Multiple micronutrients showed no clear difference in neonatal mortality compared with control (iron with or without folic acid) (high certainty).
Main comparison (FFN knowledge showed no clear difference in maternal hospitalization compared with no knowledge) (low certainty).
The review found no eligible studies for this question.
It is very uncertain whether vitamin D + calcium supplementation changes low birthweight (less than 2500 g) compared with placebo or no intervention (very low certainty).
It is very uncertain whether vitamin D + calcium + other vitamins and minerals changes gestational diabetes compared with calcium + other vitamins and minerals (but no vitamin D) (very low certainty).
Vitamin D + calcium + other vitamins and minerals showed no clear difference in low birthweight (less than 2500 g) compared with calcium + other vitamins and minerals (but no vitamin D) (low certainty).
Vitamin D supplementation probably leads to lower gestational diabetes compared with placebo or no intervention (moderate certainty).
Vitamin D supplementation may leads to lower maternal adverse events: severe postpartum haemorrhage compared with placebo or no intervention (low certainty).
It is very uncertain whether vitamin D supplementation changes maternal adverse event: nephritic syndrome compared with placebo or no intervention (very low certainty).
Vitamin D supplementation probably leads to lower low birthweight (less than 2500 g) compared with placebo or no intervention (moderate certainty).
It is very uncertain whether vitamin D + calcium supplementation changes gestational diabetes compared with placebo or no intervention (very low certainty).
It is very uncertain whether self‐monitoring at home changes caesarean section compared with hospitalisation (very low certainty).
It is very uncertain whether self‐monitoring at home changes perinatal mortality (stillbirth and neonatal mortality) compared with hospitalisation (very low certainty).
It is very uncertain whether automated telemedicine monitoring changes caesarean section compared with conventional (very low certainty).
Continuous glucose monitoring showed no clear difference in caesarean section compared with intermittent glucose monitoring (moderate certainty).