Association of maternal hypoglycemia with low birth weight and low placental weight: a retrospective investigation.

Abstract

The effects of maternal hypoglycemia on birth weight, placental weight, and placental ratio are unclear. A reliable indicator for increased risk of low birth weight or associated low placental weight could prove invaluable in caring for newborns who are small for gestational age. To retrospectively review 2 years of hospital obstetric records for evidence of an association between maternal hypoglycemia (< fifth percentile at 24-week 1-hour glucose challenge test) and birth weight, placental weight, or placental ratio. Medical center records were reviewed for women who delivered a term newborn between July 1, 2005, and July 31, 2007. Women included in the study were younger than 35 years and had completed a 1-hour glucose challenge test during pregnancy. Excluded were women with comorbid conditions that may be associated with abnormal birth weight and women with serum glucose levels greater than 135 mg/dL. Newborns of women with hypoglycemia weighed, on average, significantly less than newborns of women with normal blood glucose levels (t test P=.011). Relative risk was 5.81 (95% confidence interval, 1.25-27.03). Placentas of women with hypoglycemia were also lighter than those of the women in the control group, but the difference was not significant (t test P=.1089). Differences in placental ratios between the 2 groups were not statistically significant (P=.8171). Lower serum glucose levels during pregnancy might be a causative factor, rather than merely a risk factor, for lower birth weights.