First trimester placental volume is reduced in hypertensive disorders of pregnancy associated with small for gestational age fetus.

Introduction: Trophoblastic invasion and placental growth are critical for pregnancy outcome. The placental volume can be assessed by 3 D ultrasound using Virtual Organ Computer-aided Analysis (VOCAL). Epidemiological and clinical data suggest that there are two different clinical phenotypes of hypertensive disorders of pregnancy (HDP) that coexist at any gestational age: HDP associated to fetal growth impairment and HDP associated to appropriate for gestational age fetal growth. The aim of this study was to determine whether placental volume in the first trimester of pregnancy differs between women with HDP associated or not to fetal growth impairment and uncomplicated pregnancies.

Methods: This is a retrospective cross-sectional study of prospectively recruited data in which maternal characteristics, Doppler velocimetry of uterine arteries, and three-dimensional (3 D) volume of the placenta were collected at 11 + 1 - 13 + 6 gestational weeks. The placental quotient (PQ) was calculated as placental volume/crown rump length.

Results: In a 2-year period, we prospectively collected first trimester data of 1322 women. For the purposes of this cross-sectional study, 57 women that delivered a SGA fetus, 34 that developed HDP-AGA, and six that developed HDP-SGA, respectively, were included in the study as cases. The control group was made of 117 uncomplicated pregnancies. The PQ was higher in women with uncomplicated pregnancies (PQ median 16.36 cm/cm) than in all other study groups (PQ in SGA: 13.02 cm/cm,  < .001; PQ in HDP-AGA: 12.65 cm/cm,  = .002; and PQ in women with HDP-SGA: 8.33 cm/cm [IQR 6.50-10.13],  < .001). The lowest PQ was observed in women with HDP-SGA and was significantly lower than PQ in either women with SGA or those with HDP-AGA ( = .02 and  = .04, respectively). The mean uterine artery pulsatility index was the highest in women with HDP-SGA (median 2.30) compared to all other groups (uncomplicated pregnancies 1.48,  < .0001; women with SGA 1.59,  = .001; and women with HDP-AGA 1.75,  = .009).

Discussion: Our findings suggest that HDP associated with SGA is characterized by impaired placental growth and perfusion as soon as in the first trimester of pregnancy. The role of PQ, isolated or in association with other biophysical parameters, to predict HDP with fetal growth impairment remains to be evaluated.