The predictive value of the uterine artery pulsatility index during the early third trimester for the occurrence of adverse pregnancy outcomes depending on the maternal obesity

Purpose To identify the correlation between the pre-gravid maternal obesity and the uterine artery pulsatility index (UtA-PI) at 28-34 weeks' gestation, and to evaluate the predictive value of the UtA-PI for the occurrence of adverse outcomes depending on the maternal obesity. Methods Between January 2010 and December 2011, 229 pregnant women were prospectively observed and analyzed. The UtA-PI during 28-34 weeks' gestation was estimated, with abnormal UtA-PI defined if the value was above the 95th centile for gestational age. The patients were classified, using a cut-off value for body mass index (BMI) of 25 kg/m², into obese (pre-gravid BMI ≥ 25 kg/m²) and non-obese (pre-gravid BMI < 25 kg/m²) groups. We analyzed the association between the pre-gravid BMI and occurrence of abnormal UtA-PI and estimated their contributions to adverse outcomes using regression analyses. Results The occurrence of abnormal UtA-PI in the women with pre-gravid BMI over 25 kg/m² was significantly higher than those with normal pre-gravid BMI (OR: 2.49; 95% CI: 1.22-5.12). In multivariate analyses, the combination with abnormal UtA-PI and pre-gravid BMI over 25 kg/m² contributed to the occurrence of preterm delivery (OR: 33.5; 95% CI: 7.63-147.21), gestational diabetes (OR: 3.98; 95% CI: 1.17-13.56) and pregnancy induced hypertension (OR: 12.71; 95% CI: 3.45-46.87), compared to the control group with pre-gravid BMI of 25 kg/m² and less, and normal UtA-PI. Conclusion Women with pre-gravid BMI over 25 kg/m² show increased tendency of abnormal uterine artery pulsatility index during 28-34 weeks, which increases the risk of adverse pregnancy outcomes.