A patient wakes at 3 a.m. with light cramping pains every 25 minutes.

At 7 a.m. she notes a clear gush of fluid and calls her provider.

She arrives at the hospital at 8:30 a.m. and a vaginal exam shows she is 5 cm dilated and 100% effaced.

She continues to labor and at 2 p.m. has an overwhelming need to push.

She delivers a healthy boy at 3:30 p.m., and the placenta at 3:45 p.m. How long was the first stage of labor?

Choice A rationale

General anesthesia, particularly with halogenated inhalational agents, can cause uterine atony. These agents act as uterine smooth muscle relaxants, which can prevent the uterus from contracting effectively after birth. A relaxed, or atonic, uterus is the most common cause of postpartum hemorrhage because it cannot compress the blood vessels at the placental site, leading to uncontrolled bleeding.

Choice B rationale

A pudendal block provides anesthesia to the perineum, vulva, and lower vagina by injecting an anesthetic into the pudendal nerves near the ischial spines. It does not affect the uterine muscle or its contractility. Therefore, a pudendal block would not contribute to uterine atony or increase the risk of postpartum hemorrhage from a relaxed uterus.

Choice C rationale

An epidural provides regional anesthesia by blocking nerve impulses in the lower spinal segments. While high concentrations of anesthetic agents can have a mild effect on uterine contractility, modern low-dose epidurals typically do not significantly impair uterine muscle tone. The risk of postpartum hemorrhage from uterine atony is not as high with epidural anesthesia as it is with general anesthesia.

Choice D rationale

Local anesthesia, such as a perineal infiltration for an episiotomy or repair, involves injecting an anesthetic directly into the tissues of the perineum. This localized effect does not circulate systemically in a way that would relax the uterine smooth muscle. Therefore, local anesthesia would not contribute to a relaxed uterus or postpartum hemorrhage.

Choice A rationale

Uterine contractions are governed by complex hormonal and mechanical pathways involving oxytocin and prostaglandins. Walking and position changes primarily influence fetal positioning and maternal comfort, not the frequency or duration of contractions. In fact, these activities can sometimes strengthen contractions by utilizing gravity to increase pressure on the cervix.

Choice B rationale

The primary goal of walking and frequent position changes is to reduce pain and increase comfort. By changing positions, the mother can alleviate pressure on specific areas, optimize blood flow, and distract herself from the pain, which scientifically reduces the perception of pain and increases the body's natural endorphin release.

Choice C rationale

Frequent changes in position and ambulation during labor can increase comfort by reducing pressure on the sacrum and perineum, improving blood flow, and allowing the mother to find a more tolerable position. This scientifically reduces pain perception and enhances the mother's coping mechanisms, making the labor process more manageable.

Choice D rationale

Walking and position changes utilize gravity to help the fetus descend into the pelvis and rotate into an optimal position for birth. This can improve the fit of the fetal head in the maternal pelvis, promoting efficient labor progression and helping the fetus navigate the curves of the birth canal more effectively.