Fetal Development

The following is a month-by-month account of a baby's growth in the uterus. Click here if you would like to see an interactive view from the womb.

Fertilization

At the moment the nuclei of the father's sperm and mother's egg unite, a new and unrepeatable human being comes into the world. The baby has his or her own DNA, the sex is determined, and the baby attaches to the lining of the mother's womb.

Month 1

During this first month, the baby grows to 10,000 times the size at conception. By the third week, the baby's tiny heart begins to beat.

Month 2

The fetus is making rapid progress developing all her external and internal organs, baby teeth, fingers and toes, ears, nose, lips and tongue. Brain waves can be recorded. The skeleton changes from cartilage to bone. The central nervous system is now functioning, and so forty muscle sets begin their first exercises. By 8 weeks, all body systems are present, and this little one can now suck her thumb.

Month 3

The baby can now squint, swallow and move his tongue. He sleeps and awakens. Fingernails and toenails form and he now has his own unique set of fingerprints. Sensitive to touch, he will tightly grasp an object placed in the palm of his hand. He breathes amniotic fluid to help develop and strengthen his respiratory system, but he gets the oxygen he needs through the umbilical cord.

Month 4

The baby's brain has begun maturing, her taste buds are now working, and fine hair begins to grow on her head, eyebrows and eyelashes. Facial expressions similar to the baby's parents can now be seen. This month, REM's (rapid eye movements) have been recorded - a sign of dreaming.

Month 5

This month marks the half-way point to birth, and the baby is very active. Sleep habits develop and his mother can feel him move and stretch, particularly when she is resting. He is big and strong enough to kick hard against the outside of the uterine wall and dent it. Babies born at this age have survived.

Month 6

The baby's oil and sweat glands are functioning: these help regulate body temperature. She can now respond to sound. Her lungs are fairly well developed and she would stand a good chance of survival if born at this time.

Month 7

Beginning this month, the baby uses all four senses. His eyelids open and close, and the eyes look around. The baby can hear, taste, touch, cough, yawn, and hiccup. He now recognizes his mother's voice. His grip is even stronger now than it will be after his birth. The hair on his head is growing longer and the downy covering on the rest of his body is disappearing. During this time, the baby will receive antibodies from his mother providing him immunity to a wide variety of diseases.

Month 8 and 9

In the last two months, the baby continues to gain weight. She is developing a layer of fat that will keep her warm after she is born. In the 9th month, she will shift to a head-down position, preparing for birth. Her lungs are now fully developed and capable of making the transition to breathing air. After birth she will continue the human growth process for many years to come.

Resource: Little One Publishing, LLC