Risk factors for hypertensive disorders in pregnancy in women residing in high altitude areas and their impacts on maternal and infant outcomes / 中华围产医学杂志

ABSTRACT

Objective:To investigate the incidence and risk factors of hypertensive disorders in pregnancy (HDP) in high altitude areas and their influence on maternal and infant outcomes.Methods:This was a retrospective case-control study. A total of 220 newborns were selected as the high altitude group, who were born to 216 mothers with HDP and admitted to the Neonatal Intensive Care Unit of the Lhasa People's Hospital from June 1, 2018, to June 1, 2020. The low altitude group consisted of 235 newborns born to 231 mothers with HDP and admitted to the Department of Neonatology of the Children's Hospital Affiliated to Beijing Capital Institute of Pediatrics from January 1, 2018, to December 31, 2021. Differences in the types of HDP between the two groups and the risk factors for the high incidence of preeclampsia-eclampsia and early-onset preeclampsia in high altitude area were analyzed. The influences of HDP in high and low altitude areas on maternal and infant outcomes were compared. Statistical analysis was performed using t-test, Mann-Whitney U test, Pearson Chi-square test, or continuous correction Chi-square test, and univariate and multivariate logistic regression analysis. Results:Maternal age and the proportions of primiparae and women of advanced age or having irregular prenatal examination were greater in the high altitude group than those in the low altitude group (all P<0.05). Besides, the incidence of early-onset preeclampsia, eclampsia, preeclampsia-eclampsia, and chronic hypertension complicated by preeclampsia were also higher in the high altitude group (all P<0.05). Multivariate logistic regression analysis showed that high altitude was a risk factor for the development of preeclampsia-eclampsia ( OR=4.437, 95% CI2.582-7.626). Adverse pregnancy history ( OR=2.576, 95% CI1.217-5.452) and irregular prenatal examination ( OR=2.862, 95% CI1.412-5.800) were independent risk factors for early-onset preeclampsia in pregnant women in high altitude areas. Twin-pregnancy was a protective factor for early-onset preeclampsia in pregnant women in high altitude areas ( OR=0.183, 95% CI 0.054-0.623). The incidence of maternal heart failure [7.9% (17/216) vs 0.4% (1/231), χ2=15.98], placental abruption [7.9% (17/216) vs 3.5% (8/231), χ2=4.11], hemolysis, elevated liver function and low platelet count syndrome [14.4% (31/216) vs 1.7% (4/231), χ2=24.64], premature delivery [86.1% (118/216) vs 73.6% (170/231), χ2=10.79], fetal growth restriction [52.3% (115/220) vs 18.7% (44/235), χ2=56.26], fetal distress [18.2% (40/220) vs 8.1% (19/235), χ2=10.26], neonatal asphyxia [29.5% (65/220) vs 11.1% (26/235), χ2=24.26], severe asphyxia [8.6% (19/220) vs 2.6% (6/235), χ2=8.10] and the proportion of neonates requiring mechanical ventilation within 24 h after birth [69.5% (153/220) vs 42.6% (100/235), χ2=33.54] as well as neonatal death within 7 d after birth [5.5% (12/220) vs 1.3% (3/235), χ2=6.22] in the high altitude group were significantly higher than those in the low altitude group (all P<0.05). Conclusion:High altitude is a risk factor for preeclampsia-eclampsia, and the adverse effects of HDP on mothers and infants are more severe in high altitude areas.