Birth weight is associated with risk for type 2 diabetes and CVD in a J-shaped manner, and is more pronounced among women, according to findings published in the Journal of the American Heart Association.
The meta-analysis aimed to clarify the shape of associations between birth weight, type 2 diabetes and CVD in adults and assessed sex-specific risks, the researchers wrote.
“Studies have consistently reported a U-shaped association between birth weight and [type 2 diabetes], while studies examining birth weight and CVD have been inconsistent, reporting an inverse or a U-shaped association,” Marianne Ravn Knop, MSc, a research associate at the Leadership Institute for Global Health Transformation at the Saw Swee Hock School of Public Health Transformation at the National University of Singapore, and colleagues wrote. “The inconsistency of these findings might be explained by differences in the definition of high birth weight.”
Researchers identified 49 studies assessing the association between birth weight and type 2 diabetes, 33 studies for CVD, and 53 studies for hypertension and high BP.
Sex-neutral and sex-specific dichotomous comparisons were performed using three different cutoffs for birth weight: 2.5 kg, 4 kg and 4.5 kg. According to the researchers, the 2.5-kg weight was in line with what most studies set as the threshold for low birth weight.
Researchers observed that participants with a birth weight more than 4.5 kg had a 19% higher risk for type 2 diabetes (OR = 1.19; 95% CI, 1.04-1.36) and a 22% higher risk for CVD (OR = 1.22; 95% CI, 1.08-1.37) compared with the reference birth weight group (4-4.5 kg).
Knop and colleagues performed categorical analyses on six birth weight groups and dose-response analyses showing J-shaped associations of birth weight with type 2 diabetes and CVD, which were more pronounced in women, while having an inverse association with hypertension.
The researchers wrote that the lowest risks for type 2 diabetes, CVD and hypertension were observed at 3.5 kg to 4 kg, 4 kg to 4.5 kg, and 4 kg to 4.5 kg birth weights, respectively.
Future studies assessing the association between birth weight and chronic disease later in life should explicitly investigate potential sex differences, they wrote.
“Sex might, in fact, act as an effect modifier rather than a confounder at the upper tail of the birth weight distribution,” Knop and colleagues wrote. “More investigations are required to uncover the true causal pre- and postnatal exposures for the development of strategies for primary prevention.” – by Earl Holland
Disclosures: The authors report no relevant financial disclosures.