Children whose mothers smoked or were overweight before becoming pregnant were likely to become overweight in childhood, researchers found.

Maternal prepregnancy smoking status was associated with a 47% increased odds of childhood overweight (aOR 1.47, 95% CI 1.26 to 1.73), according to Cristine Glazebrook, PhD, of the University of Nottingham Innovation Park in England, and colleagues.

Mothers who were overweight before giving birth also were significantly more likely to have children who were overweight at age 3 (aOR 1.37, 95% CI 1.18 to 1.58), age 7 (aOR 4.25, 95% CI 2.86 to 6.32), and ages 9 to 14 (aOR 2.36, 95% CI 2.36 to 8.85), they wrote online in BMJ.

The authors also noted that there was a “moderate protective effect of ever breastfeeding during the first year on subsequent childhood overweight,” as well as “some evidence that the early introduction of solid foods was associated with childhood overweight.”

The researchers looked at risk factors for childhood overweight that could be pinpointed during the child’s first year through a systematic review and meta-analysis of 30 prospective studies that followed children from birth to at least 2 years old and up to 16 years old.

In addition to the risks of maternal overweight and smoking status, high birth weight and rapid weight gain after birth were significantly associated with childhood overweight.

Among six of seven studies evaluating birth weight with childhood overweight, weights as low as 8.5 lbs. (3.86 kg) or greater (aOR 2.17, 95% CI 1.22 to 3.87) and as high as 9.4. lbs. (4.25 kg) or greater (aOR 2.17, 95% CI 1.83 to 2.59) were significantly associated with overweight at childhood from ages 3 to 7.

Among studies looking at the relationship between infants who gained weight the quickest versus the slowest and childhood overweight, infants who gained weight the quickest were significantly more likely to be overweight by childhood. One study showed a nearly four-fold increased odds of overweight status by age 4.5 years for those who gained weight fastest during childhood (aOR 3.9, 95% CI 1.9 to 7.9), while another showed more than a 50% increased odds of overweight status in children ages 9 to 14 among infants who gained weight the fastest (aOR 1.63, 95% CI 1.05 to 2.53).

Infants fed solids before 4 months were also significantly more likely to be overweight by age 3, with 12% increased odds (aOR 1.12, 95% CI 1.02 to 1.23), and, in a population of formula-fed infants, a 6.3-fold increased risk (aOR 6.3, 95% CI 2.3 to 16.9).

The researchers also noted that breastfeeding appeared to offer a protective effect against childhood overweight. Mothers who had ever breastfed their infants had children with a 15% reduced risk of overweight (aOR 0.85, 95% CI 0.74 to 0.99).

The authors said the findings “could be used to develop screening guidelines or checklists for healthcare professionals for identifying infants at greatest risk” for overweight in childhood. They added that most of the risks were nonmodifiable, but that the modifiable factors “could be explored further with a contemporary cohort of children.”

The analysis was limited by the late cut-off age, variety of socioeconomic backgrounds of participants, heterogeneity of outcomes, and publication biases in smoking-related studies.

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Primary source: Archives of Disease in Childhood
Source reference: Glazebrook CP, et al “Systematic review and meta-analysis of risk factors for childhood overweight identifiable during infancy” Arch Dis Child 2012; DOI: 10.1136/archdischild-2012-302263.