The effect of gestational age and cervical length measurements in the prediction of spontaneous preterm birth in twin pregnancies: an individual patient level meta-analysis.

OBJECTIVE: To assess the effect of gestational age (GA) and cervical length (CL) measurements at transvaginal ultrasound (TVUS) in the prediction of preterm birth in twin pregnancy. DESIGN: Individual patient data (IPD) meta-analysis. SETTING: International multicentre study. POPULATION: Asymptomatic twin pregnancy. METHODS: MEDLINE and EMBASE searches were performed and IPD obtained from authors of relevant studies. Multinomial logistic regression analysis determined probabilities for birth at ≤28(+0) , 28(+1) to 32(+0) , 32(+1) to 36(+0) , and ≥36(+1) weeks as a function of GA at screening and CL measurements. MAIN OUTCOME MEASURES: Predicted probabilities for preterm birth at ≤28(+0) , 28(+1) to 32(+0) , and 32(+1) to 36(+0) . RESULTS: A total of 6188 CL measurements were performed on 4409 twin pregnancies in 12 studies. Both GA at screening and CL had a significant and non-linear effect on GA at birth. The best prediction of birth at ≤28(+0) weeks was provided by screening at ≤18(+0) weeks (P < 0.001), whereas the best prediction of birth between 28(+1) and 36(+0) weeks was provided by screening at ≥24(+0) weeks (P < 0.001). Negative prediction value of 100% for birth at ≤28(+0) weeks is achieved at CL 65 mm and 43 mm at ultrasound GA at ≤18(+0) weeks and at 22(+1) to 24(+0) weeks, respectively. CONCLUSION: In twin pregnancies, prediction of preterm birth depends on both CL and the GA at screening. When CL is <30 mm, screening at ≤18(+0) weeks is most predictive for birth at ≤28(+0) weeks. Later screening at >22(+0) weeks is most predictive of delivery at 28(+1) to 36(+0) weeks. In twins, we recommend CL screening in twins to commence from ≤18(+0) weeks. TWEETABLE ABSTRACT: An individual patient meta-analysis assessing gestation and CL in the prediction of preterm birth in twins.