Endometrial bleeding problems can be the major reason for discontinuing pro
gestin-only contraception, In this study the endometrial angiogenic respons
e in Norplant users was found to be lower than in women with normal menstru
al cycles. These disturbances in angiogenic response may be caused by oxida
nt-antioxidant imbalance in the endometrium. The aims of this study were to
investigate the effect of progestin-only contraceptives on blood concentra
tions of lipid peroxide and vitamin E, and the effect of vitamin E suppleme
ntation on endometrial angiogenic response in vitro. The subjects for this
study were Norplant users, depo-medroxy-progesterone acetate (DMPA) users,
and controls. Circulating lipid peroxide and vitamin E concentration was me
asured by routine methodology. Endometrial angiogenic response was assayed
using an endothelial cell migration assay. The results showed that the bloo
d concentrations of lipid peroxide from Norplant users with bleeding proble
ms were significantly higher than normal menstrual controls (P < 0.05) and
supplementation of vitamin E (in vitro) increased the endometrial angiogeni
c score. Blood concentrations of lipid peroxide were significantly increase
d (P < 0.05), and the blood concentrations of vitamin E were significantly
decreased (P < 0.05) after 3 months exposure to Norplant or DMPA, The endom
etrial angiogenic scores in Norplant and DMPA users were significantly lowe
r than in controls (P < 0.02). It is concluded that in progestin-only contr
aceptive users, higher lipid peroxide and lower vitamin E concentration may
cause endometrial cell damage and decrease the endometrial angiogenic resp
onse. It is suggested that vitamin E supplementation may counteract these u
nwanted side-effects.