{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,11]],"date-time":"2026-03-11T19:40:31Z","timestamp":1773258031362,"version":"3.50.1"},"reference-count":47,"publisher":"Wiley","issue":"5","license":[{"start":{"date-parts":[[2019,9,3]],"date-time":"2019-09-03T00:00:00Z","timestamp":1567468800000},"content-version":"vor","delay-in-days":2,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Paediatric Perinatal Epid"],"published-print":{"date-parts":[[2019,9]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Background<\/jats:title><jats:p>Birthweight discordance is well studied, with less known about longitudinal inter\u2010twin differences in foetal growth.<\/jats:p><\/jats:sec><jats:sec><jats:title>Objective<\/jats:title><jats:p>To examine inter\u2010twin per cent differences in EFW (EFW<jats:sub>%<\/jats:sub>), head (HC<jats:sub>%<\/jats:sub>) and abdominal circumference (AC<jats:sub>%<\/jats:sub>), and femur length (FL<jats:sub>%<\/jats:sub>) across gestation in dichorionic twin gestations and explore associated characteristics.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Foetal biometrics were assessed by ultrasound and EFW calculated at \u22646 study visits among women with dichorionic twin pregnancies enrolled in the NICHD Fetal Growth Studies cohort (US, 2012\u20102013). Inter\u2010twin per cent difference was defined: ([Size<jats:sub>larger twin<\/jats:sub>\u00a0\u2212\u00a0Size<jats:sub>smaller twin<\/jats:sub>]\/Size<jats:sub>larger twin<\/jats:sub>\u00a0\u00d7\u00a0100). Linear mixed models evaluated per cent differences in foetal biometrics at 15\u00a0weeks and their change per week overall and by maternal\/neonatal characteristics in unadjusted and adjusted models.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>In 140 pregnancies, inter\u2010twin per cent differences increased across gestation for EFW (0.18%\/week, 95% confidence interval [CI] 0.10, 0.27), HC (0.03%\/week, 95% CI 0.00, 0.06), and AC (0.03%\/week, 95%CI \u22120.01, 0.08) but decreased for FL (\u22120.03%\/week, 95% CI \u22120.09, 0.02). After adjustment, change in EFW<jats:sub>%<\/jats:sub> difference across gestation differed by pre\u2010pregnancy body mass index (BMI [kg\/m<jats:sup>2<\/jats:sup>]; underweight [&lt;18.5]; normal weight [18.5\u201024.9]; overweight [25.0\u201029.9]; obese [\u226530.0]; <jats:italic>P<\/jats:italic><jats:sub>interaction<\/jats:sub>\u00a0=\u00a0.022); and conception method (in vitro fertilisation [IVF], intrauterine insemination, ovulation induction medication, donor egg\/embryo, none; <jats:italic>P<\/jats:italic><jats:sub>interaction<\/jats:sub>\u00a0=\u00a0.060). While EFW<jats:bold><jats:sub>%<\/jats:sub><\/jats:bold> difference increased with normal pre\u2010pregnancy BMI (0.24%\/week, 95% CI 0.12, 0.37), little change was noted with pre\u2010pregnancy obesity (0.01%\/week, 95% CI \u22120.15, 0.17). EFW<jats:bold><jats:sub>%<\/jats:sub><\/jats:bold> difference increased in conceptions without fertility treatments (0.23%\/week, 95% CI 0.11, 0.34) but not IVF conceptions (\u22120.00%\/week, 95% CI \u22120.16, 0.16). Similar patterns of differences across gestation were noted for HC<jats:sub>%<\/jats:sub> by conception method (<jats:italic>P<\/jats:italic><jats:sub>interaction<\/jats:sub>\u00a0=\u00a0.026) and AC<jats:sub>%<\/jats:sub> by pre\u2010pregnancy BMI (<jats:italic>P<\/jats:italic><jats:sub>interaction<\/jats:sub>\u00a0=\u00a0.071); changes in HC<jats:sub>%<\/jats:sub> differed by parity (nulliparous, multiparous; <jats:italic>P<\/jats:italic><jats:sub>interaction<\/jats:sub>\u00a0=\u00a0.004).<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>EFW<jats:bold><jats:sub>%<\/jats:sub><\/jats:bold> difference increased across gestation in dichorionic twins, but remained stable with pre\u2010pregnancy obesity or IVF conception, patterns mirrored for HC and AC. Research is needed to understand pathologic versus physiologic differential twin growth trajectories.<\/jats:p><\/jats:sec>","DOI":"10.1111\/ppe.12570","type":"journal-article","created":{"date-parts":[[2019,9,3]],"date-time":"2019-09-03T08:05:27Z","timestamp":1567497927000},"page":"332-342","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Associations between estimated foetal weight discordance and clinical characteristics within dichorionic twins: The NICHD Fetal Growth Studies"],"prefix":"10.1111","volume":"33","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4660-7716","authenticated-orcid":false,"given":"Melissa M.","family":"Amyx","sequence":"first","affiliation":[{"name":"Division of Intramural Population Health Research, <i>Eunice Kennedy Shriver<\/i> National Institute of Child Health and Human Development National Institutes of Health Bethesda 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