What do systematic reviews say?

Probiotics vs placebo

Probiotic showed no clear difference in large‐for‐gestational age > 90 centile compared with placebo (low certainty).

• Probiotic treatment for women with gestational diabetes to improve maternal and infant health and well‐being 2020 · Cochrane Headline outcomes only
  RR 0.73 [0.35, 1.52]
  2 studies · 174 participants
  Low

Insulin vs anti‐diabetic agent

Insulin showed no clear difference in large‐for‐gestational age (birthweight > 90th centile) compared with anti‐diabetic agent (moderate certainty).

• Insulin for the treatment of women with gestational diabetes 2017 · Cochrane Headline outcomes only
  RR 1.01 [0.76, 1.35]
  13 studies · 2352 participants
  Moderate

Tight vs moderate glycaemic control (infant outcomes)

• Different intensities of glycaemic control for pregnant women with pre‐existing diabetes 2016 · Cochrane Headline outcomes only
  no estimate extracted
  1 study · 45 participants
  Very low

Tight‐moderate vs loose glycaemic control (infant outcomes)

Tight‐moderate may leads to lower large‐for‐gestational age (birthweight > 90th centile) compared with loose glycaemic control (infant outcomes) (low certainty).

• Different intensities of glycaemic control for pregnant women with pre‐existing diabetes 2016 · Cochrane Headline outcomes only
  RR 0.01 [0, 0.2]
  1 study · 60 participants
  Low

Metformin vs placebo

Metformin showed no clear difference in large‐for‐gestational‐age infant, defined as birthweight ≥ 90th… compared with placebo (high certainty).

• Metformin for women who are overweight or obese during pregnancy for improving maternal and infant outcomes 2018 · Cochrane Headline outcomes only
  RR 0.95 [0.7, 1.3]
  2 studies · 831 participants
  High