Parturition and lactation review

Childbirth (parturition), oxytocin, and lactation.

This article briefly reviews the processes of childbirth (parturition) and lactation.

Key terms

Term	Meaning
parturition	childbirth, or delivery of fetus from the womb
lactation	production of milk by mammary glands
oxytocin	hormone that induces uterine contractions

What is parturition?

Babies sometimes mysteriously show up overnight in cartoons or movies, often dropped off by a (remarkably strong) stork. How does pregnancy actually result in the arrival of a child?

Parturition, or childbirth, is the process by which the uterus expels the fetus from the mother's body. You might have heard terms like 'water breaking', or 'dilation' (especially if you like watching medical dramas). Briefly, these are the steps involved in parturition :

the amniotic sac surrounding the baby ruptures (water breaking), signalling onset of labor.
the cervix dilates, or expands, to allow the baby to move down and out of the uterus.
the fetus and placenta are thought to send chemical signals to the maternal pituitary, which releases oxytocin to induce uterine contractions.

This reflex, also known as the Ferguson reflex, leads to quick childbirth that does not require active pushing by the mother. You might have seen this term used to describe all childbirth in your textbook. While the fetal rejection reflex does occur commonly in several species of mammals, it is not always seen in humans. Some scientists think that the Ferguson reflex only happens when the mother is very relaxed.

stronger contractions of the uterus trigger further release of oxytocin, and so on, until the force of the contractions expels the baby (and shortly after, the placenta) from the birth canal.

Let's play doctor.

hospital tales #1

One of your patients is

2

weeks past her due date, and yet to experience contractions. You decide to induce labor to deliver the baby.

Which of the following methods would you apply to induce labor in the pregnant woman?

hospital tales #2

One of your patients suffers from placental abruption, during which the placenta detaches from the uterine wall prematurely.

What would happen to the placenta under normal childbirth circumstances?

Lactation

During later stages of pregnancy, the mother's mammary glands undergo hormonal and physiological changes that induce production of milk, or lactation.

Breastfeeding allows the mother to pass on antibodies to the newborn through colostrum, or the milk produced immediately after delivery.

You have one last patient to see before you're done for the day!

hospital tales #3

A new mother is unsure about whether she wants to breastfeed her baby.

Which of the following statements can you tell her about the advantages of breastfeeding?

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