Seasonal variation in the prevalence of preeclampsia

INTRODUCTION: Hypertension in pregnancy is one of the three factors of maternal mortality. Etiology of the disease is unknown, but the many factors contributing to the identification and control of it can be taken a step to prevent and reduce the symptoms of the disease. The purpose of this study was to determine the prevalence of preeclampsia (high-blood pressure) in different seasons of the year. METHODS: The present retrospective cross-sectional study was conducted on more than 8,000 pregnant women visiting Assali specialized hospital from 2011 to 2013. Required data was collected through questionnaire checklist. The Chi-square test with multiple comparisons was used to compare the frequencies of pregnancy-induced hypertension (PIH) according to the month of year, and adjustment of multiplicity was conducted using Bonferroni's method. Student's t-test was used to compare the means of PIH prevalence rates. In all analyses, P < 0.05 was taken to indicate statistical significance. RESULTS: In these 8000 woman admitted to labor, overall prevalence of PIH was 3.8 ± 0.6%. The prevalence rate of PIH was highest in the summer (4.5%) and lowest frequent in the winter (2.7%), respectively. In July, the prevalence rate was significantly higher than those for any other month (4.7%), and in March, it was lower prevalence than for any month (2.2%), respectively. Using the Chi-square test, a significant difference between the incidence of disease was observed in summer and winter (P < 0.001). CONCLUSION: The prevalence rate of PIH was higher for delivery in summer and early spring and lowest for winter delivery among Khorramabad women based on these results; it seems that changes in temperature and humidity in different seasons can affect preeclampsia, and preeclampsia increases with increasing frequency temperature.