Folic acid intake during pregnancy reduced the incidence of pregnancy-induced hypertension in Tibetan Nationality of Tibet Plateau: a population based cohort study

Objective: The objective of this study was to investigate the effect of maternal supplementation with folic acid on pregnancy induced hypertension (PIH) and fetal outcomes in Tibetan Nationality of Tibet Plateau . Design: A retrospective cohort study. Setting: Lasha People's Hospital, China Participants Pregnant mothers of Tibetan Nationality on Tibet Plateau from Jan 2012 to Jan 2016. Primary and secondary outcomes Negative maternal and fetal outcomes between mothers who received folic acid supplement and mothers did not. Frequency of pregnancy induced hypertension were main outcome. Results: 6700 pregnant women were included in the study, 18.37% (1231/6700) mothers (group A)received folic acid supplement during pregnancy and 24.37%(300/1231) of them(group A1) having supplement of folic acid longer than 3months. 1230 mothers did not receive folic acid supplement were selected as control (group B) through propensity score matching. In comparison, mothers of group A have a lower frequency of PIH than group B ( 5.8 % vs.19.3 %, P<0.001), including gestational hypertension (1.87%vs.4.47 % ), mild Pre-eclampsia (2.11 %vs.5.69 % ) ,severe Pre-eclampsia(1.87% vs.8.54 %) and Eclampsia(0% vs.0.57% ). However, Longer duration of folic acid supplement did not reduced the incidence of PIH. Before delivery, mothers of group A had less anemia ( 31.7 %vs.20.1%, P <0.001) and much higher hemoglobin (122.3±16.02g vs.115.5±16.76g, P <0.001) than group B. After delivery, more preterm infants, more neonatal asphyxia , lighter weight, shorter height , smaller head circumference and pediatric admission were observed in infants of group B than group A. Conclusion: Among pregnant women of Tibetan Nationality on Tibet Plateau , folic acid supplement could reduce the incidence of pregnancy induced hypertension, anemia and related negative outcomes of infants.