implants itself in the endometrium, the lining of the uterus. The implantation on the uterus is an essential connection - the endometrium will provide the developing embryo with nutrients and will remove wastes. Over time, this implantation site will develop into the placenta. During pregnancy, the placenta nourishes and protects your developing baby.

Your Body
Now that it's about a week after fertilization, your body may begin to let you know that you're pregnant. The blastocyst will begin to secrete hormones that stop your body from releasing the endometrium and tissue in your uterus - so you may notice that you've missed a period.

Adequate vitamin intake, especially folic acid, protein, calcium, and iron, is essential for nourishing your baby. A folic acid supplement - which, ideally, you've been taking since before you conceived - is particularly important because folic acid helps prevent defects of the neural tube (the head, spine, and related structures), which forms very early in pregnancy.

Your intake of protein, which is used to create new tissue, should double during pregnancy - you should be eating at least 60 grams a day. In addition, calcium, at least 1,200 milligrams, is necessary for the development of bones and teeth, so make sure you're getting a good dose of dairy products, leafy green vegetables, and legumes. Iron is essential during pregnancy as you support the continual increase of your baby's blood volume. Good sources of iron include red meat, legumes, eggs, and leafy green vegetables, and you should consume at least 30 milligrams of iron daily.