Chronology of a New Life

The life of a baby begins, of course, long before birth. Every new and unique human being begins his or her life at the moment of fertilization and, if not interrupted, will someday grow into an adult man or woman. Following are some facts of our earliest days of life, recognized in medical texts as well as basic biology books.

First Month

The sperm joins the ovum (egg) to form one cell. This one cell contains the complex genetic blueprint for every detail of human development - sex, hair and eye color, height, skin tone, etc. Over the next week the tiny fertilized egg (or blastocyst) travels down the fallopian tube into the uterus, implanting in the nutrient-rich lining which has been prepared by the hormone progesterone. The embryo begins developing very rapidly, and by 22 days the heart begins to beat. By the end of the third week the backbone, spinal column and nervous system are developing. Kidneys, the liver and the digestive tract are already taking shape. By the end of the first month the embryo is ten thousand times larger than at the blastocyst stage. This tiny baby has grown to about 1/4 of an inch in length.

Second Month

At this stage of development the head of the embryo is almost one half of his or her total size. Brain tissues grow rapidly, dividing and becoming a miniature brain that is distinctly human. By 40 days (the sixth week) brain waves can be recorded. Fingers and feet are beginning to develop. Milk teeth form at 61/2 weeks. Facial features, including ears, nose, lips and tongue, form with clarity during this month. Eyes form and darken when pigment is produced around day 35. Eyelids cover the eyes and will soon form a protective seal, reopening during the seventh month. Near the end of the month the skeleton changes from cartilage to bone. Forty muscle sets begin their first exercises and, working with the nervous system, respond with small movements to touch. The baby's blood type is often different from his or her mother's. By eight weeks all body systems are present, and from now on changes will be primarily in size and refinement of body parts already formed. The tiny baby at this stage is called a fetus, Latin for "offspring" or "young one."

Third Month

During this month the baby grows to a length of more than two inches and a weight of one ounce. At nine weeks fingerprints are evident and never change. The baby now sleeps, awakens and exercises muscles energetically - turning the head, curling toes and opening and closing his or her mouth. The palm, when stroked, will make a tight fist. Fingernails and toenails form, and the baby's sex is now identifiable. The baby breathes amniotic fluid to help develop and strengthen the respiratory system. Vocal cords are complete, and at times it appears as if this little baby is crying.

Fourth Month

Rapid growth during this month - the baby grows to eight to ten inches in length and weighs a half pound or more - means the mother often begins to show and may feel her baby move. Bone marrow is forming, and the heart can be plainly heard as it pumps up to 25 quarts of blood each day. Nutrients in food consumed by the mother are passed on to her baby within an hour or two via placenta and umbilical cord - which is transporting three hundred quarts of fluid per day! Facial expressions similar to the baby's parents can be identified at this time. Fine hair begins growing on the head, eyebrows and eyelashes. The baby learns to grip and suck his or her thumb.

Fifth Month

Half the pregnancy has now passed and this little baby is very active! Sleeping habits develop and the mother often feels her baby move and stretch, particularly when she is resting. Interestingly, babies at this stage have responded to sounds in frequencies too high and low for adults to hear. By the end of this month the baby is about 12 inches long and weighs about one pound. Babies born at this stage of development have survived.

Sixth Month

The baby, now up to 14 inches long and a pound and a half in weight, can now roll over inside the womb. Oil and sweat glands are functioning and the baby is covered by a white filmy layer called vernis (Latin for "varnish") which protects the delicate skin from the surrounding amniotic fluid. At the end of this month the baby has completed two-thirds of his or her stay in the womb and because the lungs are fairly well-developed would stand a good chance of survival if born at this time.

Seventh Month

The baby weighs at least two pounds by the seventh month. All four senses are now used, the eyelids open and close, and eyes look around. The baby can taste, touch and recognize his or her mother's voice. Eye teeth are present within the baby's gums, and this little baby's hands develop an even stronger grip. During the last trimester the baby receives antibodies from the mother through the placenta that will provide immunity to a wide variety of diseases.

Eighth Month

The skin begins to thicken with a layer of fat stored beneath for insulation and nourishment. Antibodies to give immunity against disease are continuing to be received from the mother, strengthening and preparing this baby for life outside the womb. The baby absorbs a gallon of amniotic fluid per day; the fluid is completely replaced every three hours. During this month the baby gains at least two pounds, doubling his or her weight, and the mother is probably looking forward to the delivery date!

Ninth Month

By the ninth month, weighing six to nine pounds, this baby can only turn from side to side because of very cramped quarters. At this point most babies settle into a head-down position to prepare themselves for delivery. About a week before birth, growth stops and changes in the mother's hormonal balance signal the onset of labor and birth. Over the past nine months, one cell has become two hundred million cells, weighing six billion times more than at fertilization, yet containing - in a bit greater detail - the same unique person that came into being at that first moment!

Details provided in this chronology are taken from The First Nine Months of Life by Geraldine L. Flanagan and When You Were Formed in Secret by Gary Bergel.