The association of first trimester uterine arteries Doppler velocimetry with different clinical phenotypes of hypertensive disorders of pregnancy : a longitudinal study

Introduction: Current classification of hypertensive disorders of pregnancy (HDP) is mostly based on temporal classification differentiating HDP according to early and late onset of the disease. However, epidemiological and clinical data suggest that there are two different clinical phenotypes of HDP that coexist at any gestational age: HDP associated to intrauterine growth restriction (HDP-IUGR) and HDP associated to appropriate for gestational age fetal growth (HDP-AGAf). The aim of the study was to evaluate the association of first trimester uterine arteries (UtA) by Doppler velocimetry, and maternal risk factors with HDP according to two different classifications: one based on gestational age at delivery (early- and late-HDP), and one based on longitudinal ultrasound evaluation of fetal growth (HDP-IUGR and HDP-AGAf), independently of the gestational age. Methods: Maternal characteristics and mean pulsatility index (PI) of UtA were collected at 11-13 gestational weeks. A longitudinal ultrasound follow-up of fetal growth in each trimester and clinical outcome were obtained in 4290 singleton pregnancies. Results: UtA-PI was significantly higher in women who developed HDP-IUGR (n = 22) and the odds ratio (OR) to develop HDP-IUGR from 25 to 39 weeks was 8.6 (p < .0001). HDP-AGAf (n = 112) was significantly associated with a higher BMI, multiparity, and maternal age, but not with UtA-PI (OR 1.3; p = .2). In women with an abnormal UtA-PI, the odds of developing early (n = 15) and late-HDP (n = 119) were 3.0 (p = .03) and 1.7 (p = .002), respectively. The AUCs for HDP-IUGR and early-HDP were 0.84 and 0.71, respectively. Discussion: UtA Doppler velocimetry in the first trimester was strongly associated with HDP-IUGR all along gestation, as a proxy of placental insufficiency, and showed no association with HDP-AGAf. Our findings suggest an efficacy of first trimester UtA Doppler velocimetry to identify HDP-IUGR independently of the gestational age, and a limited value for HDP not associated with intrauterine growth restriction (IUGR).