Inter-generational link of obesity in term and preterm births: role of maternal plasma acylcarnitines

Background/objectives Acylcarnitines, intermediates of fatty acid oxidation, are known to be involved in obesity and insulin resistance. Since maternal prepregnancy overweight or obesity (OWO) is a recognized major risk factor for offspring OWO, we hypothesized that maternal plasma acylcarnitines may play a role in inter-generational OWO. Subjects/methods This study included 1402 mother-child pairs (1043 term, 359 preterm) recruited at birth from 1998-2013 and followed prospectively up to age 18 years at the Boston Medical Center. The primary outcomes were child OWO defined as BMI >= 85th percentile for age and sex. The primary exposures were maternal prepregnancy OWO defined as BMI >= 25 kg/m(2) and maternal acylcarnitine levels measured in plasma samples collected soon after delivery using liquid chromatography-tandem mass spectrometry (LC-MS) in a targeted manner. Results Approximately 40% of the children in this study were OWO by age 5. Maternal OWO had a significant association with childhood OWO, both in term and preterm births. beta-hydroxybutyryl-carnitine (C4-OH) levels were significantly and positively associated with child OWO among term births after adjustment for potential confounders and multiple-comparisons. Children born to OWO mothers in the top tertile C4-OH levels were at the highest risk of OWO: OR = 3.78 (95%CI: 2.47, 5.79) as compared with those born to non-OWO mothers in the lowest tertile (P for interaction of maternal OWO and C4-OH = 0.035). In a four-way decomposition of mediation/interaction analysis, we estimated that C4-OH levels explained about 27% (se = 0.08) of inter-generational OWO risk (P = 0.001) . In contrast, these associations were not observed in preterm births. Conclusions In this U.S. urban low-income birth cohort, we provide further evidence of the inter-generational link of OWO and reveal the differential role of C4-OH in explaining the inter-generational obesity between term and preterm births. Further investigations are warranted to better understand and prevent the inter-generational transmission of OWO.