title: Maternal exposure to first-trimester sunshine is associated with increased birth weight in human infants.
abstract: 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.
authors.affiliation: Psychology Department, University of Otago, Dunedin, New Zealand. tuska194@student.otago.ac.nz
authors.forename: Karen
authors.initials: K
authors.lastname: Tustin
authors.forename: Julien
authors.initials: J
authors.lastname: Gross
authors.forename: Harlene
authors.initials: H
authors.lastname: Hayne
mesh_terms: D000328:Adult; D005260:Female; D047109:Fetal Development / Q000502:physiology; D051272:Glucose Transporter Type 1; D051274:Glucose Transporter Type 3; D019382:Human Growth Hormone / Q000502:physiology; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007334:Insulin-Like Growth Factor I / Q000502:physiology*; D009004:Monosaccharide Transport Proteins / Q000502:physiology; D009035:Mothers / Q000523:psychology*; D009419:Nerve Tissue Proteins / Q000502:physiology; D011247:Pregnancy; D011263:Pregnancy Trimester, Third / Q000502:physiology*; D013472:Sunlight
chemical_list: D051272:Glucose Transporter Type 1; D051274:Glucose Transporter Type 3; D009004:Monosaccharide Transport Proteins; D009419:Nerve Tissue Proteins; C495677:SLC2A1 protein, human; C495687:SLC2A3 protein, human; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I