{"doi":"10.1111/1471-0528.14672","title":"Physical activity and the risk of preterm birth: a systematic review and meta‐analysis of epidemiological studies","abstract":"<jats:sec><jats:title>Background</jats:title><jats:p>Physical activity has been inconsistently associated with risk of preterm birth, and the strength of the association and the shape of the dose–response relationship needs clarification.</jats:p></jats:sec><jats:sec><jats:title>Objectives</jats:title><jats:p>To conduct a systematic review and dose–response meta‐analysis to clarify the association between physical activity and risk of preterm birth.</jats:p></jats:sec><jats:sec><jats:title>Search strategy</jats:title><jats:p>PubMed, Embase and Ovid databases were searched for relevant studies up to 9 February 2017.</jats:p></jats:sec><jats:sec><jats:title>Selection criteria</jats:title><jats:p>Studies with a prospective cohort, case‐cohort, nested case‐control or randomized study design were included.</jats:p></jats:sec><jats:sec><jats:title>Data collection and analysis</jats:title><jats:p>Data were extracted by one reviewer and checked for accuracy by a second reviewer. Summary relative risks (<jats:styled-content style=\"fixed-case\">RR</jats:styled-content>s) were estimated using a random effects model.</jats:p></jats:sec><jats:sec><jats:title>Main results</jats:title><jats:p>Forty‐one studies (43 publications) including 20 randomized trials and 21 cohort studies were included. The summary <jats:styled-content style=\"fixed-case\">RR</jats:styled-content> for high versus low activity was 0.87 [95% confidence interval (<jats:styled-content style=\"fixed-case\">CI</jats:styled-content>): 0.70–1.06, <jats:italic>I</jats:italic><jats:sup>2</jats:sup> = 17%, <jats:italic>n</jats:italic> = 5] for physical activity before pregnancy, and it was 0.86 (95% <jats:styled-content style=\"fixed-case\">CI</jats:styled-content>: 0.78–0.95, <jats:italic>I</jats:italic><jats:sup>2</jats:sup> = 0%, <jats:italic>n</jats:italic> = 30) for early pregnancy physical activity. The summary <jats:styled-content style=\"fixed-case\">RR</jats:styled-content> for a 3 hours per week increment in leisure‐time activity was 0.90 (95% <jats:styled-content style=\"fixed-case\">CI</jats:styled-content>: 0.85–0.95, <jats:italic>I</jats:italic><jats:sup>2</jats:sup> = 0%, <jats:italic>n</jats:italic> = 5). There was evidence of a nonlinear association between physical activity and preterm birth, <jats:italic>P</jats:italic><jats:sub>nonlinearity</jats:sub> &lt; 0.0001, with the lowest risk observed at 2–4 hours per week of activity.</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>This meta‐analysis suggests that higher leisure‐time activity is associated with reduced risk of preterm birth. Further randomized controlled trials with sufficient frequency and duration of activity to reduce the risk and with larger sample sizes are needed to conclusively demonstrate an association.</jats:p></jats:sec><jats:sec><jats:title>Tweetable abstract</jats:title><jats:p>Physically active compared with inactive women have an 10–14% reduction in the risk of preterm birth.</jats:p></jats:sec>","journal":"BJOG: An International Journal of Obstetrics &amp; Gynaecology","year":2017,"id":16356,"datarank":3.286722429271217,"base_score":4.553876891600541,"endowment":4.553876891600541,"self_citation_contribution":0.6830815337400812,"citation_network_contribution":2.603640895531136,"self_endowment_contribution":0.6830815337400812,"citer_contribution":2.603640895531136,"corpus_percentile":null,"corpus_rank":null,"citation_count":94,"citer_count":88,"citers_with_citation_signal":70,"citers_with_endowment":70,"datacite_reuse_total":6,"is_dataset":false,"is_dataset_confidence":null,"is_data_producer":false,"deposit_databanks":null,"is_oa":false,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":null,"fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":121034,"name":"S Schlesinger","orcid":null,"position":1,"is_corresponding":false},{"id":121035,"name":"T Henriksen","orcid":null,"position":2,"is_corresponding":false},{"id":121036,"name":"OD Saugstad","orcid":null,"position":3,"is_corresponding":false},{"id":121037,"name":"S Tonstad","orcid":null,"position":4,"is_corresponding":false},{"id":121033,"name":"D Aune","orcid":null,"position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"base_score":4.553876891600541,"endowment":4.553876891600541,"datacite_reuse_total":6,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"28374930","pmcid":null,"openalex_id":"https://openalex.org/W2605271650","authors":[],"funders":[{"funder_name":"Helse Midt-Norge","grant_id":"","title":null},{"funder_name":"Norges Teknisk-Naturvitenskapelige Universitet","grant_id":"","title":null},{"funder_name":"Centro de Investigación Biomédica en Red de Salud Mental","grant_id":"","title":null},{"funder_name":"National Institute for Health Research (NIHR)","grant_id":"","title":null}],"total_grants":4,"fwci":4.8649,"citation_percentile":0.95892474,"influential_citations":2,"citation_trend":[{"year":2018,"count":6},{"year":2019,"count":6},{"year":2020,"count":16},{"year":2021,"count":12},{"year":2022,"count":15},{"year":2023,"count":9},{"year":2024,"count":9},{"year":2025,"count":13},{"year":2026,"count":8}],"oa_status":"closed","license":"http://onlinelibrary.wiley.com/termsAndConditions#vor","oa_locations":[{"url":"https://obgyn.onlinelibrary.wiley.com/doi/pdfdirect/10.1111/1471-0528.14672","host_type":"BRONZE"},{"url":"https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2F1471-0528.14672","host_type":"publisher"},{"url":"https://obgyn.onlinelibrary.wiley.com/doi/pdf/10.1111/1471-0528.14672","host_type":"publisher"},{"url":"https://doi.org/10.1111/1471-0528.14672","host_type":"journal"},{"url":"https://pubmed.ncbi.nlm.nih.gov/28374930","host_type":"repository"},{"url":"http://hdl.handle.net/10044/1/60985","host_type":"repository"}],"fields_of_study":["Preterm Birth and Chorioamnionitis","Gestational Diabetes Research and Management","Infant Development and Preterm Care","Medicine","Exercise","Female","Humans","Pregnancy","Premature Birth","Prenatal Care","Prenatal Nutritional Physiological Phenomena","Risk Factors"],"mesh_terms":["Female","Humans","Pregnancy","Prenatal Care","Risk Factors","Exercise","Prenatal Nutritional Physiological Phenomena","Premature Birth"],"keywords":["Medicine","Relative risk","Meta-analysis","Randomized controlled trial","Cohort study","Confidence interval","Pregnancy","Prospective cohort study","Epidemiology","Cohort","Systematic review","Premature birth","Lower risk","Obstetrics","Pediatrics","Internal medicine","MEDLINE","Gestational age","Biology","Physical Activity","Preterm Birth"],"sdg_mappings":[{"sdg_number":0,"sdg_label":"Good health and well-being"}],"linked_datasets":[{"doi":"10.6084/m9.figshare.13024052.v1","title":"Additional file 1 of Epidemiology of preterm birth in Ethiopia: systematic review and meta-analysis","publisher":"figshare","resource_type":"JournalArticle"},{"doi":"10.6084/m9.figshare.13024052","title":"Additional file 1 of Epidemiology of preterm birth in Ethiopia: systematic review and meta-analysis","publisher":"figshare","resource_type":"JournalArticle"},{"doi":"10.6084/m9.figshare.19396149.v1","title":"Additional file 1 of Are pre- and early pregnancy lifestyle factors associated with the risk of preterm birth? 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