Uterine electrical activity and cervical shortening in the midtrimester of pregnancy

To determine whether a correlation exists between increased uterine electrical activity and cervical length (CL) in the midtrimester of pregnancy.

In this case-control study, 312 asymptomatic nulliparous women underwent both uterine electromyographic assessment and ultrasound CL measurement between the 16th and 23rd weeks of a singleton pregnancy. The outcome measure was the difference in ultrasound CL measurement between the women found to have uterine action potentials on electromyography and those who did not.

Action potentials were detected in 66 (21.1%) of the 312 women; and compared with the remainder of the study population, cervical length was significantly shorter in these women (35.7+/-8.9 mm vs 38.8+/-7.9 mm; P<0.01 by the Mann-Whitney test).

Ultrasound CL measurement in the midtrimester was significantly shorter in women with increased uterine electrical activity.