13.68: Pregnancy and Childbirth

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Why is it called labor?

So…the mother carries the developing baby for nine months. We know about the tremendous growth and development of the embryo and fetus. Then comes labor.

Pregnancy and Childbirth

Pregnancy is the carrying of one or more offspring from fertilization until birth. It is the development of an embryo and fetus from the expectant mother’s point of view.

The Mother’s Role

The pregnant mother plays a critical role in the development of the embryo and fetus. She must avoid toxic substances such as alcohol, which can damage the developing offspring. She must also provide all the nutrients and other substances needed for normal growth and development. Most nutrients are needed in greater amounts by a pregnant woman, but some are especially important, including folic acid (vitamin B₉), calcium, iron, and omega-3 fatty acids.

Childbirth

Near the time of birth, the amniotic sac breaks in a gush of fluid. Often when this occurs, women say that their "water broke." Labor usually begins within a day of this event. Labor involves contractions of the muscular walls of the uterus, which cause the cervix to dilate. With the mother’s help, the contractions eventually push the fetus out of the uterus and through the vagina. Within seconds of birth, the umbilical cord is cut. Without this connection to the placenta, the baby cannot exchange gases, so carbon dioxide quickly builds up in the baby’s blood. This stimulates the brain to trigger breathing, and the newborn takes its first breath.

Baby immediately after birth

Immediately after birth.

Summary

A pregnant woman should avoid toxins and take in adequate nutrients for normal fetal growth and development.
During childbirth, contractions of the uterus push the child out of the body.

Review

What causes the fetus to be pushed out of the uterus during birth?
Why is the umbilical cord cut before a newborn has started to breathe on its own?