Table 5.

RRs of breast cancer in nulliparous, respectively parous women, according to use of fertility drugs

Fertility drugNulliparous women
Parous women
Interaction P
No. cases/no. in subcohortRR* (95% CI)No. cases/no. in subcohortRR* (95% CI)
Gonadotrophins
    Never118/3531.00177/7081.00
    Ever23/771.69 (1.03-2.77)13/880.84 (0.46-1.54)0.07
Clomiphene
    Never92/2761.00137/5451.00
    Ever49/1541.18 (0.82-1.68)53/2511.05 (0.75-1.45)0.63
hCG
    Never97/2851.00140/5461.00
    Ever44/1451.07 (0.74-1.54)50/2500.88 (0.63-1.22)0.42
GnRH
    Never131/3741.00182/7541.00
    Ever10/561.12 (0.56-2.23)8/421.67 (0.75-3.70)0.44
Progesterone
    Never137/4241.00186/7891.00
    Ever4/63.24 (1.13-9.35)4/73.49 (1.25-9.77)0.92
  • NOTE: All analyses were stratified according to calendar year (in categories) and age at start of follow-up (in categories).

  • * RRs adjusted for childbirth (ever/never), and number of additional births (linear).

  • Follicle-stimulating hormone and human menopausal gonadotrophin.