Is birth weight modified during pregnancy? Using sibling differences to understand the impact of blood glucose, obesity, and maternal weight gain in gestational diabetes.
OBJECTIVE
The purpose of this study was to examine the extent to which blood glucose, obesity, and maternal weight gain explains differences in birth weight using offspring sibling pairs in gestational diabetes mellitus (GDM).


METHODS
A retrospective analysis of 90 women with at least 2 GDM pregnancies was conducted. A fixed effects model was used to examine differences between siblings of the same mother (within-women), and results were contrasted with a multivariable regression model that compared different mothers (between-women).


RESULTS
Higher maternal weight gain was significantly associated with increased birth weight within mothers, but not between different women. Conversely, overweight status (body mass index [BMI] > or = 25) was significant between-mothers, but not within an individual mother's pregnancies. One-hour postprandial glucose was significant between-mothers, with a weaker association within-mothers. There was no association between fasting glucose and birth weight in either analysis.


CONCLUSIONS
Controlling pregnancy weight gain may reduce offspring birth weight in individual women with GDM, while the association between high birth weight and elevated prepregnancy BMI may represent a predisposition to both characteristics.
Hutcheon
Jennifer A
JA
Department of Epidemiology and Biostatistics, McGill University, Montreal, Quebec, Canada.
Platt
Robert W
RW
Meltzer
Sara J
SJ
Egeland
Grace M
GM
D000328:Adult; D001724:Birth Weight / Q000502:physiology*; D001786:Blood Glucose / Q000032:analysis*; D015992:Body Mass Index; D016640:Diabetes, Gestational / Q000503:physiopathology*; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008423:Maternal Age; D011247:Pregnancy; D012189:Retrospective Studies; D012307:Risk Factors; D035781:Siblings; D015430:Weight Gain / Q000502:physiology*
D001786:Blood Glucose