Links between breast cancer and birth weight: an empirical test of the hypothesized association between size at birth and premenopausal adult progesterone concentrations
Some studies have reported that birth size is a risk factor for breast cancer, but the reasons for this observation are unknown. Ovarian hormone concentrations may be a link between birth size and breast cancer, but the few tests of this hypothesis are inconsistent, perhaps because of differences in sample composition, inclusion of anovulatory cycles, or use of one hormonal measurement per woman. We present results from the first study to use daily hormonal measurements throughout a woman’s complete ovulatory cycle to test the hypothesized relationship between birth size and adult progesterone concentrations. We used a study sample and accompanying data set previously obtained for another research project in which we had collected daily urine samples from 63 healthy premenopausal women throughout a menstrual cycle. Multivariate regression was used to test for trends of individual progesterone indices (from 55 ovulatory cycles) with birth weight or ponderal index, while controlling for age, adult BMI, and age at menarche. Our main finding was that neither birth weight nor ponderal index was associated with biologically significant variation in luteal progesterone indices; the best-estimated effect sizes of birth size on these progesterone indices were small (3.7–10.2 %). BMI was the only significant predictor of mean peak urinary progesterone, but it explained <6 % of the variance. Our findings, in light of what is currently known regarding associations of breast cancer risk with birth size and adult size, suggest that environmental factors (particularly those that vary by socioeconomic status and affect growth) may underlie associations between birth size and cancer risks without there being any association of birth size with adult ovarian hormone concentrations.
We would like to thank the participants for being involved with this study, the assistants who helped with data collection and entry, and the Max Planck Institute for Evolutionary Anthropology (MPI-EVA) for facilities and logistical support. Financial support was provided by a Fulbright Senior Research Fellowship (VJV), MPI-EVA, and Indiana University. Thank you also to Tierney Lorenz, Sophia Graham, and Rebecca Bedwell for assistance with statistical analyses and manuscript preparation and to the editor and two anonymous reviewers for comments on earlier versions of this manuscript. The authors declare that they have no conflict of interest.
- 7.Sanderson M, Williams MA, Malone KE, et al (1996) Perinatal factors and risk of breast cancer. Epidemiology 34–37Google Scholar
- 15.Martin JA, Hamilton BE, Ventura SJ et al (2013) Births: final data for 2011. Natl Vital Stat Rep 62:1–90Google Scholar
- 16.Indrayan A (2012) Medical biostatistics, 3rd edition. CRC PressGoogle Scholar
- 23.Yang TO, Reeves GK, Green J, et al (2014) Birth weight and adult cancer incidence: large prospective study and meta-analysis. Ann Oncol mdu214Google Scholar
- 29.Rohrer F (1921) Der Index der Körperfülle als Maß des Ernährungszustandes. Munch Med Wochenschr 68:580–582Google Scholar
- 32.Walther FJ, Ramaekers LHJ (1982) The ponderal index as a measure of the nutritional status at birth and its relation to some aspects of neonatal morbidityGoogle Scholar
- 42.Potischman N, Christine A, Swanson PS, Hoover RN (1996) Reversal of relation between body mass and endogenous estrogen concentrations with menopausal status. Breast Cancer 13:15Google Scholar