Second-trimester uterine artery Doppler and spontaneous preterm delivery.

OBJECTIVE

To assess the relationship between second-trimester uterine artery (UtA) Doppler measurements and spontaneous preterm delivery.

METHODS

This was a retrospective analysis of UtA Doppler findings at 18-23 weeks' gestation in 234 singleton pregnancies with spontaneous preterm labor and 5472 pregnancies delivered at term. Cases with fetal chromosomal or structural abnormalities, pre-eclampsia, small-for-gestational-age (SGA) fetuses, concurrent maternal disease, cervical cerclage or history of cone biopsy were excluded.

RESULTS

UtA mean resistance index (RI) and number of protodiastolic notches were not significantly different in the spontaneous preterm labor group compared to the normal group. The 62 preterm deliveries not preceded by spontaneous preterm premature rupture of membranes (PPROM) showed a significantly higher RI and prevalence of bilateral notches than cases of preterm deliveries preceded by PPROM (n = 172). However, this difference was not confirmed in a logistic regression model.

CONCLUSION

Despite pathological evidence suggesting that defective placentation is associated with spontaneous preterm delivery, second-trimester UtA resistance, as assessed by Doppler ultrasound investigation, is not different in pregnancies subsequently complicated by preterm labor compared to pregnancies delivered at term.