Summary of findings 2. Preconception lifestyle advice on weight compared to routine care or attention control for people with infertility and obesity.
| Preconception lifestyle advice on weight compared to routine care or attention control for people with infertility and obesity | ||||||
| Patient or population: women with infertility and obesity Setting: university/hospital Intervention: preconception lifestyle advice on weight Comparison: routine care | ||||||
| Outcomes | Anticipated absolute effects* (95% CI) | Relative effect (95% CI) | №. of participants (studies) | Certainty of the evidence (GRADE) | Comments | |
| Risk with routine care or attention control | Risk with preconception lifestyle advice on weight | |||||
| Live birth | 494 per 1000 | 465 per 1000 (306 to 707) | RR 0.94 (0.62 to 1.43) | 707 (2 RCTs) | ⊕⊝⊝⊝ VERY LOWa,b,c,d | Evidence about the effect on live birth of preconception lifestyle advice on weight is very uncertain |
| Adverse events ‐ Hypertension | 162 per 1000 | 173 per 1000 (107 to 283) | RR 1.07 (0.66 to 1.75) | 317 (1 RCT) | ⊕⊝⊝⊝ VERY LOWa,c,e | Evidence about the effect on hypertension of preconception lifestyle advice on weight is very uncertain |
| Adverse events ‐ Gestational diabetes | 198 per 1000 | 154 per 1000 (95 to 249) | RR 0.78 (0.48 to 1.26) | 317 (1 RCT) | ⊕⊝⊝⊝ VERY LOWa,c,e | Evidence about the effect on gestational diabetes of preconception lifestyle advice on weight is very uncertain |
| Miscarriage | 94 per 1000 | 141 per 1000 (89 to 223) | RR 1.50 (0.95 to 2.37) | 577 (1 RCT) | ⊕⊝⊝⊝ VERY LOWa,c,d | Evidence about the effect on miscarriage of preconception lifestyle advice on weight is very uncertain |
| Reported behavioural changes in weight: BMI (measured at 6 months) | Mean reported behavioural changes in weight: BMI was 35.6 kg/m² | MD 1.3 kg/m² lower (1.58 lower to 1.02 lower) | ‐ | 574 (1 RCT) | ⊕⊕⊝⊝ LOWa,c | Preconception lifestyle advice on weight may result in a slight reduction in BMI |
| Reported behavioural changes in weight: percentage of weight loss (measured at 6 months) | Mean reported behavioural changes in weight: percentage of weight loss was ‐0.97% | MD 3.29 % lower (4.34 lower to 2.24 lower) | ‐ | 380 (2 RCTs) | ⊕⊝⊝⊝ VERY LOWa,c,d | Evidence about the effect on percentage of weight loss of preconception lifestyle advice on weight is very uncertain |
| Reported behavioural changes in diet: vegetable intake assessed with FFQ (measured at 6 months) | Mean reported behavioural changes in diet: vegetable intake was 128.75 grams/d | MD 0 grams/d (4.18 lower to 4.18 higher) | ‐ | 250 (1 RCT) | ⊕⊝⊝⊝ VERY LOWc,d,f | Evidence about the effect on vegetable intake of preconception lifestyle advice on weight is very uncertain |
| Reported behavioural changes in diet: fruit intake assessed with FFQ (measured at 6 months) | Mean reported behavioural changes in diet: fruit intake was 135.75 grams/d | MD 7.25 g/day lower (7.86 lower to 6.64 lower) | ‐ | 258 (1 RCT) | ⊕⊝⊝⊝ VERY LOWc,d,f | Evidence about the effect on fruit intake of preconception lifestyle advice on weight is very uncertain |
| Reported behavioural changes in alcohol intake assessed with FFQ (measured at 6 months) | Mean reported behavioural change in alcohol consumption was 0 glasses/d | MD 0 glasses/d (0 to 0 ) | ‐ | 239 (1 RCT) | ⊕⊝⊝⊝ VERY LOWc,d,f | Not estimable |
| Reported behavioural changes in physical activity assessed with SQUASH (measured at 6 months) | Mean reported behavioural change in physical activity was 361.24 minutes/week | MD 50.76 minutes/week higher (16.77 higher to 84.75 higher) | ‐ | 254 (1 RCT) | ⊕⊝⊝⊝ VERY LOWc,d,f | Evidence about the effect on physical activity of preconception lifestyle advice on weight is very uncertain |
| *The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; FFQ: Food Frequency Questionnaire; MD: mean difference; RCT: randomised controlled trial; RR: risk ratio. | ||||||
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GRADE Working Group grades of evidence. High quality: further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: we are very uncertain about the estimate. | ||||||
aDowngraded by one level for serious risk of bias: high risk for performance bias.
bDowngraded by one level for serious inconsistency: substantial heterogeneity (I² = 68%) and wide variance of point estimates across studies with opposite directions of effect.
cDowngraded by one level for serious indirectness: differences in comparison (access to fertility treatment). Specific population: women with infertility and obesity.
dDowngraded by one level for serious imprecision: < 400 events and 95% CIs overlap.
eDowngraded by two levels for very serious imprecision: one study, few events (< 400) and 95% CIs include important benefit and harm.
fDowngraded by one level for serious risk of bias: high risk for performance and detection bias.