This is when your doctor or midwife uses a finger to separate the bag of waters from the lower part of your cervix. This can only be done if your cervix is dilated some, and common side effects include cramping and spotting.
Near the end of pregnancy, some women may want some help going into labor, either because they are uncomfortable or they want to avoid an induction. Membrane stripping or sweeping is one thing your doctor or midwife can do at a prenatal visit to try and help labor along. It is assumed that this releases prostaglandins, which cause uterine contractions. There is actual data that membrane stripping increases the chances you’ll go into labor within 48 hours, so it might be worth a try! And if it doesn’t work, try not to worry — it can be repeated at your next visit if need be.
Keep in mind that many providers will not do this until you are close to your due date, and some may not offer it if you have tested positive for Group B Strep bacteria (though there is no hard data this is not a reason to do it).