Stages of Pregnancy
Fetal Development
Understanding what is going on inside your body is important. Here is a brief look at the stages of fetal development.
4 Weeks
When conception (fertilization) occurs, the baby's features, including sex, hair and eye color, have already been determined. On the third week, the heart begins to beat. On the fourth week, the backbone and muscles are forming. Arms, legs, eyes and ears have begun to show. There is enough of the hCG hormone (specific to pregnancy) in the mother's body to now give a positive pregnancy test, if she is pregnant.
7 Weeks
At this age, the baby's heart has been beating for one month and fingers and toes are developed. The baby begins to move spontaneously.
8 Weeks
The fingers and toes have soft nails. The mouth has 20 buds that will become "baby teeth." You can hear your baby's heartbeat for the first time (10 to 12 weeks) using a special instrument called a Doptone. For the rest of pregnancy, the body organs will mature, and the fetus will gain weight. By the end of this month, the fetus is 2 1/2 inches long and weighs a little over 1 ounce.
18 Weeks
The baby is 8-10 inches long and weights a half pound or more. Fine hair has begun to grow on the head. The fetus moves, kicks, and swallows. The skin is pink and transparent.
24 Weeks
The baby is more than 12 inches long and will react to loud noises. If the baby were born in this month and given proper care, he would survive. The fetus has developed sleeping and waking cycles and mom will begin to notice when each of these takes place. The fetus has a startle reflex and the air sacs in the lungs have begun formation. The brain is developing rapidly over the next few weeks. The nervous system has developed enough to control some functions.
