The objective of this study is to assess the association between birth weight and overweight/obesity in adults. The following MeSH terms were used: "birth weight," "obesity," "overweight." Fifteen studies involving a total of 211,457 persons were identified. Low birth weight (<2,500 g), as compared with normal birth weight (2,500-4,000 g), was not associated with increased risk of overweight/obesity (OR = 1.17, 95% CI 0.94, 1.46). High birth weight (≥ 4,000 g), as compared with normal birth weight, was associated with increased risk of overweight/obesity (OR = 1.46, 95% CI 1.27, 1.68). Low birth weight compared with normal birth weight, the total mean difference of BMI decreased 0.14 kg/m(2). High birth weight compared with normal birth weight, the total mean difference of BMI increased 0.76 kg/m(2). Low birth weight, as compared with a birth weight of ≥ 2,500 g, was not significantly associated with decreased risk of obesity (OR = 1.12, 95% CI 0.90-1.40). High birth weight, as compared with a birth weight of <4,000 g, was associated with increased risk of obesity (OR = 1.43, 95% CI 1.25-1.64). Low birth weight compared with birth weight ≥ 2,500 g, the total mean difference of BMI was decreased 0.42 kg/m(2); high birth weight compared with birth weight <4,000 g, the total mean difference of BMI was increased 0.79 kg/m(2).
Conclusion: Neither positively linear nor J- or U-shaped relations exist between birth weight and overweight/obesity in adults. It is high birth weight, not low birth weight, that is associated with increased risk of overweight/obesity in adults.