Table 2

Reproductive factors in women and risk of rheumatoid arthritis, Denmark 1998 to 2003

Number of patients/controls

ORa (95% CI)


Age at menarche

≤12 years

85/145

1 (ref)

13 years

84/130

1.08 (0.73 to 1.61)

14 years

88/105

1.39 (0.93 to 2.08)

≥15 years

94/80

1.87 (1.23 to 2.85)

Trend test (p)

0.002

Number of live-born children

0

67/86

1 (ref)

1

81/85

1.10 (0.67 to 1.79)

2

133/196

0.76 (0.48 to 1.21)

3

63/84

0.81 (0.48 to 1.37)

≥4

21/27

0.73 (0.36 to 1.51)

Trend test (p)

0.15

Spontaneous abortion

Never

237/292

1 (ref)

Ever

78/120

0.83 (0.59 to 1.18)

Test for homogeneity (p)

0.29

Breastfeedingb

Never

19/18

1 (ref)

Ever

279/374

0.70 (0.35 to 1.39)

Test for homogeneity (p)

0.30

Age at menopausec

<50 years

37/34

1 (ref)

≥50 years

47/49

0.87 (0.46 to 1.65)

Test for homogeneity (p)

0.68

Oral contraceptive pills

Never

116/165

1 (ref)

Ever

249/312

1.24 (0.91 to 1.71)

Test for homogeneity (p)

0.18

Hormone replacement therapyd

Never

328/436

1 (ref)

Ever

36/37

1.08 (0.63 to 1.86)

Test for homogeneity (p)

0.78


Due to missing values for some individuals, numbers do not always add up to 366 patients and 478 controls. aAdjusted for birth year and year or pseudo-year of RA diagnosis. bAmong women with at least one child. cAmong postmenopausal women without histories of hormone replacement therapy or surgical removal of the uterus or ovaries. dAmong women age 45 years or older. CI, confidence interval; OR, odds ratio; ref, reference.

Pedersen et al. Arthritis Research & Therapy 2006 8:R133   doi:10.1186/ar2022

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