Routinely use ultrasound to accurately establish gestational age
First trimester ultrasound should be offered to all pregnant women because it is a more accurate assessment of gestational age and will result in fewer pregnancies that are thought to be at or beyond 41 weeks’ gestation.5 In a meta-analysis of 8 studies, including 25,516 women, early ultrasonography reduced the rate of intervention for postterm pregnancy by 42% (31/1,000 to 18/1,000 pregnant women).6
Membrane sweeping (or stripping)
Membrane sweeping, which causes the release of prostaglandins, has been reported to reduce the risk of late-term and postterm induction of labor.7,8 In the most recent Cochrane review on the topic, sweeping membranes reduced the rate of induction of labor at 41 weeks by 41% and at 42 weeks by 72%.7 To avoid one induction of labor for late-term or postterm pregnancy, sweeping of membranes would need to be performed on 8 women. In a recent meta-analysis, membrane sweeping reduced the rate of induction of labor for postmaturity by 48%.9
Membrane sweeping is associated with pain and an increased rate of vaginal bleeding.10 It does not increase the rate of maternal or neonatal infection, however. It also does not reduce the CD rate. In the United Kingdom, the National Institute for Health and Clinical Excellence recommends that all clinicians have a discussion of membrane sweeping with their patients at 38 weeks’ gestation and offer membrane stripping at 40 weeks to increase the rate of timely spontaneous labor and to avoid the risks of prolonged pregnancy.11 Of note, in one randomized study of women planning a trial of labor after CD, membrane sweeping did not impact the duration of pregnancy, onset of spontaneous labor, or the CD rate.12
Steps from an expert. A skillfull midwife practicing in the United Kingdom provides the following guidance on how to perform membrane sweeping.13
- Prepare the patient. Explain the procedure, have the patient empty her bladder, and encourage relaxed breathing if the vaginal examination causes pain.
- Abdominal exam. Assess uterine size, fetal lie and presentation, and fetal heart tones.
- Vaginal exam. Ascertain cervical dilation, effacement, and position. If the cervix is closed a sweep may not be possible. In this case, massaging the vaginal fornices may help to release prostaglandins and stimulate uterine contractions. If the cervix is closed but soft, massage of the cervix may permit the insertion of a finger. If the cervix is favorable for sweeping, insert one finger in the cervix and rotate the finger in a circle to separate the amnion from the cervix.
- After the procedure. Provide the woman with a sanitary pad and recommend acetaminophen and a warm bath if she has discomfort or painful contractions. Advise her to come to the maternity unit in the following situations: severe pain, significant bleeding, or spontaneous rupture of the membranes.
Membrane sweeping can be performed as frequently as every 3 days. Formal cervical ripening and induction of labor may need to be planned if membrane sweeping does not result in the initiation of regular contractions.
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