In this issue of Pediatrics, Bateman et al1 have elegantly convinced readers that infants of mothers prescribed β-blockers in late pregnancy, in a large American database, have a significantly elevated risk (4.3%) of neonatal hypoglycemia, with an adjusted odds ratio of 1.68. This finding is important because β-blockers are used commonly to treat hypertensive orders in pregnancy, and in Bateman et al’s study >10 000 women, 0.5% of pregnancies, delivering between 2003 and 2007 were exposed to β-blockers at the time of delivery. Their results are physiologically plausible because β-blockers cross the placenta, and the resultant sympathetic blockade could be expected to lead to hypoglycemia, which may be asymptomatic. Screening for hypoglycemia appears to be the natural conclusion. But should we?

The accepted definition of hypoglycemia at the time of this study was a blood glucose level ≤45 mg/dL (≤2.6 mmol/L).2 The authors verified the electronic diagnostic codes...

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