Pelvic exams in pregnancy vary depending on the doctor and the practice. Your cervix's dilation and effacement might be checked every week starting at week 36 (or earlier!), or not until week 38 or 39, or your OB might not do a vaginal exam until you're in labor.

At what point in pregnancy do they start checking your cervix?

Prenatal visits:

Beginning at 36 weeks, we will check your cervix for signs of impending labor.

How do doctors tell if you are effaced?

Measuring effacement

Effacement is measured in percentages ranging from 0 to 100 percent. You're considered 0 percent effaced if your cervix is longer than 2 centimeters, around the length of the neck of a standard wine bottle. When you're 50 percent effaced, the cervix is around the length of the neck of a Mason jar.