First‐trimester uterine artery Doppler and hypertensive disorders in twin pregnancies: Use of twin versus singleton references

Abstract

AbstractObjectiveTo determine the association of first‐trimester uterine artery Doppler with hypertensive disorders of pregnancy in twin pregnancies.MethodsThis was a retrospective cohort study of twin pregnancies followed at the University Hospital Center of Central Lisbon, Portugal, between January 2010 and December 2022. First‐trimester uterine artery pulsatility index (UtA‐PI) was determined and compared between twin pregnancies (n = 454) and singleton pregnancies (n = 908), matched to maternal and pregnancy characteristics. Maternal characteristics and mean UtA‐PI were analyzed for gestational age, birth weight, gestational hypertension, early‐ and late‐onset pre‐eclampsia, HELLP (hemolysis, elevated liver enzymes, low platelets) syndrome, and preterm birth. Univariable and multivariable logistic regression models were used.ResultsThe mean first‐trimester UtA‐PI was significantly lower in dichorionic twins than in singletons (P < 0.001). To study hypertensive disorders of pregnancy in twins, 390 pregnancies were included: 311 (79.7%) dichorionic and 79 (20.3%) monochorionic twins. The observed rates of early‐ and late‐onset pre‐eclampsia, gestational hypertension, and HELLP syndrome were 1.0%, 4.4%, 7.4%, and 1.5%, respectively. We achieved a 100% detection rate for early‐onset pre‐eclampsia using the UtA‐PI 90th centile for twins. However, when singleton references were considered, the detection rate decreased to 50%. UtA‐PI at or above the 95th centile was associated with increased odds for preterm birth before 32 weeks (adjusted odds ratio 4.1, 95% confidence interval 1.0–16.7, P = 0.043).ConclusionsUnless other major risk factors for hypertensive disorders are present, women with low UtA‐PI will probably not benefit from aspirin prophylaxis. Close monitoring of all twin pregnancies for hypertensive disorders is still recommended.