Intervention in preconception and periconception (vs no intervention, standard of care or routine care, or placebo) | Intervention in preconception and pregnancy (vs intervention in pregnancy only) | |||||||||
Studies | N | Risk Ratio (95% CI) | I2 (%) | Certainty of evidence | Studies | N | Risk ratio (95% CI) | I2 (%) | Certainty of evidence | |
LBW | ||||||||||
Nutrition interventions | ||||||||||
Multiple micronutrient supplementation18 53 64 76 | 4 | 12 054 | 1.06 (0.90 to 1.25) | 0.00 | Low | 0 | 0 | – | – | – |
Iron and folic acid supplementation18 39 47 58 | 3 | 1831 | 0.74 (0.34 to 1.61) | 83.10 | Very low | 1 | 200 | 0.28 (0.08 to 1.03) | – | Very low |
Food supplementation*19 38 43 | 1 | 529 | 0.40 (0.14 to 1.12) | – | Very low | 2 | 1134 | 1.00 (0.79 to 1.26) | 0.00 | Very low |
Other: Calcium supplementation80 | 1 | 507 | 1.00 (0.76 to 1.30) | – | – | 0 | 0 | – | – | – |
Other: Mushroom in diet31 | 1 | 1162 | 0.79 (0.46 to 1.35) | – | – | 0 | 0 | – | – | – |
Health interventions | ||||||||||
General preconception health34 55 | 2 | 1188 | 1.27 (0.83 to 1.94) | 39.11 | Very low | 0 | 0 | – | – | – |
Early adverse pregnancy outcome prevention49 | 1 | 82 | 0.23 (0.11 to 0.51) | – | Very low | 0 | 0 | – | – | – |
NCD interventions (safety)†78 | 0 | 0 | – | – | 1 | 149 | 4.34 (0.55 to 34.34) | – | Very low | |
Infectious disease interventions (safety)†62 79 | 1 | 39 | 4.96 (0.27 to 89.87) | – | Very low | 1 | 186 | 2.65 (1.20 to 5.81) | – | Very low |
SGA | ||||||||||
Nutrition interventions | ||||||||||
Multiple micronutrient supplementation20 | 1 | 1084 | 1.02 (0.74 to 1.40) | – | Very low | 0 | 0 | – | – | – |
Iron and folic acid supplementation18 47 | 2 | 1351 | 0.83 (0.66 to 1.05) | 0.00 | Low | 0 | 0 | – | – | – |
Food supplementation19 43 | 0 | 0 | – | – | – | 2 | 1161 | 0.89 (0.78 to 1.02) | 0.00 | Low |
Health interventions | ||||||||||
General preconception health34 | 1 | 760 | 1.13 (0.57 to 2.14) | – | Very low | 0 | 0 | – | – | – |
Early adverse pregnancy outcome prevention49 88 | 2 | 208 | 0.35 (0.18 to 0.68) | 0.00 | Low | 0 | 0 | – | – | – |
Infectious disease interventions (safety)*72 | 1 | 2871 | 1.23 (0.33 to 4.57) | – | Very low | 0 | 0 | – | – | – |
PTB | ||||||||||
Nutrition interventions | ||||||||||
Multiple micronutrient supplementation18 53 66 76 | 4 | 12 235 | 1.03 (0.90 to 1.18) | 39.04 | Low | 0 | 0 | – | – | – |
Iron and folic acid supplementation18 47 | 2 | 1360 | 1.42 (0.60 to 3.37) | 87.79 | Very low | 0 | 0 | – | – | – |
Food supplementation19 43 | 0 | 0 | – | – | – | 2 | 1163 | 1.38 (1.06 to 1.79) | 0.00 | Very low |
Other: Calcium supplementation80 | 1 | 579 | 0.90 (0.74 to 1.10) | – | – | 0 | 0 | – | – | – |
Other: Mushroom in diet31 | 1 | 1162 | 0.93 (0.63 to 1.38) | – | – | 0 | 0 | – | – | – |
Health interventions | ||||||||||
General preconception health34 | 1 | 786 | 1.41 (0.74 to 2.69) | – | Very low | 0 | 0 | – | – | – |
Early adverse pregnancy outcome prevention49 60 67 73 88 | 5 | 382 | 0.32 (0.20 to 0.51) | 5.13 | Very low | 0 | 0 | – | – | – |
Infectious disease interventions59 70 | 2 | 2275 | 0.62 (0.20 to 1.93) | 95.34 | Very low | 0 | 0 | – | – | – |
Infectious disease interventions (safety†)68 72 74 | 3 | 3666 | 1.05 (0.71 to 1.57) | 0.00 | Very low | 0 | 0 | – | – | – |
Infectious disease interventions (safety‡)71 | 1 | 181 | 0.06 (0.00 to 0.96) | – | Very low | 0 | 0 | – | – | – |
Social interventions | ||||||||||
Reproductive planning54 | 1 | 1140 | 0.79 (0.63 to 0.99) | – | Very low | 0 | 0 | – | – | – |
Certainty of evidence assessed using the GRADE tool.
Some studies included consisted of women with underlying conditions (eg, previous pre-eclampsia or HIV). These are identified in table 1 and figures 3–5.
*The identified study compared the effect of a longer duration of food supplementation with a shorter duration.; the OR is reported for this study as risk ratio could not be computed.
†The aim of interventions was not to prevent LBW, PTB or SGA, and the anticipated effect of interventions was not necessarily protective.
‡The aim of interventions was not to prevent PTB, and the anticipated effect of interventions was not necessarily protective; additionally, the effect estimate of this study could not be statistically combined with that of other studies due to its CI including the null.
GRADE, Grading of Recommendations Assessment, Development and Evaluation; LBW, low birth weight; NCD, non-communicable disease; PTB, preterm birth; SGA, small for gestational age.