Comparison 1. Preconception lifestyle advice on a combination of any of the following topics: weight, diet, vitamin and mineral intake, alcohol intake, caffeine intake, physical activity, smoking, and/or other substance abuse vs routine care or attention control.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1.1 Live birth	1		Risk Ratio (M‐H, Random, 95% CI)	Totals not selected
1.2 Reported behavioural changes in weight: BMI	1		Mean Difference (IV, Random, 95% CI)	Totals not selected
1.3 Reported behavioural changes in diet: vegetable intake	1		Mean Difference (IV, Random, 95% CI)	Totals not selected
1.4 Reported behavioural changes in vitamin and mineral supplement intake: use of folic acid supplement	2	850	Risk Ratio (M‐H, Random, 95% CI)	0.98 [0.95, 1.01]
1.5 Reported behavioural changes in alcohol intake: numbers of women and men abstaining from alcohol	1		Risk Ratio (M‐H, Random, 95% CI)	Totals not selected
1.5.1 Number of women abstaining from alcohol	1		Risk Ratio (M‐H, Random, 95% CI)	Totals not selected
1.5.2 Number of men abstaining from alcohol	1		Risk Ratio (M‐H, Random, 95% CI)	Totals not selected
1.6 Reported behavioural changes in smoking: numbers of women and men not smoking	1		Risk Ratio (M‐H, Random, 95% CI)	Totals not selected
1.6.1 Number of women not smoking	1		Risk Ratio (M‐H, Random, 95% CI)	Totals not selected
1.6.2 Number of men not smoking	1		Risk Ratio (M‐H, Random, 95% CI)	Totals not selected
1.7 Clinical pregnancy	2		Risk Ratio (M‐H, Random, 95% CI)	Totals not selected