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Pelvic Exam in Late Pregnancy
About this time in your pregnancy, your healthcare provider may do a pelvic exam. This pelvic exam helps your caregiver evaluate the progress of your pregnancy. One of the first things he or she will observe is whether you are leaking amniotic fluid. If you think you are, it's important to tell your caregiver.

Your healthcare provider will examine your cervix at the pelvic exam. During labor, the cervix usually becomes softer and thins out. This process is called effacement. Your caregiver will evaluate the cervix for its softness or firmness and the amount of thinning.

Before labor begins, the cervix is thick and is "0% effaced." When you're in active labor, the cervix thins out; when it is half-thinned, it is "50% effaced." Immediately before delivery, the cervix is "100% effaced" or "completely effaced."
The dilatation (amount of opening) of the cervix is also important. This is usually measured in centimeters. The cervix is fully open when the diameter of the cervical opening measures 10cm. The goal is to be a 10! Before labor begins, the cervix may be closed. Or it may be open a little way, such as lcm (0.4 inch). The goal of labor is the stretching and opening of the cervix so the baby fits through it and can pass out of the uterus.

Your caregiver also evaluates whether the baby's head, bottom or legs are coming first. (He or she may refer to a "presenting part.") The shape of your pelvic bones is also noted.

The station is then determined. Station describes the degree to which the presenting part of the baby has descended into the birth canal. If the baby's head is at a -2 station, it means the head is higher inside you than if it were at a +2 station. The 0 point is a bony landmark in the pelvis, the starting place of the birth canal.

Think of the birth canal as a tube going from the pelvic girdle down through the pelvis and out the vagina. The baby travels through this tube from the uterus. It's possible that you may dilate during labor but the baby doesn't move down through the pelvis. In this case, a (-section may be called for because the baby's head doesn't fit through the pelvic girdle.

What Can Your Doctor Tell from a Pelvic Exam?
When your doctor examines you, he or she may describe your situation in medical terms. You might hear you are "2cm, 50% and a -2 station." This means the cervix is open 2cm (about 1 inch), it is halfway thinned out (50% effaced) and the presenting part (baby's head, feet or buttocks) is at a -2 station.

Try to remember this information. It's helpful when you go to the hospital and are checked there by a nurse or doctor. You can tell the medical personnel in labor and delivery what your dilatation and effacement were at your last checkup so they can know if your situation has changed.

There is actually sound medical reasoning for the idea that sex might bring on labor. But there is little clinical evidence that intercourse influences the outcome of normal pregnancies.