From Celebrate Life Ministry.
Fertilization - The sperm joins with the ovum to form one cell. This one cell contains the complex genetic makeup for every detail of human development – the child’s sex, hair and eye colour, height, skin tone, etc.
Month One - The first cell divides and cell division continues in an orderly fashion as the small group of cells travels down the Fallopian tube to the uterus. There are over 100 cells present when this tiny embryo reaches the uterus 7 to 10 days after fertilization. Foundation of the brain, spinal cord and nervous system are already established, and on day 21 the heart begins to beat in a regular fashion. Muscles are forming, and arms, legs, eyes and ears have begun to show. The embryo is 10,000 times larger than the original fertilized egg and developing rapidly.
Month Two - The pre-born baby has all her fingers. Brain waves can be detected and the brain is controlling 40 sets of muscles as well as the organs. The jaw forms, including teeth buds in the gums. The eyelids seal during this time to protect the baby’s developing light sensitive eyes, the stomach produces digestive juices, and the kidneys have begun to function. The developing baby is now referred to as the foetus, a Latin word meaning “Young one.”
Month Three - Unique fingerprints are evident and never change. The baby now sleeps, awakens, and exercises her muscles by turning her head, curling her toes, and opening and closing her mouth-often sucking her thumb. She breathes amniotic fluid to help develop her respiratory system. By the end of the month all the organs and systems of her body are functioning. The only major activity from now until birth is growth.
Month Four - By the end of this month the baby is 8 to 10 inches in length and weighs 1/2 pound. Her ears are functioning and the baby hears her mother’s heartbeat, as well as external noises. Because the pre-born child is now larger, the mother usually begins to feel her baby’s movements.
Month Five - Half the pregnancy has now passed. The baby is about 12 inches long. If a sound is especially loud and startling, she may jump in reaction to it. Babies born at this stage of development are surviving at an ever increasing rate, thanks to medical advances.
Month Six - Oil and sweat glands are functioning. The baby’s delicate skin is protected in the amniotic sac by a special ointment “vernix.”
Month Seven - The baby’s brain has as many cells as it will have at birth. The pre-born child uses the four senses of vision, hearing, taste, and touch. Research has documented that she can now recognize her mother’s voice.
Month Eight - The skin begins to thicken, with a layer of fat stored underneath for insulation and nourishment. The baby swallows a gallon of amniotic fluid per day. She often hiccups. She has been urinating for several months.
Month Nine - Towards the end of this month, the baby is ready for birth. After birth new brain cells are being formed for nine months. Likewise, other organ systems are still maturing. Of the 45 generations of cell divisions before adulthood, 41 have taken place in the womb. Only four more will come before adolescence. In developmental terms we spend 90% of our lives in the womb.