Membrane sweep: what to expect, and does it work?

During an internal examination, a midwife or doctor sweeps a finger around your cervix. This separates the membranes around your baby from the cervix, which is thought to release hormones that may help start labour.

The NHS says a sweep is usually offered after 39 weeks, before induction is arranged. Induction is then offered if labour hasn’t started by 41 weeks. Timing varies between countries and hospitals, and you can say no.

One NHS Scotland guideline says a sweep isn’t suitable in these situations, so your team will check first:

• You have confirmed placenta praevia
• You’ve had unexplained bleeding in the third trimester
• The baby’s head is high and not in the pelvis
• A vaginal birth isn’t planned or isn’t suitable

It can be uncomfortable, and it can cause some cramping or light bleeding afterwards. Tell whoever is doing it if you want them to stop.

It may help, but the evidence isn’t strong. A 2020 Cochrane review of 44 studies found that people who had a sweep may be somewhat more likely to go into labour on their own and less likely to need a formal induction, but it rated that evidence as low certainty. It found little or no difference in caesarean rates.

A 2025 review of 34 trials reached a similar conclusion. It’s still not clear how many sweeps work best or when they should be done. If labour doesn’t start, you may be offered another sweep or induction.

Some cramping and light spotting can be expected. Call your maternity unit straight away if your waters break, you have vaginal bleeding beyond light spotting, your baby is moving less than usual, a contraction lasts more than 2 minutes, or you have 6 or more contractions in 10 minutes. See all the signs of labour.