Does metformin treatment for GDM adversely affect offspring?

  • Tarry-Adkins JL & al.
  • PLoS Med
  • 1 ago. 2019

  • de Miriam Tucker
  • Clinical Essentials
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Takeaway

  • Despite lower average birth weight, children whose mothers were treated with metformin for gestational diabetes mellitus (GDM) show accelerated postnatal growth.

Why this matters

  • Patterns of low birth weight and postnatal catch-up growth have been linked to adverse long-term cardiometabolic outcomes.
  • Metformin is increasingly used for GDM as a cheaper alternative to insulin.

Study design

  • Meta-analysis of 28 studies including 3976 mothers randomly assigned to metformin or insulin for GDM treatment with reported offspring outcomes.
  • Funding: author funding from the British Heart Foundation, Medical Research Council.

Key results

  • Neonates born to metformin-treated mothers weighed 107.7 g less than those of insulin-treated mothers (P=.005) and were 40% less likely to have macrosomia (OR, 0.59; P<.001>
  • At ages 18 months-2 years, children of metformin-treated mothers weighed 440 g more than those of insulin-treated mothers (P=.03).
  • At ages 5-9 years, BMI was 0.78 kg/m2 higher in metformin vs insulin group (P=.005).
  • No height differences.

Limitations

  • Only 2 studies followed up to midchildhood.
  • Possible recall bias with later follow-up.  
  • Uncertainty about whether lower birth weight represents lower lean mass or fetal adiposity.
  • Bias risk in many studies.
  • Women who required both metformin and insulin usually excluded, potentially skewing results.  
  • Heterogeneity across study GDM criteria.