A membrane sweep is a common method offered to pregnant individuals nearing or past their due date. This non-pharmacological procedure encourages labor onset and is often considered a preliminary step before medical induction. It aims to stimulate the body’s natural processes, potentially leading to a spontaneous birth.
What is a Membrane Sweep?
A membrane sweep involves a healthcare provider performing an internal vaginal examination. During this procedure, the provider inserts a gloved finger into the cervix and uses a circular motion to gently separate the amniotic sac from the lower part of the uterus. This physical separation releases natural chemicals called prostaglandins, which soften, thin, and dilate the cervix, preparing it for labor. A membrane sweep does not involve artificially breaking the amniotic waters, known as an amniotomy. For the procedure to be performed, the cervix must have already begun to dilate, allowing access to the membranes.
How Often Does it Lead to Labor?
Studies indicate a membrane sweep can increase the chances of spontaneous labor. Research suggests it is associated with a 24% increased likelihood of delivering within 48 hours and a 46% increased chance within a week. Compared to expectant management, membrane sweeping can reduce the need for formal medical induction.
One study found that approximately 7 out of 10 women who received a membrane sweep went into spontaneous labor, compared to about 6 out of 10 women who did not have the procedure. A comprehensive review indicated that membrane sweeping may lead to a spontaneous onset of labor with an average risk ratio of 1.21, an absolute risk difference of 12.5%. It has also been observed to reduce the incidence of pregnancies continuing beyond 41 weeks. A successful membrane sweep often results in labor beginning within two to seven days.
Factors Influencing the Outcome
Several factors influence the likelihood of a membrane sweep initiating labor. A primary factor is the ripeness or favorability of the cervix at the time of the procedure. Cervical ripeness is assessed using a Bishop Score, which considers dilation, effacement (thinning), consistency (softness), position, and fetal station. A higher Bishop Score, indicating a more favorable cervix, is associated with a greater chance of the sweep being effective.
Gestational age also plays a role, with sweeps more effective closer to or past the estimated due date, typically after 39 weeks. Parity, or whether a person has given birth before, can also be a consideration. Individuals who have previously delivered may have a cervix that is already somewhat softened, potentially making the sweep more effective.
Potential Experiences and Important Considerations
Individuals undergoing a membrane sweep may experience some discomfort during the procedure, often described as similar to a rough pelvic examination. Following the sweep, it is common to experience mild side effects, including cramping, light vaginal spotting, or irregular contractions. These sensations are temporary and indicate the body is responding to prostaglandin release. While these symptoms are normal, it is important to distinguish them from signs of active labor.
Informed consent is obtained before a membrane sweep, ensuring the individual understands the procedure, its benefits, and any risks. It is an elective procedure. Contacting a healthcare provider is advised if there is persistent or severe pain, heavy bleeding (more than typical spotting), or any fluid leakage, which could indicate the waters have broken.