{"doi":"10.1111/1471-0528.18301","title":"What Is the Safest Population‐Level Caesarean Delivery Rate? A National Cohort Study Using Natural Variation","abstract":"OBJECTIVE: Ten to fifteen per cent has been proposed for many decades as the optimal level of caesarean section, with little supporting data. Norway provides a natural experiment in which local variations in the use of caesarean section can be related to health outcomes in the context of free access to high-quality medical services. DESIGN: Prospective national cohort. SETTING: Norway. POPULATION: Norwegian deliveries 1995-2014. METHODS: We calculated annual rates of caesarean delivery and health outcomes for 435 municipalities. To avoid hospital referral bias, the mother's municipality of residence was the unit of analysis. Caesarean-delivery rates in each year were based on the 2 years before and after, avoiding indication bias. Analyses were adjusted for year, with additional adjustments in sensitivity analyses. MAIN OUTCOME MEASURES: Maternal mortality, severe maternal haemorrhage and perineal tears; stillbirth and neonatal death, neonatal encephalopathy and cerebral palsy. RESULTS: There were 1 172 546 deliveries across 8647 municipality-year combinations over a 20-year period. Caesarean rates across municipalities ranged from about 10% to 20%, with quartile values of 13%, 16% (median) and 18%. Most adverse outcomes were least frequent in municipalities with caesarean rates above 15%. Lower rates of caesarean delivery were associated with more frequent occurrence of perineal tears (OR 1.41, 95% confidence interval 1.36-1.46), neonatal encephalopathy (OR 1.91, 1.71-2.13), cerebral palsy (1.48, 1.24-1.77) and stillbirths (OR 1.07, 0.99-1.17), but also with less frequent maternal haemorrhage (OR 0.81, 0.77-0.85). Further adjustments had minimal effect on estimates. CONCLUSION: In Norway, a country with free access to high-quality medical care, a local caesarean-delivery rate of 10% was associated with nearly a two-fold risk of neonatal encephalopathy and a 50% higher occurrence of cerebral palsy compared with areas with a caesarean-delivery rate of 20%.","journal":"BJOG An International Journal of Obstetrics & Gynaecology","year":2025,"id":526243,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":3,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.6024,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":433685,"name":"Allen J. Wilcox","orcid":"0000-0002-3376-1311","position":1,"is_corresponding":false},{"id":433683,"name":"Rolv T. Lie","orcid":"0000-0001-6287-4051","position":2,"is_corresponding":false},{"id":434821,"name":"Dag Moster","orcid":null,"position":0,"is_corresponding":true}],"reference_count":30,"raw_metadata":null,"created_at":"2026-07-19T02:50:30.402772Z","pmid":"40654044","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}