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This site is designed to support and expand the Hillendale Health Curriculum.

Learning about how your body grows and develops and how to take care of your body is an important part of Hillendale Health class. The following information deals with the changes that occur to a baby as it grows and develops inside of the mother's body. Find information by reading the information below or click on the contents button to look for answers to specific questions.

Being Born

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Baby Growth and Birth

Is it true that babies actually live underwater while they develop inside of their mother ?

Can you believe that you were under water for months and still were able to get oxygen. Babies grow and develop in a watery world inside of a thin sac. This sac is called the amniotic sac. The amniotic sac like the umbilical cord is also attached to the placenta. (SEE PICTURE) You didn't need to breathe air. Your mom breathed for you. When your mother breathed the oxygen would travel through her body carried by the red blood cells and would be transported to the uterus through the placenta into the umbilical cord and then into your body. Pretty AMAZING isn't it!

amniotic sac

umbilical cord


fallopian tube


How long does it take for a baby to grow and develop inside of mom?

Most babies spend about nine months growing and developing inside of their mom's womb. During the first two months the baby is known as an embryo (1 month embryo - 2 month embryo). At three months the baby has grown to at a length of three inches and a weight of one ounce. At the end of three months you will notice the beginnings of arms, legs, fingers and toes. At this stage doctors could see the baby moving and a doctor would be calling it a fetus. After six months of growing inside of mom the baby is about a foot long and weighs almost 1.5 pounds. Doctors can hear a heartbeat. Eyebrows, fingernails and footprints are developing. The mother can feel the baby moving inside of her. At nine months the average baby is between 18-20 inches long and weighs about 7-9 pounds. At this stage the baby should be fully developed and ready to be born. (8 Month Fetus)

How is a baby born?

After about nine months growing and developing inside of mom the muscles of the uterus will begin to tighten and slowly start to squeeze the baby. These movements of the uterus are known as contractions. During these squeezing motions the amniotic sac will break and the water will drain out through the mother's vagina. This is what it means when a pregnant women's "water breaks". As the contractions continue to get stronger the opening of the uterus called the cervix will get bigger and bigger until the top of the babies head can press through into her vagina. The contractions continue to get stronger and the soft walls of the vagina spread apart. Finally the head slips out and then shoulders, chest and the rest of the body. The baby can breathe, open it's eyes and hear it's mother's voice. The baby is still attached to the umbilical cord and placenta. Someone cuts the cord. The bit of cord which is still left on a babies abdomen drops off after about a week. This is where your belly button is. (Birth Process)

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Puberty | Contents | Glossary | Phys Ed | Health | Site Map | Index | Being Born

Male Reproductive System | Female Reproductive System | Review