Placental morphometry in hypertensive disorders of pregnancy and its relationship with birth weight in a Latin American population.

ABSTRACT

OBJECTIVE: To assess the placental morphometry in pregnancies with hypertensive disorders of pregnancy (HDP) and its relationship with birth weight (BW). STUDY DESIGN: Cohort study of placental morphometry and fetal outcomes of 954 pregnancies at a university hospital in Ribeirão Preto, São Paulo, Brazil, in 2010. HDP categories were chronic (CH), gestational (GH), preeclampsia (PRE) and pre-eclampsia superimposed on chronic hypertension (CH + PRE). Associations between BW and placental measures (PM) in pregnancies were evaluated by multiple linear regression analyses. MAIN OUTCOME MEASURES (PM) Placental weight (PW, g), largest and smallest diameters (cm), thickness (cm), eccentricity, area (cm2), volume (cm3), BW/PW ratio and PW/BW ratio (efficiency). RESULTS: The frequencies of each HDP categories were 6.5% CH; 7.6% GH; 6.1% PRE, and 2.0% CH + PRE. PW, largest and smallest diameters, area and BW/PW ratio were statistically different between HDP and the normotensive group, with the lowest values for CH + PRE; the remaining measures showed no difference. BW was lower in HDP than in the normotensive group (p = 0.016). BW and PW were highly correlated in the presence of HDP (r = 0.79, p < 0.001). Sixty-seven percent of BW variability was accounted for PM (p < 0.001), and increased to 81% when maternal variables, gestational age and sex were added (p < 0.001). CONCLUSIONS: Hypertensive disorders of pregnancy significantly influence the growth of both the placenta and the fetus. PM explain 67% of BW variability, and CH + PRE was the category with the strongest association to the results.