Oral contraceptives and increased formation of soluble fibrin.

Soluble fibrin was measured weekly for two months in 12 normal women and in 12 women on combined oestrogen-progestogen therapy (Ortho-Novin, Norinyl, Enavid, Ovral, Ovulen, Demulen). Plasma soluble fibrin concentration in women on oral contraceptives showed an increase of 97.2% (P <0.001) above that of normal women. In three cases, where each woman on the oral contraceptive served as her own control, stopping medication led to a return to normal of the plasma content of soluble fibrin.