First Trimester

Your Baby - Month 1

After your egg is fertilized by your partner's sperm, it takes between 5 to 7 days for it to make its trip down your fallopian tube to your uterus. Once it arrives in your uterus, the egg attaches itself to the lining of your uterus in a process called implantation. Once implantation occurs, your baby begins to grow rapidly.

Shortly after implantation the placenta and umbilical cord begin to form, which will provide nourishment and oxygen to your baby and carry away the baby's wastes. Your baby is protected from bumps and pressure because it is enclosed in a sac of fluid, called the amniotic sac.

By the end of the 4th week, your embryo's cells have differentiated into a wide range of specialized cell types. Some will become part of a limb. Some, part of a hand. And some, will make up a lense of an eye.

By the end of the 5th week, your embryo is made up of three crucial layers: The ectoderm (the skin and nervous system), the mesoderm (muscles, bones and heart) and the endoderm (the lining of the stomach, lungs, liver and pancreas). The eyes and other features begin to form, as do tiny buds that will become your baby's arms and legs. Your baby's heart also forms, and it begins to beat on the 33rd day of pregnancy. However, it is impossible to hear the heart beating at this time.

By the sixth week, your baby looks more like a tadpole than a baby: it's head, tail and arm and leg buds are easily recognizable.

By the end of 6 weeks, your baby is about 1/4 inch in length (10,000 times larger than s/he was at conception!) and weighs a fraction of an ounce.