Breast feeding, maternal smoking and early atheroma

Maternal diet during pregnancy and carotid intima-media thickness in children

OBJECTIVE

Autopsy studies show that intimal lipid accumulations in arteries are often present at birth, suggesting that the prenatal environment plays a role in the pathogenesis of atherosclerosis. In animal models, a restricted or unbalanced maternal diet during gestation can influence susceptibility to atherosclerosis, but the relation in humans between maternal diet during pregnancy and atherogenesis is unknown.

METHODS AND RESULTS

We measured carotid intima-media thickness (IMT) in 216 nine-year-old children whose mothers had participated in a study of nutrition during pregnancy. IMT was greater in boys, in children who were heavier, in those with higher systolic blood pressure, and in those who took less exercise. Increased IMT was associated with a lower maternal energy intake in early (P=0.029) or late (P=0.006) pregnancy, after adjustment for these factors. Mean IMT of children whose mothers were in the lowest quarter of the distribution of energy intake in late pregnancy was 0.027 mm (95% confidence interval, 0.004 to 0.049) greater than that of those whose mothers were in the highest quarter of the distribution.

CONCLUSIONS

Lower maternal energy intake during pregnancy may increase the susceptibility to atherogenesis of the child.

Infant feeding and components of the metabolic syndrome: findings from the European Youth Heart Study

AIMS

To assess the associations of type and duration of infant feeding with components of the metabolic syndrome in children aged 9 and 15.

METHODS

A total of 2192 randomly selected schoolchildren aged 9 and 15 years from Estonia (n = 1174) and Denmark (n = 1018) were studied. Insulin resistance (homoeostasis model assessment), triglyceride levels, high density lipoprotein cholesterol, and systolic blood pressure were measured.

RESULTS

Children who had ever been exclusively breast fed had lower systolic blood pressures than those who were not. With full adjustment for age, sex, country, birth weight, pubertal stage, body mass index, height, maternal and paternal education, income, smoking, and body mass index the mean systolic blood pressure of children who had ever been breast fed was 1.7 mm Hg (95% CI -3.0 to -0.5) lower than those who had never been exclusively breast fed. There was a dose-response in this association with decreasing mean systolic blood pressure across categories from never exclusively breast fed to breast fed for more than six months. Exclusive breast feeding was not associated with other components of the metabolic syndrome. Results were similar when examined separately in each country.

CONCLUSIONS

The magnitude of the association, its independence of important confounding factors, and the dose-response suggest that exclusive breast feeding is causally associated with reduced systolic blood pressure. The magnitude of the effect we found with blood pressure is comparable to the published effects of salt restriction and physical activity on blood pressure in adult populations, suggesting that it is of public health importance.

Breastfeeding and atherosclerosis: intima-media thickness and plaques at 65-year follow-up of the Boyd Orr cohort

OBJECTIVES

The impact of breastfeeding in infancy on cardiovascular disease risk is uncertain. We related breastfeeding in infancy to atherosclerosis in adulthood.

METHODS AND RESULTS

A historic cohort study based on a 65-year follow-up of the Carnegie (Boyd Orr) survey of diet and health in prewar Britain, 1937 to 1939. A total of 732 eligible cohort members living in or around Aberdeen, Bristol, Dundee, Wisbech, and London were invited for follow-up examinations in 2002, and 405 (55%) participated. In models controlling for age and sex, breastfeeding was inversely associated with common carotid intima-media thickness (IMT; difference -0.03 mm; 95% CI, -0.07 to 0.01), bifurcation IMT (difference -0.19 mm; 95% CI, -0.37 to -0.01), carotid plaque (odds ratio [OR], 0.52; 95% CI, 0.29 to 0.92), and femoral plaque (OR, 0.54; 95% CI, 0.26 to 1.12), compared with bottle-feeding. Controlling for socioeconomic variables in childhood and adulthood, smoking and alcohol made little difference to effect estimates. Controlling for factors potentially on the causal pathway (blood pressure, adiposity, cholesterol, insulin resistance, and C-reactive protein) made little difference to observed associations.

CONCLUSIONS

Breastfeeding may be associated with a reduced risk of atherosclerosis in later life. Measurement error and power considerations limit the extent to which conclusions about the mechanisms underlying this relationship can be made.

Breast feeding and cardiovascular disease risk factors, incidence, and mortality: the Caerphilly study

STUDY OBJECTIVE

To investigate the association of having been breast fed with cardiovascular disease risk factors, incidence, and mortality.

DESIGN

Prospective cohort study.

SETTING

Caerphilly, South Wales.

PARTICIPANTS

All men aged 45-59 years living in and around the study area. Of 2818 eligible men, 2512 (89%) were seen. Altogether 1580 men (63%) obtained details of how they had been fed in infancy (ever breast fed or only bottle fed) from their mother or a close female relative. A subset of 1062 subjects reported on whether bottle fed or the duration of breast feeding if breast fed.

MAIN RESULTS

Breast feeding was not associated with stature, blood pressure, insulin resistance, total cholesterol, or fibrinogen. In fully adjusted models (controlling for age, birth order, and social position in childhood and adulthood), breast feeding was associated with greater body mass index than bottle feeding (difference: 0.41 kg/m(2) (95% CI: 0.01 to 0.81). There was a positive association between breast feeding and coronary heart disease mortality (hazard ratio: 1.73; 1.17 to 2.55) and incidence (1.54; 1.17 to 2.04) (fully adjusted models). There was no evidence of a duration-response effect, which might be expected if an adverse effect of breast feeding was causal.

CONCLUSION

These data provide little evidence of a protective influence of breast feeding on cardiovascular disease risk factors, incidence, or mortality. A possible adverse effect of breast feeding on coronary heart disease incidence was observed but may have a number of explanations, including selection and information bias. In view of these limitations, further long term studies with improved measures of infant feeding are required to confirm or refute these findings.

Duration of breast feeding and arterial distensibility in early adult life: population based study

OBJECTIVES

To test the hypothesis that duration of breast feeding is related to changes in vascular function relevant to the development of cardiovascular disease.

DESIGN

Population based observational study.

SETTING

Cambridge.

PARTICIPANTS

331 adults (171 women, 160 men) aged between 20 and 28 years, born in Cambridge Maternity Hospital.

MAIN OUTCOME MEASURES

Distensibility of brachial artery, type and duration of infant feeding, current lipid profile, and other cardiovascular risk factors.

RESULTS

The longer the period of breast feeding the less distensible the artery wall in early adult life, with no sex differences (regression coefficient = -3.93 micrometer/month, 95% confidence interval -7.29 to -0.57, P=0.02). However, in those breast fed for less than four months, arterial distensibility was not significantly reduced compared with an exclusively formula fed group. The vascular changes observed were not explained by alterations in plasma cholesterol concentration in adult life.

CONCLUSIONS

Breast feeding in infancy is related to reduced arterial function 20 years later. These data should not alter current recommendations in favour of breast feeding, which has several benefits for infant health. Further work is needed, however, to explore the optimal duration of breast feeding in relation to cardiovascular outcomes.