The Impact of Preconception Maternal BMI on Child Obesity

Prepregnancy maternal obesity is associated with a significantly increased risk for child obesity, according to the results of a systematic review and meta-analysis published in PLOS Medicine.

While the importance of preventing childhood obesity is well known, the results of interventions to date have been disappointing. The goal of this study was to assess the dose-response association between maternal preconception body mass index (BMI) and the risk for obesity in offspring.

The systematic review included 79 studies, including 56 prospective studies (sample size ranging between 70 and 100,612 participants). Most studies (32) were from the United States and all were rated as medium- or high-quality.

The primary outcome was child obesity (BMI ≥95th percentile). The results of meta-analysis of 20 studies (12,475 cases of obesity in 88,872 children age 1 to 14 years) indicated the odds ratio (OR) for each 5 kg/m² increase in maternal BMI was 1.70 (95% CI, 1.55-1.87).

Secondary outcomes included child overweight or obesity (BMI ≥85th percentile) and child overweight (BMI in the 85th to 95th percentile). There were 22 studies included for meta-analysis (181,800 children age 1 to 16 years, including 31,328 overweight or obese children) to assess the association of maternal preconception BMI with the risk for child overweight or obesity. The odds ratio (OR) for each 5 kg/m² increase in maternal BMI was 1.55 (95% CI, 1.43-1.69) for child overweight or obesity. For child overweight, data from 10 studies were pooled (53,238 children age 1 to 11 years, including 10,491 overweight children) and researchers found that the odds ratio for each 5 kg/m² increase in maternal BMI was 1.30 (95% CI, 1.13-1.50).

Assuming nonlinear associations, maternal obesity was associated with an increased risk for child obesity (OR, 3.64; 95% CI, 2.68-4.95), child overweight (OR, 1.80; 95% CI, 1.25-2.59), and child overweight or obesity (OR, 2.69; 95% CI, 2.10-3.46). Maternal overweight was also associated with increased risk for child obesity (OR, 1.89; 95% CI, 1.62-2.19), child overweight (OR, 1.41; 95% CI, 1.19-1.67), and child overweight or obesity (OR, 1.65; 95% CI, 1.47-1.85). Meta-regression found increasing odds of child obesity with increasing child age.

The researchers acknowledged some study limitations, including that inclusion criteria restricted studies to only those published in English and limited data from low- and middle-income countries. Furthermore, the included studies did not always report the data in a format that enabled inclusion in the meta-analysis.

“This systematic review and meta-analysis identified significantly increased odds of child obesity when mothers have obesity before conception,” wrote the researchers.

“This research adds to the substantial evidence base that the causes of obesity involve a complex interplay between in utero and life course exposures, which may unequally affect those with a predisposition to obesity,” they concluded.

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Reference

Heslehurst N, Vieira R, Akhter Z, et al. The association between maternal body mass index and child obesity: A systematic review and meta-analysis [published online June 11, 2019]. PLoS Med. doi:10.1371/journal.pmed.1002817