{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"medRxiv"}],"indexed":{"date-parts":[[2026,10,12]],"date-time":"2026-10-12T14:34:41Z","timestamp":1791815681452,"version":"4.3.4"},"posted":{"date-parts":[[2026,6,22]]},"group-title":"Obstetrics and Gynecology","reference-count":36,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,6,22]],"date-time":"2026-06-22T00:00:00Z","timestamp":1782086400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Wellcome Trust and Royal Society","award":["104150\/Z\/14\/Z"],"award-info":[{"award-number":["104150\/Z\/14\/Z"]}]},{"name":"National Institute for Health and Care Research Yorkshire and Humber Applied Research Collaboration and the Programme Grants for Applied Research"},{"DOI":"10.13039\/100010269","name":"Wellcome Trust","doi-asserted-by":"crossref","award":["WT101597MA"],"award-info":[{"award-number":["WT101597MA"]}],"id":[{"id":"10.13039\/100010269","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/100010269","name":"Wellcome Trust","doi-asserted-by":"crossref","award":["WT220390"],"award-info":[{"award-number":["WT220390"]}],"id":[{"id":"10.13039\/100010269","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"crossref","award":["82430106"],"award-info":[{"award-number":["82430106"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"crossref","award":["82461160320"],"award-info":[{"award-number":["82461160320"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"crossref","award":["82273642"],"award-info":[{"award-number":["82273642"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"crossref","award":["82574110"],"award-info":[{"award-number":["82574110"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"crossref"}]},{"name":"Eunice Kennedy Shriver National Institute of Child Health & Human Development of the National Institutes of Health","award":["R01HD101669"],"award-info":[{"award-number":["R01HD101669"]}]},{"name":"Royal Society International Exchanges","award":["IEC\/NSFC\/242502"],"award-info":[{"award-number":["IEC\/NSFC\/242502"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,6,22]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                <jats:sec>\n                  <jats:title>Introduction<\/jats:title>\n                  <jats:p>Birthweight reflects fetal growth from conception. The complications arising from the extremes of fetal growth are well known, but addressing these effectively depends on understanding how and when fetal growth is affected by various maternal and fetal factors. We aimed to compare associations of fetal genetic and maternal environmental factors with fetal weight mid-pregnancy and birthweight.<\/jats:p>\n                <\/jats:sec>\n                <jats:sec>\n                  <jats:title>Material and methods<\/jats:title>\n                  <jats:p>We studied 3110 mother-child pairs from three population-based birth cohorts (UK and China). Estimated fetal weight at \u223c20 weeks gestation (EFW20) and birthweight were the outcomes of interest. Exposures were fetal genetic factors (fetal sex and fetal birthweight genetic score [BW GS]) and maternal factors (maternal BW GS, BMI, fasting plasma glucose [FPG], smoking, age, and parity). Associations were studied using multivariable linear regressions within cohorts and meta-analysed.<\/jats:p>\n                <\/jats:sec>\n                <jats:sec>\n                  <jats:title>Results<\/jats:title>\n                  <jats:p>All exposures were associated with both EFW20 and birthweight, apart from maternal FPG and smoking which were associated with birthweight only. Male fetal sex and a higher maternal BW GS were consistently associated with higher EFW20 and birthweight, whereas the fetal BW GS, maternal FPG, BMI and smoking showed more marked associations later in pregnancy. Maternal age and parity showed directionally opposite associations with EFW20 and birthweight.<\/jats:p>\n                <\/jats:sec>\n                <jats:sec>\n                  <jats:title>Conclusions<\/jats:title>\n                  <jats:p>Fetal genetic and maternal environmental factors vary in their effect on fetal growth in mid-pregnancy compared with late pregnancy. These findings contribute to our understanding of growth across pregnancy and may inform the timing of clinical monitoring of fetal growth and interventions targeting modifiable maternal factors.<\/jats:p>\n                <\/jats:sec>\n                <jats:sec>\n                  <jats:title>Key Message<\/jats:title>\n                  <jats:p>Drivers of fetal growth have been under-studied in their magnitudes and timings across gestation. We show that fetal genetic and maternal environmental factors vary in their associations with fetal growth at \u223c20 weeks compared with later pregnancy.<\/jats:p>\n                <\/jats:sec>","DOI":"10.64898\/2026.06.18.26355970","type":"posted-content","created":{"date-parts":[[2026,6,22]],"date-time":"2026-06-22T22:00:12Z","timestamp":1782165612000},"source":"Crossref","is-referenced-by-count":1,"title":["Genetic and maternal environmental contributions to estimated fetal weight at 20 weeks gestation compared with birthweight"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0009-0008-1488-9484","authenticated-orcid":false,"given":"Rosie A.","family":"Purdy","sequence":"first","affiliation":[{"name":"Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jingxue","family":"Feng","sequence":"additional","affiliation":[{"name":"Division of Birth Cohort Study, Guangzhou Women and Children\u2019s Medical Center, Guangzhou Medical University, Guangzhou, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhenyu","family":"Luo","sequence":"additional","affiliation":[{"name":"Division of Birth Cohort Study, Guangzhou Women and Children\u2019s Medical Center, Guangzhou Medical University, Guangzhou, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Robin N.","family":"Beaumont","sequence":"additional","affiliation":[{"name":"Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andrew T.","family":"Hattersley","sequence":"additional","affiliation":[{"name":"Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jianrong","family":"He","sequence":"additional","affiliation":[{"name":"Division of Birth Cohort Study, Guangzhou Women and Children\u2019s Medical Center, Guangzhou Medical University, Guangzhou, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiu","family":"Qiu","sequence":"additional","affiliation":[{"name":"Division of Birth Cohort Study, Guangzhou Women and Children\u2019s Medical Center, Guangzhou Medical University, Guangzhou, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rachel M.","family":"Freathy","sequence":"additional","affiliation":[{"name":"Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alice E.","family":"Hughes","sequence":"additional","affiliation":[{"name":"Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"54368","reference":[{"key":"2026062502100977000_2026.06.18.26355970v1.1","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pmed.1002228"},{"key":"2026062502100977000_2026.06.18.26355970v1.2","doi-asserted-by":"publisher","DOI":"10.1093\/aje\/kwk071"},{"key":"2026062502100977000_2026.06.18.26355970v1.3","doi-asserted-by":"publisher","DOI":"10.1007\/s11892-004-0080-y"},{"issue":"1","key":"2026062502100977000_2026.06.18.26355970v1.4","doi-asserted-by":"crossref","first-page":"423","DOI":"10.1186\/s12884-025-07518-y","article-title":"The value of fetal growth trajectory during pregnancy in predicting small for gestational age neonates at term","volume":"25","year":"2025","journal-title":"BMC Pregnancy Childbirth"},{"key":"2026062502100977000_2026.06.18.26355970v1.5","doi-asserted-by":"crossref","unstructured":"Hughes AE , De Franco E , Freathy RM , Flanagan SE , Hattersley AT . 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