First Trimester--1 to 14 weeks

The first trimester is a time of explosive growth for your baby and many changes for you. Find out about your baby this trimester and take a look at some common questions and concerns. There are standard tests performed this trimester that you may want to take a look at.

Take care of yourself, eat well, and get plenty of rest. Remember that your body is working very hard, putting a lot of resources into growing a baby.

Your baby this trimester

The first trimester is a time of explosive growth for the baby. During the first two weeks, you have your period and the lining of your uterus--the endometrium--thickens to prepare for implantation of a fertilized egg.

Around the third week ovulation occurs and an egg is (hopefully) fertilized by sperm. The fertilized egg implants itself into the lining of the uterus. The egg then splits into two parts. One part will become the placenta, the other the fetus.

During the next six weeks, from week 4 through 10, the baby's eyes start to develop, the heart begins to beat, and everything a baby needs to be a baby--arms, hands, feet, nerves, muscles, skin, teeth, etc.--are formed.

At week 10, an amniotic sac filled with amniotic fluid has formed around the fetus and all the major organs are formed. The baby's face continues to form and at week 12 blood starts to circulate through the umbilical cord, carrying all the oxygen and nutrients the developing baby needs.

By week 14, the baby's lungs are fully functional and she practices breathing amniotic fluid. At this point the fetus weighs about 2 ounces and is roughly 3 1/2 inches long.

For an interesting look at the developing fetus during this time, check out The Visible Embryo.

Some resources you might find helpful: