Seasonal variation of the onset of preeclampsia and eclampsia

BACKGROUND: Preeclampsia is one of the three leading causes of maternal mortality. Studies have suggested that the incidence of preeclampsia may be partially dependent on the month or season of delivery. This study was conducted to evaluate whether seasonal variation has any effect on the incidence of eclampsia or preeclampsia. METHODS: From 1999 to 2001, a cross-sectional study in Alzahra Hospital was performed using all deliveries with gestational age more than 20 weeks. Variables of matemal age, parity, occurrence of preeclampsia and eclampsia, and season were evaluated and analyzed by chi-square test in SPSS 10. RESULTS: During the period of the study, there were 12,142 deliveries at Alzahra Hospital in Rasht. There were 2,579 (21.3%) deliveries in spring, 2,696 (22.2%) in summer, 3,645 (30%) in autumn, and 3,222 (26.5%) in winter. There was no statistically significant relationship between the age, parity and season. Hypertensive disorder was reported in 609 pregnancies (5%), with 11,533 (95%) having no hypertensive disorder. Data showed that 397 patients (3.3%) had preeclampsia and eclampsia. The highest rate of preeclampsia was in spring (3.6%), and the lowest rate was in summer (3%), but it revealed no statistical difference in the incidence of preeclampsia with season. CONCLUSIONS: We found no correlation between preeclampsia or eclampsia and season. It may be due to relative similarities between seasons in North of Iran. For example, there are relative similarities between spring and summer, and between autumn and winter.