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Odds ratio (OR) (dichotomous data), standardised mean difference (SMD) (continuous data) and 95% CIs were calculated.<\/jats:p><\/jats:sec><jats:sec><jats:title>Main results<\/jats:title><jats:p>Nine eligible studies were identified: one natural conception and eight assisted reproductive technology (ART). Aggregated data revealed women with BMI \u226525 were less likely to attain clinical pregnancy (OR 0.76, 95% CIs 0.62 to 0.93, p=0.007), with BMI \u226530 associated with a further decreased likelihood of clinical pregnancy (OR 0.61, 95% CIs 0.39 to 0.98, p=0.04). Women with raised BMI required longer duration of stimulation (SMD=0.08, 95% CIs 0.00 to 0.16, p=0.04) and obtained reduced oocytes (SMD=\u22120.11, 95% CIs \u22120.18 to \u22120.04, p=0.002).<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>These data demonstrate an adverse impact of being overweight\/obese on ART outcomes in women with no other diagnosed medical comorbidities and highlight the distinct lack of data concerning the effects of isolated obesity on natural conception. Infertility represents an enormous burden for couples and society; it is essential to identify and tackle modifiable risk factors to improve chances of conception.<\/jats:p><\/jats:sec><jats:sec><jats:title>PROSPERO registration number<\/jats:title><jats:p>CRD42022293631.<\/jats:p><\/jats:sec>","DOI":"10.1136\/bmjopen-2023-082123","type":"journal-article","created":{"date-parts":[[2024,11,1]],"date-time":"2024-11-01T10:00:11Z","timestamp":1730455211000},"page":"e082123","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":19,"title":["Impact of BMI on fertility in an otherwise healthy population: a systematic review and meta-analysis"],"prefix":"10.1136","volume":"14","author":[{"given":"Florence","family":"Turner","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Simon G","family":"Powell","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hannan","family":"Al-Lamee","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anjali","family":"Gadhvi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ellen","family":"Palmer","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andrew","family":"Drakeley","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2666-4986","authenticated-orcid":false,"given":"Victoria S","family":"Sprung","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dharani","family":"Hapangama","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3633-1592","authenticated-orcid":false,"given":"Nicola","family":"Tempest","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2024,11,1]]},"reference":[{"key":"2024110103000612000_14.10.e082123.1","unstructured":"WHO . 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