Table 1. Characteristic of the included studies in this meta-analysis.
| First author, Publication year | Countrya | Study period | Age | Sex | Cases/Cohort | Case diagnosis | measurement method | Matching or adjustment |
| Cohort studies | ||||||||
| Benson, 2008 | 5 | 1996–2001/6.2 | 50–65 | F | 390/1,249,670 | Cancer registry | Self-reported | Age, height, strenuous exercise, socioeconomic level, smoking, alcohol intake, parity, age at first birth, OC |
| Johnson,2011 | 1 | 1986–2004/10.5 | 55–85.7 | F | 125/291,021 | Medicare data | Self-reported | Age. |
| Michaud, 2011 | 2–11 | 1991–2004/8.4 | 35–70 | M/F | 203/380,775 | Cancer registry | Self-reported, Measured | Age, country, sex, education. |
| Wiedmann,2013 | 4 | 1984–1986/23.5 | ≥20 | M/F | 81/74,242 | Cancer registry | Measured | Age, sex |
| Case-control studies | ||||||||
| Claus,2013 | 1 | 2006–2011 | 29–79 | F | 1,127/1,092 | Cancer registry | Self-reported | Age, sex, residence, race, education, menopause status, age at menopause, age at menarche, smoking, alcohol use, breastfeeding, OC, HRT, number of FLB, age at FTP. |
| Custer,2006 | 1 | 1995–1998 | ≥18 | F | 143/286 | Pathology reports | Self-reported | Age, race, marital status |
M, male; F, female; OC, oral contraceptive; HRT, hormone replacement therapy; FLB, first live birth; FTP, full-term pregnancy.
a
Studies were conducted in: (1) USA, (2) Sweden, (3) Denmark, (4) Norway, (5) United Kingdom, (6) France, (7) Netherlands, (8) Spain, (9) Italy, (10) Germany, (11) Greece.