Ultrasonic assessment of cervix in normal pregnancy.

We studied 30 normal pregnant women from the first trimester to 36 weeks. This group of women had had no previous miscarriage, termination of pregnancy, operations on the cervix, or premature labor. Fifteen were primigravidae and the remainder were multigravidae. There was no significant difference in the length of the cervix from 10 to 36 weeks of gestation (p greater than 0.05). The mean width of the cervix gradually increased from 10 to 36 weeks of gestation (p less than 0.01). The mean width of the cervical canal showed no significant change from 10 to 36 weeks of gestation (p greater than 0.05).