Maternal exposure to first-trimester sunshine is associated with increased birth weight in human infants
Article first published online: 17 NOV 2004
Copyright © 2004 Wiley Periodicals, Inc.
Volume 45, Issue 4, pages 221–230, December 2004
How to Cite
Tustin, K., Gross, J. and Hayne, H. (2004), Maternal exposure to first-trimester sunshine is associated with increased birth weight in human infants. Dev. Psychobiol., 45: 221–230. doi: 10.1002/dev.20030
- Issue published online: 17 NOV 2004
- Article first published online: 17 NOV 2004
- Manuscript Accepted: 19 JUL 2004
- Manuscript Received: 26 FEB 2004
- University of Otago. Grant Number: ORG200200520
- birth weight;
- ambient temperature;
- insulin-like growth factor;
- fetal growth
Two alternative hypotheses have been generated to account for seasonal variation in the birth weight of human infants born in industrialized countries. First, it has been hypothesized that low ambient temperature during the second trimester of gestation decreases birth weight. Second, it has been hypothesized that exposure to bright sunshine during the first trimester increases birth weight. We tested these two hypotheses to determine which, if either, accounted for seasonal variation in birth weight of full-term infants. Birth weight data, collected over a 5-year period, were analyzed as a function of peak and trough sunshine and ambient temperature. Although there was no effect of ambient temperature during any trimester on birth weight, infants whose mothers were exposed to peak sunshine during their first trimester were born significantly heavier than infants whose mothers experienced trough levels of sunshine during the same trimester. Furthermore, infants whose mothers were exposed to trough levels of sunshine during their second and third trimesters were born significantly heavier than infants whose mothers were exposed to peak levels of sunshine during the same trimesters. We hypothesize that high levels of sunshine during early gestation may increase the level of insulin-like growth factor (IGF)-1, facilitating prenatal growth. © 2004 Wiley Periodicals, Inc. Dev Psychobiol 45: 221–230, 2004.