Seasonal Variations in the Prevalence of Hypertensive Disorders of Pregnancy among Iranian Women: A Three-Year, Retrospective Study

Background: Hypertensive disorders of pregnancy increase neonatal and maternal mortality and morbidity. Studies have reported different seasonal patterns of these disorders during pregnancy.

Objectives: We aimed to determine the seasonal prevalence of hypertensive disorders of pregnancy among women who gave birth at Ayatollah Taleghani Hospital, Ilam City, between 2017 and 2020.

Methods: This descriptive-analytical study involved 10,988 files of children born from June 2017 to May 2020 at Taleghani Hospital, Ilam City. Among them were 389 cases with hypertensive disorders during pregnancy, which were compared against 260 cases without hypertensive disorders (control group). Using a researcher-designed questionnaire, we collected data on demographics, pregnancy history, clinical information, and medical history. Data analysis was done in SPSS (V.16) using chi-squared, Fisher’s exact, Mann-Whitney U, and independent t-tests (P < 0.05).

Results: Out of 389 cases (3.54%) of hypertensive pregnancy disorders, 254 (65.3%) were preeclampsia, 105 (27.0%) were gestational hypertension, 26 (6.7%) were chronic hypertension, and four (1%) were eclampsia. The highest prevalence of hypertensive pregnancy disorders was during winter (4.70%), specifically in February (5.46%) and January (5.05%). The minimum was in autumn (2.57%), specifically in September (2.40%) and November (2.50%). The mean age of the mothers, the mean age of the pregnancy, delivery method, history of abortion, history of stillbirth, incidents and disorders of the placenta and umbilical cord, amniotic fluid, gestational diabetes, thyroid disorders, history of preeclampsia, and history of infertility all had a significant relationship with hypertensive disorders during pregnancy.

Conclusions: Hypertensive disorders of pregnancy have a seasonal pattern and are more prevalent during the year’s colder months.