title: Seasonal influence on the admittance of pre-eclampsia patients in Tygerberg Hospital.
abstract: BACKGROUND
  Previous studies suggest that the occurrence of pre-eclampsia is seasonally distributed. This retrospective study aims to determine whether there is a seasonal variation in the number of admissions and the prevalence of women with pre-eclampsiain Tygerberg Hospital, South Africa.
  
  
  METHODS
  The number of women admitted with a diagnosis of pre-eclampsia,eclampsia or haemolysis elevated liver enzymes low platelets (HELLP) syndrome (together called pre-eclampsia) was obtained from hospital records from 2002 to 2003 for each season and month. Associations were analysed with Odds Ratios(OR). Furthermore, these data was compared with the Cape Town temperatures recorded on each day over the period, as well as the total rainfall for each month. Bivariate logistic regression of the probability of pre-eclampsia on temperature and rainfall was performed.
  
  
  RESULTS
  Pre-eclampsia occurred in 11.5% of all admissions (1,329/11,585). The prevalence was highest in winter (13.6% pre-eclampsia patients from all admissions). Women admitted in winter had a higher risk of developing pre-eclampsia compared to those admitted in summer (OR = 1.69, 95% CI: 1.071.53). The risk of developing pre-eclampsia in June was higher than in February (summer in South Africa, reference month) (OR = 2.81, 95% CI:2.063.83). There was a significant correlation between the number of admissions with pre-eclampsia and the minimum daily temperature (r = -0.620, p = 0.032).
  
  
  CONCLUSIONS
  Pre-eclampsia occurs more frequently in winter at Tygerberg Hospital, South Africa. The findings have implications for future research related to the aetiology of pre-eclampsia as well as for clinical care.
authors.affiliation: Department of Obstetrics and Gynaecology, Tygerberg Hospital and University of Stellenbosch, Tygerberg, South Africa.
authors.forename: Annelies
authors.initials: A
authors.lastname: Immink
authors.forename: Sicco
authors.initials: S
authors.lastname: Scherjon
authors.forename: Ron
authors.initials: R
authors.lastname: Wolterbeek
authors.forename: D Wilhelm
authors.initials: DW
authors.lastname: Steyn
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D016017:Odds Ratio; D011225:Pre-Eclampsia / Q000453:epidemiology*; D011247:Pregnancy; D015995:Prevalence; D012189:Retrospective Studies; D012621:Seasons; D013019:South Africa / Q000453:epidemiology