First-trimester cervical length is predictive of spontaneous preterm birth before 34 weeks of gestation in twin pregnancies

Background The aim of this study was to examine if cervical length (CL) measurement in the first trimester provides an independent contribution in the prediction of spontaneous preterm birth (PTB) before 34 weeks’ gestation in twin pregnancies. Methods 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. Results 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 30mm (OR = 4.85; 3.16–7.43). Also, CL < 35mm 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 (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. Conclusions First trimester CL below 35 mm and obstetric history of spontaneous PTB are predictive of spontaneous preterm birth in twin gestations.