Maternal Hyperglycemia is not the Only Cause of Macrosomia: Lessons Learned from the Nonobese Diabetic Mouse

ABSTRACT

Maternal hyperglycemia has been implicated as the major cause of neonatal macro-somia, yet clinicians frequently report the birth of large-for-gestational-age infants in normoglycemic pregnancies. We examined the relationship between birthweight, maternal blood glucose (BG), glycosylated hemoglobin (GHb) levels, litter size, maternal age, gestational duration, and parity using the non-obese diabetic (NOD) mouse model. We observed 133 litters and analyzed the birthweight in relation to BG, GHb, litter size, maternal age, gestational duration, and parity. We found that mean litter birthweight was significantly negatively correlated with the total number of pups in each litter (r = -0.39; P <0.01) and significantly positively correlated with parity (r = 0.19; P <0.05) and maternal age (r = 0.22; P <0.05). The total number of pups was significantly negatively correlated with parity (r = -0.33; P <0.01) and with parentage (r = -0.21; P <0.05). The relationship between birthweight and GHb was bimodal. No relationship was found with a GHb less than 2.5%, a significant positive correlation was found for GHb between 2.6% and 4.0% (r = 0.67; P <0.01), and a negative relationship was found when GHb was above 4.0%. Thus, increased parity, maternal age and glucose are associated with increased birthweight. Mild hyperglycemia plays the major role when age, maternal size, gestational duration, and parity are controlled.