title: A population-based case-control study of fetal growth, gestational age, and maternal breast cancer.
abstract: Fetal growth or gestational age in a woman's pregnancies may modify pregnancy-related breast cancer risk, yet studies of these exposures are few. The authors conducted a population-based case-control study among parous Michigan women aged ≤50 years using linked Michigan Cancer Registry (1985-2004) and Michigan livebirth records (1978-2004). Breast cancer cases (n = 7,591) were matched 1:4 to controls (n = 28,382) on maternal birth year and race. Using conditional logistic regression, the authors examined the associations of gestational age (in weeks) and fetal growth (defined using birth weight percentiles for gestational age) in first and last births with breast cancer risk. Having a small-for-gestational-age or large-for-gestational-age infant at a maternal first or last birth was not associated with breast cancer risk, but having a small-for-gestational-age infant at a last birth at ≥30 years modestly reduced risk: odds ratio = 0.82 (95% confidence interval: 0.68, 0.98). First delivery at <32 or >41 weeks also modestly reduced risk: odds ratio = 0.80 (95% confidence interval: 0.62, 1.04) or 0.92 (95% confidence interval: 0.85, 0.99), respectively. In the largest case-control study to date, fetal growth was not associated with overall breast cancer risk in women aged ≤50, and there was some evidence for reduced breast cancer risk for early or late gestational age in first births only.
authors.affiliation: Division of Epidemiology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37203-1738, USA. sarah.nechuta@vanderbilt.edu
authors.forename: Sarah
authors.initials: S
authors.lastname: Nechuta
authors.forename: Nigel
authors.initials: N
authors.lastname: Paneth
authors.forename: Dorothy R
authors.initials: DR
authors.lastname: Pathak
authors.forename: Joseph
authors.initials: J
authors.lastname: Gardiner
authors.forename: Glenn
authors.initials: G
authors.lastname: Copeland
authors.forename: Ellen M
authors.initials: EM
authors.lastname: Velie
mesh_terms: D000328:Adult; D001724:Birth Weight; D001943:Breast Neoplasms / Q000453:epidemiology*; D018270:Carcinoma, Ductal, Breast / Q000453:epidemiology; D018275:Carcinoma, Lobular / Q000453:epidemiology; D016022:Case-Control Studies; D005260:Female; D047109:Fetal Development; D005865:Gestational Age; D006801:Humans; D008875:Middle Aged; D011247:Pregnancy; D012307:Risk Factors; D012959:Socioeconomic Factors