Dietary advice showed no clear difference in mortality compared with oral nutritional supplements (low certainty).
Dietary advice showed no clear difference in number of people admitted or re‐admitted to hospital compared with oral nutritional supplements (low certainty).
Dietary advice plus supplements if required showed no clear difference in mortality compared with no advice (low certainty).
Dietary advice plus supplements if required showed no clear difference in number of people admitted or re‐admitted to hospital compared with no advice (moderate certainty).
Dietary advice plus supplements if required showed no clear difference in complications compared with no advice (low certainty).
It is very uncertain whether dietary advice interventions changes gestational diabetes compared with standard care (maternal outcomes) (very low certainty).
Dietary advice interventions showed no clear difference in childhood/adulthood adiposity: skinfold thickness at 6 months (mm) compared with standard care (child outcomes) (low certainty).
Dietary advice interventions may leads to lower hypertensive disorders of pregnancy (pregnancy‐induced hypertension) compared with standard care (maternal outcomes) (low certainty).
Dietary advice interventions showed no clear difference in hypertensive disorders of pregnancy (pre‐eclampsia) compared with standard care (maternal outcomes) (low certainty).
Dietary advice interventions showed no clear difference in caesarean section compared with standard care (maternal outcomes) (low certainty).
It is very uncertain whether dietary advice interventions changes perineal trauma (anal sphincter injury) compared with standard care (maternal outcomes) (very low certainty).
Dietary advice interventions showed no clear difference in gestational weight gain (kg) compared with standard care (maternal outcomes) (low certainty).