HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by MURRAY, L. J. Articles by EVANS, A. E. Search for Related Content PubMed PubMed Citation Articles by MURRAY, L. J. Articles by EVANS, A. E.

Season and Outdoor Ambient Temperature: Effects on Birth Weight

From the Departments of Epidemiology and Public Health, Health and Social Care Research Unit, Department of Geography, The Queens University of Belfast, Belfast, and the Department of Social Medicine, The University of Bristol, Bristol, United Kingdom.

Address reprint requests to: Liam J. Murray, MD Queen’s University Department of Epidemiology and Public Health Mulhouse Building, Royal Group of Hospitals Grosvenor Road Belfast, BT12 6BJ United Kingdom E-mail: l.murray{at}qub.ac.uk

Objective: To determine the extent to which meteorologic factors explain seasonality in birth weight in a developed country.

Methods: Recorded birth weights were collected for all singleton live births after 36 weeks of pregnancy in Northern Ireland between 1971 and 1986. Data on daily maximum and minimum temperatures, rainfall, and hours of bright sunshine were obtained from a local climatologic station for the same period. For each birth, mean daily maximum and minimum temperatures, rainfall, and hours of bright sunshine were calculated for the trimesters of the pregnancy. Linear regression models were constructed with birth weight as the dependent variable and month of birth as a predictor variable. Months of birth were entered in the models as dummy variables. Adjustment was made for year of birth, duration of gestation, maternal age, number of previous pregnancies, sex, and social class of infants at birth and for meteorologic variables relating to each trimester.

Results: A clear seasonal pattern in birth weight was observed, with lowest mean birth weight in late spring and summer. Adjusted mean birth weights were 25.5 g, 29.6 g, and 31.6 g lower in May, June, and July, respectively, than in January. This seasonal variation occurred in both sexes, and in female births, it disappeared almost entirely after adjustment for mean daily maximum temperature during the second trimester of pregnancy.

Conclusion: Infants born during late spring and summer are lighter than those born in winter, which might be the result of exposure to low winter temperatures during midgestation. Pregnant women should keep themselves warm during midpregnancy.

This article has been cited by other articles:

				A. Cagnacci, F. S. Pansini, A. Bacchi-Modena, N. Giulini, G. Mollica, D. De Aloysio, E. Vadora, A. Volpe, and for the Emilia-Romagna Operative Group for the Men Season of birth influences the timing of menopause Hum. Reprod., August 1, 2005; 20(8): 2190 - 2193. [Abstract] [Full Text] [PDF]

				D. Gunnell, F. Rasmussen, D. Fouskakis, P. Tynelius, and G. Harrison Patterns of Fetal and Childhood Growth and the Development of Psychosis in Young Males: A Cohort Study Am. J. Epidemiol., August 15, 2003; 158(4): 291 - 300. [Abstract] [Full Text] [PDF]

				J. J. McGrath Invited Commentary: Gaining Traction on the Epidemiologic Landscape of Schizophrenia Am. J. Epidemiol., August 15, 2003; 158(4): 301 - 304. [Full Text] [PDF]

				L. van Hanswijck de Jonge, G. Waller, and N. Stettler Ethnicity Modifies Seasonal Variations in Birth Weight and Weight Gain of Infants J. Nutr., May 1, 2003; 133(5): 1415 - 1418. [Abstract] [Full Text] [PDF]