Babies

Weeks 1 and 2

Baby:Your baby is still just a glimmer in your eye. Although it's confusing to think about a pregnancy starting before your child is even conceived, doctors calculate your due date from the beginning of your last cycle since it's hard to know exactly when conception occurred.

Mom-to-be: At the beginning of a cycle, about 20 eggs called ova begin to ripen and occupy fluid-filled sacs called follicles. One of these follicles matures and ruptures, releasing an egg that will travel down the fallopian tube, where it awaits fertilization. This all takes place about 14 days before the end of your cycle. This is the time you're most fertile, so light some candles, take the phone off the hook, and set aside some intimate time. An egg can be fertilized for only about 12 to 24 hours once the ovum is released. Don't be disappointed if it doesn't work the first time. You have only about a 20% chance of getting pregnant each month.

Tip for the Week: Make sure you've scheduled a preconception visit with your OB-Gyn to determine risks of genetic diseases, environmental hazards and lifestyle changes necessary to ensure a healthy pregnancy and baby. Most important, make sure you've started taking 0.4 milligrams, or 400 micrograms, of folic acid a day. Folic acid taken a few months before conception has been shown to dramatically reduce the likelihood of neural tube defects, such as spina bifida.

Week 3

Baby:Congratulations! If your egg and your partner's sperm have joined successfully, your embryo is really there, although it's very small -- about the size of the head of a pin. It doesn't look like a fetus or baby; it's just a group of about 100 cells multiplying and growing rapidly. The outer layer of cells will become the placenta, and the inner layer will become the embryo.

Mom-to-be: You won't notice any changes. It's too soon. Remember, you haven't even missed your period yet.

Tip for the Week: Home pregnancy tests are about as reliable as a urine test or...