Two large prospective cohort studies from Shanghai, China showed that the risk of type 2 diabetes was higher among both men and women of low birthweight later in life, with a trend toward increased risk of hypertension as well.
Waist-to-hip ratio and waist-to-height ratio were found to be better indicators of central obesity compared to waist circumference alone.
Low birth weight was associated with increased type 2 diabetes risk in adulthood, a Chinese study found.
Among a large cohort, babies who were born with low birth weight -- under 2,500 grams (5.5 lbs) -- had a higher risk for developing type 2 diabetes later in life compared to babies born weighing 2,500-3,499 grams (HR 1.29, 95% CI 1.07-1.54, P for trend=0.0019), according to Wang-Hong Xu, of Fudan University School of Public Health in Shanghai, and colleagues.
Appearing in the Journal of Diabetes, this excess diabetes risk was decreased in those with higher birth weights. Compared with those born weighing 2,500-3,499 grams (5.5-7.7 lbs), babies weighing 3,500-3,999 grams (7.7-8.8 lbs) or 4,000 grams or more (≥8.8 lbs) had a lower risk for type 2 diabetes throughout life (HR 0.89, 95% CI 0.78-1.01 and HR 0.90, 95% CI 0.78-1.03, respectively).
"The associations were observed even after adjusting for most socioeconomic and lifestyle factors in adulthood, such as educational level, per capita income, smoking, alcohol consumption, and regular exercise," explained Xu in a statement. "These results suggest an important role of maternal and child health in prevention of non-communicable diseases in China and other low- and middle-income countries."
The researchers explained that these outcomes are likely due to metabolic programming during the in utero period. "Metabolic programming that promotes nutrient storage occurs in order to provide a survival advantage under conditions of poor postnatal nutrition," they wrote. "However, these adaptations can lead to the subsequent development of metabolic diseases, particularly under conditions of adequate postnatal nutrition or overnutrition."
A similar trend was also observed for hypertension risk, with the lowest birth weight group seeing the highest risk of hypertension later in life, although this difference wasn't statistically significant (P for trend=0.67):
3,500-3,999 g (7.7-8.8 lbs): HR 1.02 (95% CI 0.97-1.07)
≥4,000 g (8.8 lbs): HR 1.04 (95% CI 0.99-1.10)
And those born at the highest birth weight had the highest odds for overall obesity (P for overall significance<0.0001):
Birth weight in 10th percentile (2,500 g/5.5 lb): OR 0.73 (95% CI 0.67-0.79)
30th/40th percentile (3,000 g/6.6 lb): OR 0.89 (95% CI 0.86-0.92)
50th percentile (3,100 g/6.8 lb): OR 1.00 (Reference)
70th percentile (3,500 g/7.7 lb): OR 1.32 (95% CI 1.25-1.39)
90th percentile (4,000 g/8.8 lb): OR 1.53 (95% CI 1.40-1.67)
However, the researchers pointed out that this risk was different according to obesity type, with no significant relationship reported between birth weight and developing central obesity measured by waist circumference. Interestingly, there was actually a lower risk for central obesity measured by waist-to-hip ratio (WHR), as well as waist-to-height ratio (WHtR) seen among those born at a higher birth weight.
"These results indicate that Chinese men and women with low birth weight may have a relatively small body size (i.e., shorter stature and smaller waist and hip circumference)," the researchers explained, adding that "in this population, WHR and WHtR, which are considered superior to waist circumference for predicting adverse health outcomes, may be better indicators for birth weight-related central obesity."
For this study, the researchers drew upon two prospective cohort studies in China -- the Shanghai Women's Health Study and the Shanghai Men's Health Study. At the time of recruitment, the 13,569 women included in the study were ages 40 to 70, and the 11,515 men in the study were ages 40 to 74. Data on blood pressure and other anthropomorphic measures were obtained by professionals, while history of birth weight, type 2 diabetes, and hypertension were all self-reported by the participants (a study limitation, the authors said). Among this cohort, 5.3% men and 6.9% of women were born with low birth weight. Both men and women who were born at a higher birth weight were also more likely to have been breastfed as infants.
Other limitations of the study included the inclusion of only approximately one-third of study participants who reported birth weight, and a population drawn from Shanghai, which is China's most economically advanced urban center.