Impact of Maternal Metabolic Parameters on Birth Weight and Cord Blood Insulin Concentration—Findings from the Born in Guangzhou Study

Objective: To investigate the relationship between maternal metabolic parameters with birth weight (BW) and cord blood insulin level(CBI).

Research Design and Methods: Participants were mother-baby pairs (n=1,522) from the Born in Guangzhou Cohort Study (delivered during January 2015 to June 2016). Data on maternal pre-pregnancy BMI, Gestational Weight Gain (GWG), mid-pregnancy fasting glucose and lipid levels were collected; and associations with new-born BW and CBI (z-score) were assessed using multivariable linear regression model, controlling for maternal age, ethnic group, parity and early pregnancy cigarettes exposure. The effect estimates (Regression Co-Efficient: RCE) were standardised to compare the strength of associations of the exposures on BW and CBI z-score.

Results: Z-scores for pre-pregnancy BMI (RCE: 0.20[95% CI: 0.15, 0.24]), early GWG (RCE: 0.18[95% CI: 0.13, 0.23]), glucose (RCE: 0.08[95% CI: 0.04, 0.12]) and triglycerides (RCE: 0.12[95% CI: 0.08, 0.16])) were positively associated with BW z-score. Similar associations were observed with CBI z-score (pre-pregnancy BMI (RCE: 0.11[95% CI: 0.06, 0.16]), early GWG (RCE: 0.07[95% CI: 0.00, 0.13]), glucose (RCE: 0.14[95% CI: 0.09, 0.19]) and triglycerides (RCE: 0.07[95% CI: 0.02, 0.12]). Maternal fasting high-density lipoprotein was negatively associated with BW z-score (RCE:-0.04[95% CI:-0.09, -0.00]) and CBI z-score (RCE: -0.04[95% CI:-0.09, 0.01]) but the 95% CI for the latter included the null.

Conclusions: Maternal pre-pregnancy BMI had the strongest association with BW and CBI, emphasising the importance of optimising preconception BMI. Our results also suggest potential under-recognised adverse effects of intrauterine exposure to gestational dyslipidaemia and that this may warrant clinical attention.