Table 3 Summary of meta-analysis results for case-case analyses (Reference group: Luminal A; n = 18 studies)

Age at menarche (n = 13)

Later vs. earlier

NS + 

NS + 

NS-

Age at menopause (n = 6)

Later vs. earlier

–

NS + 

NS-

Menopausal status (n = 7)

Post vs. pre/peri

NS + 

S + 

S + 

Age at first birth (n = 12)

Nulliparous/later vs. earlier age at FB

NS-

S-

S-

Parity (n = 16)

Higher parity vs. low/nulliparity

NS + 

NS + 

S + 

Breastfeeding (n = 10)

Ever /longer vs. never/shorter

NS-

NS-

S-

OC use (n = 9)

Ever/longer vs. never/shorter

S-

NS + 

NS + 

HRT (n = 5)

Ever vs. never

NS-

NS + 

NS +