Table 1.

Criteria for the selection of studies

Inclusion	Exclusion
Studies that reported any pregnancy, neonatal or infant outcomes in preconception or pregnant women, any age, weight or body mass index, without date limits.	Health conditions that may influence dietary intake (i.e. unrepresentative sample such as gestational diabetes).
At least three randomised controlled trials per outcome.	Studies published in languages other than English.
Any healthy, human population.	Studies in animals.
Randomised or pseudo‐randomised controlled trials on dietary interventions, including counselling, food and/or both provided by any health professional.	Case study, editorial, conference proceeding.
Any intensity, frequency or timing of intervention.	Studies on gestational weight gain.
Positive or neutral methodological quality.*	Trials solely on nutrient supplementation (i.e. tablet form; no macronutrient change).
	Multiple births.
	Duplicate populations (the data reporting the smaller number of participants for the same pregnancy outcome was excluded).
	Negative methodological quality.*

*American Dietetic Association Quality Criteria Checklist for Primary Research (see Academy of Nutrition and Dietetics 2012).