Researchers discover that rate of weight gain in midpregnancy affects the infant’s body mass differently than weight gain during late pregnancy….
Estampador, AC. et al. designed a study to determine the relationship between maternal weight gain and infant body fat composition, plasma glucose, and insulin concentrations at 4 months of age. They also studied the role of the adipokines IL-6, leptin, and adiponectin in mediating the above relationships, because these hormones are already known to play a role in adult obesity and diabetes.
A total of 32 pregnant women from north Sweden participated in this study. Gestational data was obtained during study visits at the Clinical Research Center at Umeå University hospital when the women reached 28-32 weeks. Data recorded for the mothers included: height, weight, BMI, body composition, total body water, and fat-free mass. Data was also taken from the mother’s medical records at weeks 8-16 and 36-41 to assess changes in BMI and weight gain. Infants were assessed at a mean age of 4.25 months, with the following data recorded: body length, weight, fat mass and fat-free mass. A venous blood sample was taken from the back of the infant’s hand after at least 2h without feeding to determine serum IL-6 concentrations, plasma leptin, plasma adiponectin, serum glucose levels and serum insulin levels.
Infant birth weight was found to be positively correlated with late pregnancy weight gain. Furthermore, infant birth weight was strongly correlated with infant fat-free mass at 4 months. Infant fat-free mass was then positively correlated with infant glucose adjusted for insulin. Maternal adiposity, determined by BMI and fat mass, was strongly inversely correlated with IL-6 concentrations in the infant. This result was somewhat surprising as previous studies using fetal cord blood showed higher IL-6 concentrations in obese mothers. Infant fat-free mass was inversely related to infant adiponectin concentrations. No significant associations were found for leptin concentrations.
Maternal obesity and glucose concentrations in pregnancy are known to increase the risk of T2DM in the offspring, with obesity in the offspring thought to be an important mediating factor. This study had a novel finding in its discovery that rate of gestational weight gain at different periods in pregnancy is differentially associated with infant body composition at 4 months. More specifically, rate of weight gain in midpregnancy is associated with infant fat mass, and rate of weight gain in late pregnancy is associated with infant fat-free mass. The association of midpregnancy weight gain with infant fat mass is supported by a previous study on prenatal fat development that shows gestational age between 14 and 29 weeks being the critical time frame for determining adipogenesis. Histological evidence also showed that adipose tissue differentiation occurs between the 14th and 16th weeks, followed by fat-cell proliferation until the 23rd week, after which the existing fat lobules increase in size but not in number. A previous study by Davenport, et al. had similar findings, showing that weight gain in the first half of pregnancy is related to greater adiposity in the infant at birth.
The current study shows that this effect is still evident at 4 months of age. Further research, however, is needed to determine how the associations between maternal characteristics and infant adipokines are involved in the relationship between maternal gestational weight gain and infant body composition.
- Rate of weight gain in midpregnancy was associated with infant fat mass, whereas rate of weight gain in late pregnancy was associated with infant fat-free mass.
- Maternal adiposity was inversely related to infant IL-6 concentrations. Infant fat free mass was also inversely related to infant adiponectin concentrations, and positively related to glucose adjusted for insulin. These findings suggest that leaner infants may be less sensitive to insulin.
Estampador, AC. et al. "Infant Body Composition and Adipokine Concentrations in Relation to Maternal Gestational Weight Gain" Diabetes Care. 2014; 38: 7p.