Effects of thalassemia minor on umbilical artery blood flow and perinatal outcomes in pregnancy: A retrospective cohort study

Objective The aim of the present study was to compare the fetal umbilical artery blood flow parameters in the third trimester and perinatal outcomes between pregnant women with and without thalassemia minor in South China. Methods This was a retrospective cohort study. Doppler ultrasound was used to detect fetal umbilical artery hemodynamics in pregnant women with or without thalassemia minor during the third trimester. The main parameters assessed were umbilical artery peak systolic flow velocity/end-diastolic flow velocity (S/D), resistance index (RI), pulsation index (PI), and relevant perinatal outcomes. Results This study included 540 pregnant women, 180 with thalassemia minor and 360 being healthy controls. In the third trimester, the thalassemia minor group had higher umbilical artery S/D (P = 0.002), RI (P = 0.002), and PI (P = 0.012) than healthy pregnant women, as well as lower levels of hemoglobin (Hb) (P < 0.001) and higher ferritin levels (P < 0.001). Compared to the non-thalassemia group, neonatal body weight in the thalassemia minor group was significantly lower (P = 0.001). Additionally, the incidence of maternal anemia (odds ratio [OR] 3.92; 95% confidence interval [CI]: 2.57-5.99, P < 0.001), low birth weight (OR 15.35; 95% CI: 1.71-137.93, P = 0.015), fetal distress (OR 2.18; 95% CI: 1.12-4.26, P = 0.023), neonatal asphyxia (OR 12.81; 95% CI: 1.40-117.33, P = 0.024), oligohydramnios (OR 18.25; 95% CI: 2.21-150.36, P = 0.007) and Apgar score <7 at 1 min after birth (OR 7.97; 95% CI: 1.53-41.54, P = 0.014) was significantly higher in the thalassemia minor group. Conclusion Pregnant women with thalassemia minor have higher umbilical artery S/D, RI and PI during the third trimester and a higher risk of adverse perinatal outcomes.