A Guide to the Fetal Stages of Pregnancy

The fetal stages of pregnancy are an intriguing journey from conception to the birth of a new human life.

Each stage of pregnancy introduces important growth and development of the baby and its many organs, systems and body functions.

Fetal Stages of Pregnancy in the First Trimester
The first 14 weeks of pregnancy make up the first trimester. The baby's growth and development is rapid and complex during these early weeks.

First few weeks: The cells of the fertilized egg divide rapidly. The ball of cells nestles into the uterine wall lining. Cells begin to perform their specialized roles and organs begin to be formed.

Week 5: The embryo's heart begins to beat and circulate blood. Arm and leg buds begin to emerge. Brain, spinal cord and nervous system are established. Pigment is produced in the eyes, causing them to darken.

Week 6: The fetus's digestive system is forming. The liver has begun to take over production of blood cells. The brain begins to control the movement of muscles and organs.

Week 7: The embryo begins to move spontaneously. The umbilical cord joins the embryo to the placenta.

Week 8: The fetus, as it's now called, is now a little more than 1 inch long.

Month 3: The fetus can now turn its head, curl its toes and open and close its mouth. The fetus weighs an ounce or two.

Fetal Stages of Pregnancy in the Second Trimester
In the second trimester, a pregnant woman will begin to show and will start to feel the baby move and kick. Many parents want to find out what sex the baby is at this stage of pregnancy. 

Month 4: The fetus is now 8-10 inches long. The fetus's sex organs are becoming distinctly male or female.  It can hear the mother's heartbeat and voice, as well as other sounds outside the womb.

Month 5: The mother begins to feel the fetus move at this stage. The number of nerve cells increases rapidly at this stage of pregnancy. Loud noises may cause the fetus to startle and jump.

Month 6: If born now, the baby would probably survive if given proper care. Internal organs are maturing and the skin is translucent, wrinkled and covered by lanugo and vernix.

Fetal Stages of Pregnancy in the Third Trimester
In the third trimester of pregnancy, the size and weight of the baby can cause the mother to be uncomfortable and suffer some aches and pains.

Month 7: The baby's eyelids slowly open at this stage of pregnancy. His eyes begin to respond to light and eyelashes form. The baby recognizes his mother's voice. He is storing calcium and iron.

Month 8: The baby has regular periods of activity and rest at this stage. The baby's skin begins to store a layer of fat underneath for nourishment and insulation. The baby begins to settle into a favorite position. The brain and nervous system are continuing to develop. The baby's eyes are open now.  Although he doesn't actually breathe yet, he may hiccup.

Month 9: The baby weighs between 6 and 9 pounds. His hands can grasp firmly, Near the end of the month, he'll take settle into the position he'll be in for delivery, usually head down facing the mother's back.

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