Uterine activity characteristics in multiple gestations.

The frequency of uterine contractions has been shown to be increased during the 24-48 hours before the diagnosis of preterm labor in singleton gestations. Experience has indicated that there is also an increase in baseline uterine activity in twin gestations beyond that seen in women with singleton pregnancies. In this study, patients with twin gestations (39), triplet pregnancies (20), and quadruplets (ten) were monitored in the home daily for uterine activity. The results indicate that uterine activity was increased slightly within 48 hours of the onset of their initial preterm labor episode and significantly increased over baseline during the 24 hours preceding the diagnosis of preterm labor. This uterine activity led to evaluation for preterm labor before advanced dilatation occurred so that the majority of patients continued their pregnancy for more than 48 hours after diagnosis. Tocolytics did not have an effect on the crescendo of uterine activity preceding preterm labor. In this study, the crescendo of uterine activity occurred in multifetal gestations within 24 hours of preterm labor, as has been described for singleton pregnancies.