{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"medRxiv"}],"indexed":{"date-parts":[[2026,4,28]],"date-time":"2026-04-28T07:02:58Z","timestamp":1777359778643,"version":"3.51.4"},"posted":{"date-parts":[[2026,4,24]]},"group-title":"Obstetrics and Gynecology","reference-count":49,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,4,24]],"date-time":"2026-04-24T00:00:00Z","timestamp":1776988800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,4,24]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                <jats:p>\n                  Preconception weight loss by metabolic-bariatric surgery (MBS) improves maternal-fetal outcomes, but little is known about its impact on offspring growth and health. The preconception bariatric surgery and child health outcomes (POSIT) study aims to estimate the effects of maternal MBS-induced preconception weight loss on infant and childhood body size, growth, and related outcomes. This report presents the methods used to construct the POSIT cohort and its baseline characteristics. This retrospective cohort study sampled members from a United States healthcare system aged 18 and older with a singleton, live birth to create three study groups: 1) a treatment group including women who underwent preconception MBS and subsequently became pregnant (n=1,374); 2) a control group matched to the MBS pre-surgery body mass index (BMI) (pre-surgery controls, n=13,740); and 3) a second control group matched to the MBS post-surgical, pre-pregnancy BMI (pre-pregnancy controls, n=13,740). MBS and pre-surgery BMI controls showed slight imbalances in that pre-surgery BMI controls were on average \u223c6 months younger, had 0.6 lower BMI (44.5 kg\/m\n                  <jats:sup>2<\/jats:sup>\n                  ) at the time of their pregnancy and were more likely to have become pregnant in earlier years than the MBS group prior to surgery. MBS and pre-pregnancy controls had comparable age (mean \u00b1 SD 33 \u00b1 5 years), pre-pregnancy BMI (33 \u00b1 6 kg\/m\n                  <jats:sup>2<\/jats:sup>\n                  ), and year of delivery. Following matching, the MBS group had similar socioeconomic and health disparities as the pre-surgery control group, and both were worse than pre-pregnancy control group. Pregestational maternal comorbidity index improved after MBS and matched the pre-pregnancy controls. Upon extraction of offspring growth patterns and mediation analyses of maternal weight loss and metabolic responses to MBS, study findings will investigate effects of preconception weight loss by MBS on short- and long-term child health outcomes. Results will guide future studies focusing on improving maternal preconception weight and maternal-fetal outcomes.\n                <\/jats:p>","DOI":"10.64898\/2026.04.22.26351521","type":"posted-content","created":{"date-parts":[[2026,4,24]],"date-time":"2026-04-24T22:50:18Z","timestamp":1777071018000},"source":"Crossref","is-referenced-by-count":0,"title":["Preconception metabolic-bariatric surgery and child health outcomes: Identification and cohort profile of the POSIT study protocol"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5505-6333","authenticated-orcid":false,"given":"Jonathan Q.","family":"Purnell","sequence":"first","affiliation":[{"name":"Oregon Health & Science University, Portland, Oregon, United States of America"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Darios","family":"Getahun","sequence":"additional","affiliation":[{"name":"Department of Research & Evaluation, Kaiser Permanente Southern California, Pasadena, California, United States of America"},{"name":"Department of Health Systems Science, Kaiser Permanente Bernard J. Tyson School of Medicine, Pasadena, California, United States of America"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kimberly K.","family":"Vesco","sequence":"additional","affiliation":[{"name":"Kaiser Permanente Center for Health Research, Portland, Oregon, United States of America"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4828-3180","authenticated-orcid":false,"given":"Sijia","family":"Qiu","sequence":"additional","affiliation":[{"name":"Department of Research & Evaluation, Kaiser Permanente Southern California, Pasadena, California, United States of America"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8397-3729","authenticated-orcid":false,"given":"Jiaxiao M.","family":"Shi","sequence":"additional","affiliation":[{"name":"Department of Research & Evaluation, Kaiser Permanente Southern California, Pasadena, California, United States of America"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Carmen P.","family":"Wong","sequence":"additional","affiliation":[{"name":"Kaiser Permanente Center for Integrated Health Care Research, Honolulu, Hawaii, United States of America"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Padma","family":"Koppolu","sequence":"additional","affiliation":[{"name":"Kaiser Permanente Center for Health Research, Portland, Oregon, United States of America"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Theresa M.","family":"Im","sequence":"additional","affiliation":[{"name":"Department of Research & Evaluation, Kaiser Permanente Southern California, Pasadena, California, United States of America"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Caryn E.","family":"Oshiro","sequence":"additional","affiliation":[{"name":"Kaiser Permanente Center for Integrated Health Care Research, Honolulu, Hawaii, United States of America"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Janne","family":"Boone-Heinonen","sequence":"additional","affiliation":[{"name":"Department of Epidemiology and Biostatistics, University of California at San Francisco, San Francisco, California, United States of America"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"54368","reference":[{"key":"2026042723250825000_2026.04.22.26351521v1.1","doi-asserted-by":"publisher","DOI":"10.15620\/cdc\/159281"},{"issue":"360","key":"2026042723250825000_2026.04.22.26351521v1.2","first-page":"1","article-title":"Prevalence of Obesity and Severe Obesity Among Adults: United States, 2017-2018","year":"2020","journal-title":"NCHS Data Brief"},{"key":"2026042723250825000_2026.04.22.26351521v1.3","doi-asserted-by":"publisher","DOI":"10.15585\/mmwr.mm665152a3"},{"key":"2026042723250825000_2026.04.22.26351521v1.4","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMra0708473"},{"key":"2026042723250825000_2026.04.22.26351521v1.5","doi-asserted-by":"publisher","DOI":"10.3945\/ajcn.2008.27416"},{"key":"2026042723250825000_2026.04.22.26351521v1.6","doi-asserted-by":"publisher","DOI":"10.1136\/bmj.f4539"},{"key":"2026042723250825000_2026.04.22.26351521v1.7","doi-asserted-by":"publisher","DOI":"10.1111\/pedi.12273"},{"key":"2026042723250825000_2026.04.22.26351521v1.8","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pmed.1002817"},{"key":"2026042723250825000_2026.04.22.26351521v1.9","doi-asserted-by":"publisher","DOI":"10.1016\/S2213-8587(20)30151-0"},{"key":"2026042723250825000_2026.04.22.26351521v1.10","doi-asserted-by":"publisher","DOI":"10.1001\/jama.2021.0247"},{"key":"2026042723250825000_2026.04.22.26351521v1.11","doi-asserted-by":"publisher","DOI":"10.1136\/bmj.e2088"},{"key":"2026042723250825000_2026.04.22.26351521v1.12","doi-asserted-by":"publisher","DOI":"10.1002\/14651858.CD007145.pub3"},{"key":"2026042723250825000_2026.04.22.26351521v1.13","doi-asserted-by":"publisher","DOI":"10.1002\/oby.21330"},{"key":"2026042723250825000_2026.04.22.26351521v1.14","doi-asserted-by":"publisher","DOI":"10.1002\/oby.22250"},{"key":"2026042723250825000_2026.04.22.26351521v1.15","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa012512"},{"key":"2026042723250825000_2026.04.22.26351521v1.16","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa1212914"},{"key":"2026042723250825000_2026.04.22.26351521v1.17","unstructured":"Tchang BG , Aras M , Kumar RB , Aronne LJ . 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