The sponsored study with a relative risk of 1.5 has been reanalysed several times, yielding lower relative risks; after this failed to convince, a new reanalysis was sponsored by another company.

One sponsored study finding an increased risk has not been published.

Vandenbroucke JP, Helmerhorst FM, Frits R Rosendaal FR. Competing interests and controversy about third generation oral contraceptives. BMJ 2000; 320: 381.