{"doi":"10.1111/ppe.12946","title":"Interpregnancy interval and preterm delivery: An empirical comparison of between‐persons and within‐sibship designs","abstract":"BACKGROUND: Short interpregnancy interval has been associated with increased risk of preterm delivery; recent studies employing within-sibship designs suggest that this risk may be exaggerated. There are unresolved issues regarding properties of this design. OBJECTIVES: To compare directly the results, for short intervals, of between-person and within-sibship analyses when applied to the same target population. METHODS: Cross-sectional data are from the National Survey of Family Growth, a statistically representative survey of women and men in the USA, 2006-2015. Participants provided a complete pregnancy history including outcome, duration and ending date, enabling calculation of interval. Conventional analysis employed log-linear regression, controlling survey design, early life events, demographic variables, pregnancy intendedness, breastfeeding of the previous birth and obstetric history. Within-sibship analyses, utilising conditional log-linear regression, controlled the same variables, except those remaining static within each participant. RESULTS: Among participants with at least three live- or stillbirths, the percentage of pregnancies in each interval, and the percent of deliveries that were preterm following that interval were 9.2%, 14.6% for <6, and 14.7%, 15.4% for 6-11, versus 12.2%, 14.7% for 18-23 months. Among participants with at least three live- or stillborn infants, those in the within-sibship analysis had a higher risk profile than comparably parous, ineligible participants. In a between-participant analysis, among those included in within-sibship models, the adjusted risk ratios (vs 18-23 months) for preterm delivery for intervals <6 and 6-11 months were 0.74 (95% CI 0.63, 0.88) and 0.85 (95% CI 0.74, 0.98). The corresponding risk ratios were 0.56 (95% CI 0.14, 2.30) and 0.49 (95% CI 0.13, 1.80) for those ineligible for the within-sibship models. CONCLUSIONS: When comparable analyses were employed, the association between interval and preterm delivery was similar between participants included in the within-sibship analysis and those ineligible for the within-sibship analysis, but differed from those in the full cohort, perhaps due to different target populations.","journal":"Paediatric and Perinatal Epidemiology","year":2022,"id":291674,"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":0.9563,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2022-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":451916,"name":"Erinn M. Hade","orcid":"0000-0001-8977-6443","position":1,"is_corresponding":false},{"id":375622,"name":"Mark A. Klebanoff","orcid":null,"position":0,"is_corresponding":true}],"reference_count":27,"raw_metadata":null,"created_at":"2026-07-19T00:30:38.420009Z","pmid":"36511351","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":[]}