Fetal Development

Development begins on the day of fertilization. © Life Issues Institute	Day One Sperm join with the egg to form one cell. This new cell is called a zygote. From the very first day the new life has 46 chromosomes, 23 from each parent. These chromosomes contain the complex genetic blueprint for every detail of human development. The child's sex, hair color, eye color, height, and skin tone are already present, just waiting to develop. A pregnant woman may notice her first missed menstrual period at the end of the second week after conception or about four weeks after the first day of her last normal period. There are different kinds of urine tests for pregnancy. Some may not be accurate for up to three weeks, or five weeks after the first day of your last normal period. To ask questions about conception, click here.
© Life Issues Institute	2 Weeks — Fetal Life (4 WEEKS after the first day of the last normal menstrual period) 4 weeks pregnant The human embryo is about one-hundredth (1/100) of an inch long. Implantation began the first week To find out more about the first month of pregnancy, click here.
By the 25th day, the heart begins to beat. © Life Issues Institute	4 Weeks — Fetal Life (6 WEEKS after the first day of the last normal menstrual period) 6 weeks pregnant The embryo is about one-sixth (1/6) of an inch long. By the end of the first month, the embryo has a head and a trunk. Structures that will become arms and legs, called limb buds, begin to appear. The heart, now in a tubular form, begins to beat by the 25th day. To find out more about fetal development in the first trimester, click here.
	6 Weeks — Fetal Life (8 WEEKS after the first day of the last normal menstrual period) 8 weeks pregnant The embryo is about half an inch long and has a four-chambered heart. Electrical activity begins in the developing brain and nervous system. The fingers begin to develop. The embryo has nostrils. To find out more about fetal development in the first trimester, click here.
The embryo begins to form arms, legs, hands, toes and a face. © Life Issues Institute	8 Weeks — Fetal Life (10 WEEKS after the first day of the last normal menstrual period) The embryo is about one and one-fifth (1 1/5) inches long. The head is about half the size of the embryo. The beginnings of all key body parts are present, although they are not completely developed or positioned in their final locations. The embryo has ears, fingers, and toes. To find out more about fetal development in the first trimester, click here.
The fetal heart beat can be detected electronically. © Life Issues Institute	10 Weeks — Fetal Life (12 WEEKS after the first day of the last normal menstrual period) The fetus is about two and one-half (2 1/2) inches from head to rump. The fingernails are developing. Between 8 and 10 weeks, the fetus begins small, random movements, though they are too slight to be felt yet. The fetal heartbeat can be detected electronically. To find out more about fetal development in the first trimester, click here.
The doctor can often tell you if the fetus is a boy or a girl. © Life Issues Institute	12 Weeks — Fetal Life (14 WEEKS after the first day of the last normal menstrual period) The fetus is about three and one-half (3 1/2) inches from head to rump. The fetus is able to swallow, and the kidneys are able to make urine. A doctor may be able to tell you if it is a boy or a girl by special tests. To find out more about fetal development in the second trimester, click here.
© Life Issues Institute	14 Weeks — Fetal Life (16 WEEKS after the first day of the last normal menstrual period) The fetus is about four and three-fourths (4 3/4) inches from head to rump. The head is erect and the legs are developed. To find out more about fetal development in the second trimester, click here.
The fetus can kick, swallow and sleep. © Life Issues Institute	16 Weeks — Fetal Life (18 WEEKS after the first day of the last menstrual period) The fetus is about five and one-half (5 1/2) inches from head to rump. The ears stick out from the head. To find out more about fetal development in the second trimester, click here.
Now the woman begins to feel fetal movements. © Life Issues Institute	20 Weeks — Fetal Life (22 WEEKS after the first day of the last normal menstrual period) The fetus is about seven and one-half (7 1/2) inches from head to rump. The fetus has fingerprints, and may have some head and body hair. Although the fetus has been able to move for several weeks, the pregnant woman now feels movements, known as "quickening." To find out more about fetal development in the second trimester, click here.
About 4 out of 10 babies born now will live. © Life Issues Institute	24 Weeks — Fetal Life (26 WEEKS after the first day of the last normal menstrual period) The fetus is about nine (9) inches from head to rump. The fetus can respond to sound. About 4 out of 10 babies born now will live. To find out more about fetal development in the second trimester, click here.
The fetus has lungs that can breathe air. © Life Issues Institute	28 Weeks — Fetal Life (30 WEEKS after the first day of the last normal menstrual period) The fetus is about ten and one-half (10 1/2) inches from head to rump. The fetus has lungs that are capable of breathing air, although medical help may be needed. The eyes are open. About 9 out of 10 babies born now will survive. To find out more about fetal development in the third trimester, click here.
© Life Issues Institute	32 Weeks — Fetal Life (34 WEEKS after the first day of the last normal menstrual period) The fetus is about eleven and three-fourths (11 3/4) inches from head to rump. Almost all babies born now will live. To find out more about fetal development in the third trimester, click here.
The fetus can grasp firmly.	36 Weeks — Fetal Life (38 WEEKS after the first day of the last normal menstrual period) The fetus is about thirteen and one-half (13 1/2) inches from head to rump. The fetus can grasp firmly. To find out more about fetal development in the third trimester, click here.
The baby is ready to be born.	38 Weeks — Fetal Life (40 WEEKS after the first day of the last normal menstrual period) The fetus is about fourteen (14) inches from head to rump, and may be 20 inches or more overall. The baby is full term and ready to be born. To find out more about fetal development in the third trimester, click here.