For birth weight, a fetal genetic score can affect fetal growth at various levels of maternal fasting plasma glucose (FPG) and is independent of maternal glycemia, according to a study published in Diabetes.
Alice E. Hughes, of the Institute of Biomedical and Clinical Science, University of Exeter Medical School, in Exeter, UK, and associates conducted a genetic and statistical analysis to understand the interactions between fetal genotype and maternal glycemia and insulin-mediated growth.
The authors used data from the Exeter Family Study (2051 mother/offspring pairs) of Childhood Health and the Hyperglycemia and Adverse Pregnancy Outcome study (2842 mother/offspring pairs) to examine the influences that maternal fasting plasma may have on birth weight and fetal insulin.
The investigators reported that birth weight was affected by the fetal genetic score independent of maternal FPG; the fetal genetic score influenced all maternal glycemia levels.
For offspring with the highest and lowest tertile genetic scores—with mothers with FPG in the top tertile—the frequency of being large for gestational age (birth weights equal or greater than 90th percentile) was 31.1% and 14.0%, respectively. These results were similar for both study groups.
In contrast to maternal glucose, the fetal genetic score did not affect the cord insulin or C-peptide.
“This work demonstrates that for any level of maternal FPG, fetal genetics has a major impact on fetal growth and acts predominantly through independent mechanisms,” the authors concluded.
Hughes AE, Nodzenski M, Beaumont RN, et al. Fetal genotype and maternal glucose have independent and additive effects on birth weight. Diabetes. 2018;67:1024–1029