肥満女性のIVF希望者、減量後の自然妊娠確率が47%増加(Women with obesity seeking IVF found to be 47% more likely to conceive naturally after weight loss)

2025-08-13

2025-08-12 オックスフォード大学

オックスフォード大学の研究によると、肥満で体外受精(IVF)を希望する女性がIVF前に体重減少プログラムに参加すると、自然妊娠の可能性が47%、自然妊娠またはIVFによる妊娠率が21%向上することが分かった。12件の試験(計1,921人)を分析した結果、介入群は比較群より平均約4kg多く減量。介入には食事・運動・脂肪吸収抑制薬・旧世代GLP-1作動薬などが含まれた。この知見は、BMI30以上の女性にIVF助成を制限する英国の現行制度の見直しや、公平な治療アクセス改善に寄与する可能性がある。今後は、どの方法が最も効果的で誰に適しているかを特定するため、大規模で質の高い研究が必要とされる。

<関連情報>

肥満女性における体外受精前の体重減少が生殖結果に与える影響:系統的レビューとメタ分析 The Effect of Weight Loss Before In Vitro Fertilization on Reproductive Outcomes in Women With Obesity: A Systematic Review and Meta-analysis

Moscho Michalopoulou, DPhil (Oxon), Susan Ann Jebb, PhD, Alice Hobson, MSc, Shen Chuen Khaw, MBChB, Richard Stevens, PhD, Pedro Melo, PhD, Stella Jane Pierce Haffner, MSc, …, and Nerys Marie Astbury, PhD
Annals of Internal Medicine Published:12 August 2025
DOI:https://doi.org/10.7326/ANNALS-24-01025

Abstract

Background:

It is unclear whether weight loss before in vitro fertilization (IVF) improves reproductive outcomes in women with obesity.

Purpose:

To assess whether weight loss interventions before IVF improve reproductive outcomes.

Data Sources:

Five electronic databases through 27 May 2025.

Study Selection:

Randomized controlled trials (RCTs) in women with obesity who were offered a weight loss intervention before planned IVF.

Data Extraction:

Dual independent screening, data extraction, and assessment of risk of bias (RoB) and certainty of evidence. Primary outcomes were pregnancy and live birth rates. Where appropriate, studies were pooled using random-effects meta-analyses.

Data Synthesis:

Twelve RCTs (1921 randomly assigned participants) were included, 7 of which had high RoB. There was moderate certainty that pre-IVF weight loss interventions were associated with an increase in total pregnancy rates (risk ratio [RR], 1.21 [95% CI, 1.02 to 1.44]; 11 studies) and pregnancies resulting from unassisted conception (RR, 1.47 [CI, 1.26 to 1.73]; 10 studies), whereas the effect on pregnancies resulting solely from IVF was uncertain. Weight loss interventions were not associated with pregnancy loss rates (RR, 1.05 [CI, 0.98 to 1.13]; 8 studies; moderate certainty), but their effect on live birth rates was unclear (RR, 1.15 [CI, 0.95 to 1.40]; 9 studies; very low certainty).

Limitations:

Studies were small, had high RoB, and often did not report important outcomes, such as live births. Substantial clinical and methodological heterogeneity was unexplained by exploratory analyses.

Conclusion:

Weight loss interventions before IVF appear to increase the chances of pregnancy, especially unassisted conceptions. However, studies were small, and heterogeneity made it difficult to determine the benefit of any particular intervention.