Prediction of spontaneous preterm birth before 34 weeks in twin pregnancies using first-trimester cervical length

The aim of this retrospective cohort study with a case-control analysis, based on routinely collected data was to examine whether cervical length (CL) measurement in the first trimester independently contributes to the prediction of spontaneous preterm birth (PTB) before 34 weeks' gestation in twin pregnancies.

In the study period, 2781 twin pregnancies were booked for routine pregnancy care in five fetal medicine centres in Poland in the years 2015-2023. The inclusion criteria were monochorionic or dichorionic twin pregnancy with two life fetuses at the time of the 11-13 weeks' scan without any major abnormality. Univariate and multivariate regression logistic analysis was conducted to define which maternal and pregnancy characteristics provided an independent contribution in the prediction of spontaneous PTB before 34 weeks' gestation.

Among 2781 twin pregnancies booked for routine pregnancy care at 11-13 weeks, 2004 met qualification criteria for the study. Univariable regression analysis showed that the most significant biophysical risk factor of spontaneous PTB in twins was CL below 30 mm (OR = 4.85; 3.16-7.43). Also, CL < 35 mm was associated with an increased risk of PTB (OR = 3.42; 95%CI: 2.37-4.54). The most important maternal risk factor of PTB was obstetric history of PTD among multiparas (OR = 19.15, 95%CI: 8.22-44.58) and medical history of diabetes mellitus type 1 and 2 (OR = 3.49, 95%CI: 1.98-6.17) in the index pregnancy. However, multivariable regression analysis showed that the only factor that significantly increased the risk of spontaneous PTB in twins was obstetric history of PTB.

We showed that CL measurement in the first trimester of pregnancy in twin gestations may be useful in predicting preterm birth before 34 weeks of gestation.