Chapter 27 Heredity: Labor and Delivery

What is delivery?

The arrival of the newborn infant into the outside world; birth

What is an episiotomy?

a surgical cut made at the opening of the vagina during childbirth, to aid a difficult delivery and prevent rupture of tissues.

As parturition approaches, the contractions

increase in force and frequency, changing the position of the fetus and moving it toward the cervical canal.

What are the contractions like in the dilation stage?

labor contractions last up to half a minute and occur once every 10-30 minutes; their frequency increases steadily.

When does the placental stage end?

with the ejection of the placenta, or afterbirth.

How long is the placental stage?

within an hour of delivery

What are the contractions like in the expulsion stage?

Contractions reach maximum intensity, occurring at perhaps two- or three-minute intervals and lasting a full minute.

Late in this dilation stage, what happens to the amniochorionic membrane?

It ruptures, an event sometimes referred to as "having one's water break."

What happens during the placental stage?

Muscle tension builds in the walls of the partially empty uterus, which gradually decreases in size (STAGE 3). This uterine contraction tears the connections between the endometrium and the placenta.

What does the dilation stage begin with?

The onset of true labor, as the cervix dilates and the fetus begins to shift toward the cervical canal (STAGE 1), moved by gravity and uterine contractions

How long is the dilation stage?

This stage is highly variable in length but typically lasts eight or more hours.

When does expulsion end?

When the fetus has emerged from the vagina?

What are the three stages of labor?

dilation, expulsion, placental

How long is the expulsion stage?

less than 2 hours

During true labor, where does each contraction begin?

near the top of the uterus and sweeps in a wave toward the cervix

What is a cesarean section?

surgical delivery of a baby by making an incision through the abdomen and into the uterus

What does the expulsion stage begin with?

the cervix, pushed open by the approaching fetus, completes its dilation (STAGE 2).

What is parturition?

the forcible expulsion of the fetus