Gynecol Obstet Invest. 2008 Jan 30;66(1):22-26 [Epub ahead of print]
Seasonal Variation in Pre-Eclamptic Rate and Its Association with the
Ambient Temperature and Humidity in Early Pregnancy.
Tam WH, Sahota DS, Lau TK, Li CY, Fung TY.
Department of Obstetrics and Gynecology, The Chinese University of Hong
Kong, Hong Kong, SAR, China.
Aims:
To determine any relationship between ambient temperatures adjusted
for humidity at conception and the occurrence of pre-eclampsia.
Methods:
The
subjects were singleton primiparae delivered in a Teaching Hospital between
1995 and 2002. We studied the odds of developing pre-eclampsia across months
and investigated the association between the pre-eclamptic rates based on
the months of conception and the mean monthly heat index.
Results:
A total
of 245 (1.6%) women were diagnosed pre-eclampsia and eclampsia during the
study period. There was a significant association between the seasons of
conception and rate of pre-eclampsia (logistic regression Wald chi(2) = 9.2,
p = 0.03). Conceptions during summer had a higher risk of pre-eclampsia than
those during autumn (2.3 vs. 1.6%, OR 1.7, 95% CI 1.2-2.5). Women who
conceived in June had the highest risk of developing pre-eclampsia (OR 2.8,
95% CI 1.5-5.2) while women who conceived in October had the lowest after
adjusting for age. A 2-month time lag was observed between the peak pre-eclamptic
rate in women who conceived in June and the peak heat index in August.
Conclusion:
Singleton primiparous women who conceived in summer and had a
longer exposure to higher ambient temperature were at a greater risk of pre-eclampsia.
