Hypoglycemia in term newborns with a birth weight below the 10th percentile

Current recommendations suggest that routine screening for hypoglycemia should be performed in all term newborns with a birth weight (BW) below the 10th percentile. The impact of updated growth curves on the incidence of hypoglycemia in small-for-gestational-age (SGA) newborns has not been evaluated.

To evaluate the occurrence and severity of hypoglycemia in term newborns with a BW between the 10th and fifth percentile, and below the fifth percentile, using recently updated growth curves.

A one-year prospective cohort study.

Inclusion criteria were gestational age of 37 weeks or greater and BW below the 10th percentile. Neonatal hypoglycemia was defined as a blood glucose level of less than 2.6 mmol/L measured after 2 h of life. Blood glucose was measured routinely for all SGA infants during the first 36 h of life.

A total of 187 SGA infants met the study criteria: 85 infants with a BW between the 10th and fifth percentile, and 102 infants with a BW below the fifth percentile. The characteristics of the study cohort were similar between BW groups. Twenty-six per cent of the infants screened had at least one episode of hypoglycemia: 22% of infants in the 10th to fifth percentile group and 28% in the less than fifth percentile group. Hypoglycemia was symptomatic in four infants, all of whom were below the fifth percentile for BW. The mean (± SD) lowest blood glucose level was 2.1±0.4 mmol/L (range 0.6 mmol/L to 2.5 mmol/L) in the 10th to fifth percentile group and 2.0±0.5 mmol/L (range 0.8 mmol/L to 2.5 mmol/L) in the less than fifth percentile group (P=0.05).

The present study demonstrates a high incidence of hypoglycemia among SGA infants with a BW below the 10th percentile using updated growth curves. There was no difference in the incidence of hypoglycemia among SGA infants with a BW below the fifth percentile versus those with a BW between the 10th and fifth percentile.