Hypertensive disorders during pregnancy as a major cause of preterm birth and adverse perinatal outcomes: findings from a Brazilian National Survey.

Objective: This study aimed to evaluate the prevalence of hypertensive disorders during pregnancy among Brazilian women with preterm births and to compare the epidemiological characteristics and perinatal outcomes among preterm births of women with and without hypertension.
Methods: This was a secondary cross-sectional analysis of the Brazilian Multicenter Study on Preterm Birth. During the study period, all women with preterm births were included and further split into two groups according to the occurrence of any hypertensive disorder during pregnancy. Prevalence ratios were calculated for each variable. Maternal characteristics, prenatal care, and gestational and perinatal outcomes were compared between the two groups using χ2 and t-tests.
Results: A total of 4,150 women with preterm births were included, and 1,169 (28.2%) were identified as having hypertensive disorders. Advanced maternal age (prevalence ratio (PR) 2.49) and obesity (PR= 2.64) were more common in the hypertensive group. The gestational outcomes were worse in women with hypertension. Early preterm births were also more frequent in women with hypertension.
Conclusion: Hypertensive disorders of pregnancy were frequent among women with preterm births, and provider-initiated preterm births were the leading causes of premature births in this group. The factors significantly associated with hypertensive disorders among women with preterm births were obesity, excessive weight gain, and higher maternal age.