Cervical length in the early second trimester for detection of triplet pregnancies at risk for preterm birth.

Objective: Preterm triplet delivery is common and has a tremendous impact on neonatal mortality and morbidity. We aimed at assessing early second-trimester cervical length as a means of detecting triplet pregnancies at risk for preterm birth.

Methods: Cervical length was measured in triplet pregnancies during weeks 14 to 20. Cervical length of less than 25 mm was used as a cutoff to divide individuals into 2 groups. Perinatal outcome parameters were compared between the 2 groups and included gestational age at delivery, birth weights, and neonatal intensive care unit admission rates. Sensitivity, specificity, and positive and negative predictive values were calculated for cervical length as a screening method for preterm birth.

Results: We evaluated 36 triplets during weeks 14 to 20. Cervical length of less than 25 mm was measured in 14 (group I), 12 of which were delivered before 32 weeks (mean +/- SD, 28.4 +/- 3.1 weeks). Four of 22 women with cervical length of greater than 25 mm (group II) had delivery before 32 weeks (mean, 30.1 +/- 1.8 weeks). The mean gestational age at delivery for all parturients from group II was 33.1 +/- 2.1 weeks (P < .05). Group I neonates had lower birth weights (972 versus 1889 g; P < .001) and higher rates of low 5-minute Apgar scores and neonatal intensive care unit admissions compared with group II neonates. The sensitivity of a shorter cervix as a predictor of preterm labor was 75%, with specificity of 90%, a positive predictive value of 83%, and a negative predictive value of 81%.

Conclusions: Cervical length of less than 25 mm at 14 to 20 weeks' gestation is associated with preterm delivery and adverse perinatal outcome in triplet pregnancies.