Table 4.

 The risk of venous thrombosis associated with different doses of ethinylestradiol in monophasic oral contraceptives. Data are odds ratios adjusted for age (95% CI) unless stated otherwise

Ethinylestradiol dose (μg)	Percentage use among controls*	Levonorgestrel	Gestodene	Desogestrel
20	11.2	1.1 (0.4 to 3.1)	0.3 (0.2 to 0.7)	0.7 (0.4 to 1.2)
30†	84.4	1	1	1
50	4.4	2.2 (1.3 to 3.7)	—	—

*In total, 51 women used a monophasic preparation with 20 μg ethinylestradiol, 385 women used one with 30 μg, and 20 used one with 50 μg (total 456).

†Reference category is the most commonly used dose of oestrogen among controls.