Birth weight of offspring and insulin resistance in late adulthood: cross sectional survey

JM Howard, D Banerjee and H Khan all suggest alternative (to the
foetal insulin hypothesis) explanations for the associations between
offspring birthweight and maternal insulin resistance in later life. We
agree that these are all possible explanations - our conclusion was that
common genetic factors contribute to the relationship between birth weight
and cardiovascular disease and diabetes mellitus in adults.[1] The
possible explanations presented by these authors are unlikely to explain
the associations between low offspring birth weight and a father's
cardiovascular disease and diabetes risk. This association has been found
in several studies that were cited in our paper [2][3][4] and one
additional study not cited.[5] The most plausible explanation for these
associations is genetic. Interestingly the associations between offspring
birthweight and paternal disease risk tend to be weaker than those between
offspring birthweight and maternal disease risk. We feel that genetic
factors and maternal environmental factors play a part in the trans-
generational associations between birth weight and cardiovascular
disease[6] and agree with A Banerjee that these associations are likely to
be complex and multi-factorial. D Banerjee states that the possibility
that low offspring birth weight is also related to hypertension in the
mothers is yet to be tested - but we present data on the inverse
association between offspring birthweight and systolic blood pressure in
our paper.[1] A Banerjee asks about the causes of low birth weight - for
women in this cohort we do not have these data. However, the association
of offspring birthweight with insulin resistance was linear across the
birthweight distribution and therefore unlikely to be explained by
specific causes of low birthweight at just one end of the distribution. S
Stadnaro suggests an interesting clinical 'bed-side' method for assessing
insulin resistance status - we are not convinced that this is valid or
reliable for epidemiological studies or clinical practice.

Debbie A Lawlor, George Davey Smith, Shah Ebrahim
Department of Social Medicine, University of Bristol

References

1. Lawlor DA, Davey Smith G, Ebrahim S. Birth weight of offspring and
insulin resistance in late adulthood: cross sectional survey. BMJ
2002;325:359-562.

2. Davey Smith G, Hart C, Ferrell C, et al. Birth weight of offspring
and mortality in the Renfrew and Paisley study: prospective observational
study. BMJ 1997;315:1189-1193.

3. Rasmussen F, Sterne J, Davey Smith G, Tynelius P, Leon DA. Fetal
growth is associated with parents' cardiovascular mortality. Am J
Epidemiol 1992 135:266-273 2001;153 (Suppl):S98.

4. Rasmussen F, Davey Smith G, Sterne J, Tynelius P, Leon DA. Birth
characteristics of offspring and parental diabetes. Am J Epidemiol
2001;153 (Suppl): S47

5. Lawlor DA, Davey Smith G, Whincup P, Wannamethee G, Papacosta O,
Dhanjil S, Griffin M, Nicolaides AN, Ebrahim S. The association between
offspring birth weight and atherosclerosis in middle aged men and women:
British Regional Heart Study. J Epidemiol & Community Health 2002 (in
press)

6. Lawlor DA, Davey Smith G, Ebrahim S. Association between leg length
and offspring birthweight: partial explanation for the transgenerational
associations between birthweight and cardiovascular disease. Paediatric
& Perinatal Epidemiology 2002 (in press)