A population-based case-control study of fetal growth, gestational age, and maternal breast cancer.
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.
Nechuta
Sarah
S
Division of Epidemiology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37203-1738, USA. sarah.nechuta@vanderbilt.edu
Paneth
Nigel
N
Pathak
Dorothy R
DR
Gardiner
Joseph
J
Copeland
Glenn
G
Velie
Ellen M
EM
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