Multiple births, sex of children and subsequent breast‐cancer risk for the mothers: A prospective study in Norway
- 27 January 1995
- journal article
- research article
- Published by Wiley in International Journal of Cancer
- Vol. 60 (3) , 341-344
- https://doi.org/10.1002/ijc.2910600311
Abstract
Endocrinological changes occurring during pregnancy may influence the subsequent cancer risk of the mother. Further, the endocrinological milieu may differ according to different birth characteristics. In the present study possible relations between multiple births, sex of children and breast‐cancer risk were examined in a population‐based, prospective study of 802,269 parous Norwegian women aged 20–56 years. A total of 4,782 women were diagnosed with breast cancer during follow‐up. Of these, 97 had ever experienced a multiple birth. We found a slightly lower risk of breast cancer among women ever having had a multiple birth than among women with singletons only (IRR = 0.89, 95% CI = 0.73–1.09). The reduction in risk was mainly observed among women with a multiple last birth. Further, the reduction in risk seemed to diminish with increasing parity, and among women with 4 or more full‐term pregnancies, ever having had a multiple birth was associated with an elevated risk (IRR = 1.48, 95% CI = 0.97–2.25). The sex of the first or last child did not affect the subsequent breast‐cancer risk. Further, we found no associations with the sex distribution among all children or in multiple births, despite a tendency toward a reduced risk among women with several daughters only.Keywords
This publication has 20 references indexed in Scilit:
- Breast Cancer Incidence before Age 55 in Relation to Parity and Age at First and Last BirthsEpidemiology, 1994
- Gender of the first offspring, age at diagnosis, and survival with breast cancer (Utah, United States)Cancer Causes & Control, 1994
- Breast cancer risk in mothers of multiple birthsInternational Journal of Cancer, 1993
- The permanent effect of reproductive events on blood prolactin levels and its relation to breast cancer risk: a population study of postmenopausal womenEuropean Journal of Cancer and Clinical Oncology, 1988
- Prolactin Levels after PregnancyNew England Journal of Medicine, 1987
- Long-Term Effect of a First Pregnancy on the Secretion of ProlactinNew England Journal of Medicine, 1987
- Breast cancer prognosis and the sex of the patient's childrenCancer, 1981
- PREGNANCY, BREAST-CANCER RISK, AND MATERNAL-FETAL GENETICSThe Lancet, 1979
- SEX OF FIRST CHILD AS A PROGNOSTIC FACTOR IN BREAST CANCERThe Lancet, 1978
- TWIN ZYGOSITY AND PRE-ECLAMPSIAThe Lancet, 1977