Maternal Weight Gain Is Associated With Infant Insulin Concentrations During the 1st Year of Life
- Address correspondence to Carol S. Johnston, PhD, Department of Nutrition, Arizona State University, 7001 East Williams Field Rd., Mesa, AZ 85212. E-mail: carol.johnston{at}asu.edu
Since hyperinsulinemia tracks from childhood to adulthood and is associated with diabetes risk, identifying modifiable conditions during gestation that may impact insulin metabolism in offspring is important. We conducted a pilot study to investigate associations between maternal weight gain and infant insulin concentrations in an underserved population at high risk for diabetes. Mexican or Native American women with an infant <1 year of age provided written consent. Infant weight-for-age Z scores (WAZ) were calculated, and nonfasting plasma samples were analyzed for insulin by standard assay. Pearson’s bivariate test was used to assess relationships between variables, and the unpaired t test was used to examine differences between means.
A total of 16 women ([means ± SE] 21.8 ± 1.7 years) and their infants (6.4 ± 0.9 months; 9 males and 7 females) completed the study, and medical records were available for 9 of these pairs. Based on combined self-reports and medical records, the mean prepregnancy weight was 71.5 ± 4.0 kg, and the mean pregnancy weight gain was 10.7 ± 2.4 kg. Infants were full term with birth weights ranging from 2,495 to 4,309 g (3,381 ± 121.0 g); WAZ scores averaged 0.47 ± 0.23. Blood insulin concentrations averaged 11.5 ± 1.6 mU/l. Gestational weight gain was significantly correlated to infant insulin concentrations (r = 0.662; P = 0.005); however, for nondiabetic women with verifiable pregnancy weight gain (n = 8), this association was strengthened (r = 0.763, P = 0.028; Fig. 1). Infant insulin concentrations (n = 16) were not associated with birth weight, infant age, WAZ scores, prepregnancy weight, or maternal age.
These data show that maternal weight gain predicted infant insulin concentrations, explaining nearly 60% of the variance in these values. Diabetes during pregnancy has been associated with cord blood insulin and with insulin concentrations in adolescence (1), and in nondiabetic pregnancies, maternal weight gain was related to cord blood insulin in macrosomic neonates (2). Currently, a weight gain of 6.8–11.5 kg is recommended for overweight women, and obese women are advised to gain a minimum of 6.8 kg. In obese, nondiabetic women, minimal gestational weight gain (<5 kg) normalized obstetric outcomes, including hypertension, cesarean section, induction of labor, and macrosomia, and did not adversely affect fetal outcomes (3). Utilizing an emerging obstetric outcome, infant insulin concentrations, our preliminary data support the contention that gestational weight gain should be carefully considered in overweight populations at high risk for diabetes. Differential analyses of our data show that minimal gestational weight gain in the nondiabetic women (≤5 vs. >5 kg) was associated with lower infant insulin concentrations (7.2 ± 0.6 vs. 13.4 ± 2.0 mU/l; P = 0.013). Together, the available data indicate that controlling weight gain during obese pregnancies may be advantageous and that more studies of this nature are warranted.
Correlation of maternal weight gain and infant insulin concentrations (n = 8 mother/infant pairs; r = 0.763, P = 0.028).
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