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Conception
A sperm cell penetrates an egg, fertilizing it. Within about three days after conception, the fertilized egg, which is dividing rapidly into many cells, passes through the fallopian tube into the uterus, where it attaches to the uterine wall. The placenta begins to form. -
Week 3
The backbone spinal column and nervous system are forming. The liver, kidneys and intestines also begin to take shape. -
Week 4
Structures that will eventually form the face and neck are becoming evident. The heart and blood vessels continue to develop and some organs are starting to develop. A home pregnancy test is now positive. By the end of week four the child is ten thousand times larger than the fertilized egg. -
Week 8
The baby is now a little over half an inch in size. Every organ is in place. Eyelids and ears are forming, and the tip of the nose is visible. The arms and legs are well formed. The fingers and toes grow longer. The baby can begin to hear. -
Week 12
The fetus measures about 2 inches and starts to make its own movements, it can now exercise its muscles, turning its head, curling its toes, and opening and closing its mouth. The sex organs of the baby should start to become clear. The baby has all of the parts necessary to experience pain. Vocal cords are complete. The baby can suck its thumb. -
Week 16
The fetus now measures about 4.3 to 4.6 inches and weighs about 3.5 ounces. The baby's eyes can blink and the heart and blood vessels are fully formed. The baby's fingers and toes should have fingerprints. Bone Marrow is beginning to form. The heart is pumping 25 quarts of blood a day. The mother will probably start to show. The ears are functioning and the baby can hear the mother’s voice and heartbeat, as well as external noises. -
Week 20
The baby weighs about 10 ounces and is a little over 6 inches long. The baby can suck its thumb, yawn and stretch. The mother has begun to feel movement. -
Week 24
The fetus weighs about 1.4 pounds now. It responds to sounds by moving or increasing its pulse. Jerking motions might be noticed if the baby hiccups. With the inner ear fully developed, it may be able to sense being upside down in the womb. Oil and sweat glands are functioning. If the baby were born and given proper care, it would survive. -
Week 28
The fetus changes position frequently at this point in pregnancy. There's a good chance of survival if the baby is born prematurely. The baby now uses the four senses of vision, hearing, taste, and touch. It can recognize it’s mother’s voice. -
Week 32
The baby's skin has fewer wrinkles as a layer of fat starts to form under the skin for insulation and nourishment. It will gain up to half its birth weight between now and delivery. Antibodies are increasingly building. -
Week 36
Toward the end of this month, the baby is ready to be born. On average, the baby is about 18.5 inches and weighs close to 6 pounds. Lungs are nearly fully developed. The head is usually positioned down into the pelvis by now. The brain has been developing rapidly.
