How many vaginal ultrasounds do most women receive in pregnancy and at which weeks of pregnancy do u have them?

Depends: If it is a normal (low risk) pregnancy usually 2-4. High-risk pregnancies can have many more.

One: Usually there is only one transvaginal ultrasound; although some offices never use this technique. Dependent on size of patient, even in early pregnancy a "regular" or transabbdominal us will be done. Typically, a 20 week screening (not vaginal) is done as well.

Depends: Sometimes a very early vaginal ultrasound is done to asses for a fetal heart beat and a follow up is needed to accurately date. If all is normal you may not need a additional tv ultrasound.