Association between low birth weight and elevated white blood cell count in adulthood within a Japanese population

Background: Epidemiological studies have demonstrated the association between low birth weight and increased adulthood risk for cardiovascular and metabolic diseases. However, the precise mechanism underlying the association remains poorly understood. We investigated the association between birth weight and adult white blood cell (WBC) count in a Japanese population. Methods and Results: The subjects were 779 men and 209 women aged 35-64 years. The mean WBC count was 5,283 /μl (SD: 1,326). Birth weight was divided to 6 categories: <2,500, 2,500-<2,800, 2,800-<3,000, 3,000-<3,200, 3,200-<3,500, and >3,500 g. Estimated WBC counts were 5,729, 5,341, 5,301, 5,212, 5,013 and 5,372 for the subjects with birth weights of the above respective categories (p=0.015, trend p=0.016) by one-way analysis of covariance after adjustments for sex, age, height, body mass index (BMI), lifestyles, and chronic diseases. This association was pronounced among the subjects with a BMI <25.0 kg/m ² rather than those with a higher BMI. Conclusions: These findings support the idea that part of the association of low birth weight with elevated risk for vascular and metabolic diseases in later life could be mediated by an inflammatory pathway.