To assess the effectiveness and safety of pharmacological and non-pharmacological strategies compared with each other, placebo, or no treatment for weight reduction in obese women with subfertility.
Background
To prevent the adverse effects of obesity, weight loss is recommended as the first line of treatment for obese women seeking pregnancy. The effectiveness of pharmacological and non-pharmacological interventions for obese women with subfertility is unclear.
Study characteristics
We found 10 randomised trials comparing pharmacological and non-pharmacological strategies in 1490 obese women with subfertility.
Key results
Lack of data is a major concern in interpretation of these data. Only 10 studies were included in the analysis. Three studies compared non-pharmacological intervention versus no intervention or placebo. We are uncertain whether diet versus no intervention improves live birth, ongoing pregnancy, clinical pregnancy, or adverse events . A diet or lifestyle intervention may result in body mass index (BMI) weight change. Evidence was insufficient to show a difference in waist-to-hip ratio (WHR) with diet or lifestyle change compared to no intervention. No study reported on quality of life, or mental health outcomes for this comparison.
One study compared non-pharmacological interventions - intensive weight loss intervention versus standard of care nutrition counselling; however due to the very low quality of evidence, we are uncertain whether intensive weight loss interventions improve live birth, clinical pregnancy, quality of life, or mental health outcomes. No study reported on adverse events, or weight changes, for this comparison.
Three studies reported on pharmacological versus pharmacological interventions. Evidence was insufficient to show a difference in adverse events between metformin compared to metformin plus liraglutide. Evidence was insufficient to demonstrate a difference between the combination of metformin, clomiphene, and L-carnitine versus metformin, clomiphene, and placebo for miscarriage . Evidence was insufficient to reveal a difference between the combination of metformin, clomiphene, and L-carnitine versus metformin, clomiphene, and placebo or metformin plus liraglutide versus metformin in clinical pregnancy. Evidence was insufficient to demonstrate a difference between the combination of metformin, clomiphene, and L-carnitine versus metformin, clomiphene, and placebo for weight change using BMI. Moreover, evidence was insufficient to reveal a difference between dexfenfluramine versus placebo or metformin plus liraglutide versus metformin for weight loss in kilograms, or per cent of total body fat. No study reported on live birth and change in quality of life or mental health outcomes for this comparison.
In the comparison of pharmacological intervention versus no intervention or placebo, three studies were included. Evidence was insufficient to show a difference between metformin and control groups related to live birth. Evidence was insufficient to reveal a difference between metformin compared to placebo in live birth, clinical pregnancy, or adverse events. Evidence was insufficient to demonstrate a difference between diet combined with metformin versus diet combined with placebo for weight change using BMI or WHR. No study reported on quality of life or mental health outcomes for this comparison.
We found no study comparing non-pharmacological with pharmacological interventions.
Quality of the evidence
The evidence was of very low to low quality. The main limitations were due to lack of studies and poor reporting of study methods. The main reasons for downgrading of evidence were lack of details by which to judge risk of bias (randomisation and allocation concealment), lack of blinding, and imprecision.
Evidence is insufficient to support the use of pharmacological and non-pharmacological strategies for obese women with subfertility. No data are available for the comparison of pharmacological versus non-pharmacological strategies. We are uncertain whether pharmacological or non-pharmacological strategies effect live birth, ongoing pregnancy, adverse events, clinical pregnancy, quality of life, or mental health outcomes. However, for obese women with subfertility, a lifestyle intervention may reduce BMI. Future studies should compare a combination of pharmacological and lifestyle interventions for obese women with subfertility.
Clinicians primarily recommend weight loss for obese women seeking pregnancy. The effectiveness of interventions aimed at weight loss in obese women with subfertility is unclear.
To assess the effectiveness and safety of pharmacological and non-pharmacological strategies compared with each other, placebo, or no treatment for achieving weight loss in obese women with subfertility.
We searched the CGF Specialised Register, CENTRAL, MEDLINE, Embase, PsycINFO, and AMED from inception to 18 August 2020. We also checked reference lists and contacted experts in the field for additional relevant papers.
We included published and unpublished randomised controlled trials in which weight loss was the main goal of the intervention. Our primary effectiveness outcomes were live birth or ongoing pregnancy and primary safety outcomes were miscarriage and adverse events. Secondary outcomes included clinical pregnancy, weight change, quality of life, and mental health outcome.
Review authors followed standard Cochrane methodology.
This review includes 10 trials. Evidence was of very low to low quality: the main limitations were due to lack of studies and poor reporting of study methods. The main reasons for downgrading evidence were lack of details by which to judge risk of bias (randomisation and allocation concealment), lack of blinding, and imprecision.
Non-pharmacological intervention versus no intervention or placebo
Evidence is insufficient to determine whether a diet or lifestyle intervention compared to no intervention affects live birth (odds ratio (OR) 0.85, 95% confidence interval (CI) 0.65 to 1.11; 918 women, 3 studies; I² = 78%; low-quality evidence). This suggests that if the chance of live birth following no intervention is assumed to be 43%, the chance following diet or lifestyle changes would be 33% to 46%. We are uncertain if lifestyle change compared with no intervention affects miscarriage rate (OR 1.54, 95% CI 0.99 to 2.39; 917 women, 3 studies; I² = 0%; very low-quality evidence). Evidence is insufficient to determine whether lifestyle change compared with no intervention affects clinical pregnancy (OR 1.06, 95% CI 0.81 to 1.40; 917 women, 3 studies; I² = 73%; low-quality evidence). Lifestyle intervention resulted in a decrease in body mass index (BMI), but data were not pooled due to heterogeneity in effect (mean difference (MD) -3.70, 95% CI -4.10 to -3.30; 305 women, 1 study; low-quality evidence; and MD -1.80, 95% CI -2.67 to -0.93; 43 women, 1 study; very low-quality evidence).
Non-pharmacological versus non-pharmacological intervention
We are uncertain whether intensive weight loss interventions compared to standard care nutrition counselling affects live birth (OR 11.00, 95% CI 0.43 to 284; 11 women, 1 study; very low-quality evidence), clinical pregnancy (OR 11.00, 95% CI 0.43 to 284; 11 women, 1 study; very low-quality evidence), BMI (MD -3.00, 95% CI -5.37 to -0.63; 11 women, 1 study; very low-quality evidence), weight change (MD -9.00, 95% CI -15.50 to -2.50; 11 women, 1 study; very low-quality evidence), quality of life (MD 0.06, 95% CI -0.03 to 0.15; 11 women, 1 study; very low-quality evidence), or mental health (MD -7.00, 95% CI -13.92 to -0.08; 11 women, 1 study; very low-quality evidence). No study reported on adverse events .
Pharmacological versus pharmacological intervention
For metformin plus liraglutide compared to metformin we are uncertain of an effect on the adverse events nausea (OR 7.22, 95% CI 0.72 to 72.7; 28 women, 1 study; very low-quality evidence), diarrhoea (OR 0.31, 95% CI 0.01 to 8.3; 28 women, 1 study; very low-quality evidence), and headache (OR 5.80, 95% CI 0.25 to 133; 28 women, 1 study; very low-quality evidence). We are uncertain if a combination of metformin plus liraglutide vs metformin affects BMI (MD 2.1, 95% CI -0.42 to 2.62; 28 women, 1 study; very low-quality evidence) and total body fat (MD -0.50, 95% CI -4.65 to 3.65; 28 women, 1 study; very low-quality evidence).
For metformin, clomiphene, and L-carnitine versus metformin, clomiphene, and placebo, we are uncertain of an effect on miscarriage (OR 3.58, 95% CI 0.73 to 17.55; 274 women, 1 study; very low-quality evidence), clinical pregnancy (OR 5.56, 95% CI 2.57 to 12.02; 274 women, 1 study; very low-quality evidence) or BMI (MD -0.3, 95% CI 1.17 to 0.57, 274 women, 1 study, very low-quality evidence).
We are uncertain if dexfenfluramine versus placebo affects weight loss in kilograms (MD -0.10, 95% CI -2.77 to 2.57; 21 women, 1 study; very low-quality evidence). No study reported on live birth, quality of life, or mental health outcomes.
Pharmacological intervention versus no intervention or placebo
We are uncertain if metformin compared with placebo affects live birth (OR 1.57, 95% CI 0.44 to 5.57; 65 women, 1 study; very low-quality evidence). This suggests that if the chance of live birth following placebo is assumed to be 15%, the chance following metformin would be 7% to 50%. We are uncertain if metformin compared with placebo affects gastrointestinal adverse events (OR 0.91, 95% CI 0.32 to 2.57; 65 women, 1 study; very low-quality evidence) or miscarriage (OR 0.50, 95% CI 0.04 to 5.80; 65 women, 1 study; very low-quality evidence) or clinical pregnancy (OR 2.67, 95% CI 0.90 to 7.93; 96 women, 2 studies; I² = 48%; very low-quality evidence). We are also uncertain if diet combined with metformin versus diet and placebo affects BMI (MD -0.30, 95% CI -2.16 to 1.56; 143 women, 1 study; very low-quality evidence) or waist-to-hip ratio (WHR) (MD 2.00, 95% CI -2.21 to 6.21; 143 women, 1 study; very low-quality evidence).
Pharmacological versus non-pharmacological intervention
No study undertook this comparison.