Table 3. Risk of ovarian cancer by parity using generalised estimating equations and conditional logistic regression among women in the Breast Cancer Family Registry.

	Conditional logistic		GEE		GEE
	Cases with unaffected sister controls		Cases with unaffected sister controls		All cases and all controls
	Age-adjusted model	Multivariable modela	Age-adjusted model	Multivariable modelb	Multivariable modelc
	OR (95% CI)	OR (95% CI)	OR (95% CI)	OR (95% CI)	OR (95% CI)
No. of full-term births
0	Ref	Ref	Ref	Ref	Ref
1	1.58 (0.45, 5.53)	1.23 (0.23, 6.45)	1.52 (0.53, 4.42)	1.21 (0.30, 4.97)	1.64 (0.96, 2.81)
⩾2	0.97 (0.35, 2.65)	0.50 (0.12, 2.12)	1.21 (0.63, 2.34)	0.96 (0.40, 2.27)	2.30 (1.52, 3.48)
Age at first birth (years)
Nulliparous	Ref	Ref	Ref	Ref	Ref
<22	0.97 (0.31, 3.11)	0.62 (0.13, 3.01)	1.27 (0.61, 2.62)	0.82 (0.31, 2.15)	2.72 (1.76, 4.20)
22–27	1.20 (0.41, 3.46)	0.67 (0.15, 2.92)	1.38 (0.67, 2.87)	1.00 (0.40, 2.55)	2.30 (1.49, 3.53)
>27	1.05 (0.31, 3.56)	0.70 (0.14, 3.37)	1.04 (0.48, 2.25)	1.22 (0.42, 3.52)	1.40 (0.86, 2.27)
Breastfeeding
Never	Ref	Ref	Ref	Ref	Ref
Ever	0.77 (0.31, 1.94)	1.72 (0.54, 5.43)	0.86 (0.50, 1.49)	1.57 (0.77, 3.20)	0.81 (0.61, 1.06)

Abbreviations: CI=confidence interval; GEE=generalised estimating equation approaches; OR=odds ratio.

^aAdjusted for age, breastfeeding, age at menarche, height.

^bAdjusted for age, oral contraceptive use, age at first birth, age at last birth, breastfeeding, age at menarche, height.

^cAdjusted for age, oral contraceptive use, age at first birth, breastfeeding.