Oestrogen/Progestogen Oral Contraception and Blood Clotting: A Long-term Follow-upBr Med J 1971; 4 doi: http://dx.doi.org/10.1136/bmj.4.5788.648 (Published 11 December 1971) Cite this as: Br Med J 1971;4:648
- L. Poller,
- Jean M. Thomson,
- Wendy Thomas
In a long-term study of women taking the combined oestrogen/progestogen oral contraceptives Ortho-Novin and Norinyl-1 the follow-up has been continued for three years and four years respectively.
Acceleration of both “intrinsic” and “extrinsic” clotting tests and of specific factor VII and X assays, reported previously at the nine-month stage, persisted throughout the period of study. Acceleration of Chandler's tube platelet aggregation and hypercoagulable thrombelastographic patterns were recorded. There was, however, no evidence of a cumulative effect after the first nine months.