Estimated birth weight and adult cardiovascular risk factors in a developing southern Chinese population: a cross sectional study

Abstract

BackgroundBirth weight is negatively associated with cardiovascular diseases and diabetes, but the associations are less well-established in developing populations where birth weight is often unavailable. We studied the association of birth weight and cardiovascular risk, using birth rank as an instrumental variable, in Southern China.MethodsWe used published data on birth weight by birth rank from an appropriate population and baseline data from the Guangzhou Biobank Cohort Study phases 2 & 3 (2005-8) to examine the adjusted associations, using instrumental variable analysis, of birth weight with clinically measured cardiovascular risk factors and the metabolic syndrome in older (≥ 50 years) men (n = 5,051) and women (n = 13,907).ResultsEstimated birth weight was associated with lower blood pressure (systolic -0.25 mm Hg 95% confidence interval (CI), -0.53 to 0.03 and diastolic -0.33 mm Hg 95% CI -0.48 to -0.18 per standard deviation higher birth weight), but had little association with glucose, lipids, waist-hip ratio, body mass index or the metabolic syndrome, adjusted for age, sex, early environment and number of offspring.ConclusionBirth weight may impact blood pressure; however associations of birth weight with other cardiovascular risk factors may not be related to foetal exposures, but speculatively could be an historical co-incidence, with corresponding implications for prevention.

Birth weight and risk of ischemic heart disease: A Mendelian randomization study

“…Diabetes is a strong predictor of CAD/MI, however it is becoming increasingly evident that factors do not always have the same effect on diabetes and CAD/MI, such as lipids or statins29. Our findings for lipids are fairly consistent with well-conducted observational studies30 and instrumental variable analysis using birth rank as an instrument for birth weight9, which found no association of birth weight with HDL and triglycerides. Our findings do not exclude the possibility of a small association of higher birth weight with lower HDL-cholesterol.…”

“…Our findings do not exclude the possibility of a small association of higher birth weight with lower HDL-cholesterol. Such an association, if it exists, might have been obscured by negative confounding by socio-economic position in previous observational studies30 and by lack of power in studies using instrumental variable analysis9.…”

“…To date, studies using instruments, such as birth rank9, or twin status10, have suggested little association of birth weight with blood pressure or cardiovascular disease risk factors but birth rank and twin status are of uncertain validity as instruments for birth weight. In contrast, comparing risk of disease in people with genetically higher birth weight, i.e., using instrument variable analysis with genetic instruments, (Mendelian randomization (MR)) provides an increasingly popular means of obtaining unconfounded estimates of potentially confounded associations, because genetic determinants of birth weight are randomly allocated at conception, analogous to the randomization in randomized controlled trials, and hence allow estimation of the causal effect of birth weight on health, provided that the relevant assumptions are fulfilled.…”

Prospective cohort studies of birth weight and risk of obesity, diabetes, and hypertension in adulthood among the Chinese population

“…In the present study we found a J‐shaped relationship between birth weight and BMI at baseline, when participants were aged 40–74 years. Our finding of the lower birth weight–lower BMI relationship is in agreement with most previous studies conducted in Western populations, but is not consistent with studies conducted in Chinese adults . Based on data from the 2002 Chinese Nutrition and Health Survey, Yang et al found that compared with women born in 1964, those born during the worst famine years (1959, 1960, and 1961) had higher BMI and a higher prevalence of overweightedness as adults.…”

“…It has been suggested that adverse exposures in early life can “program” short stature and a predisposition to abdominal adiposity, as well as an insulin resistance and other cardiometabolic risk factors in adult life . Low birth weight has been associated with a higher risk of central obesity, measured as WHR, after adjusting for adult BMI, although results are not consistent . Low birth weight was also linked to larger WC and WHtR in Asian populations.…”