The relationship between ovarian
hormones and
bleeding patterns during continuous
progestin contraception was studied in 29 women who used
Nestorone (NES) releasing implants.
Oestradiol and
progesterone were measured in blood samples taken twice a week for 6 consecutive weeks, during months 6, 12, 18 and 24 of implant use. Retrospectively, the association between hormonal concentrations and
bleeding patterns was evaluated. Twenty-four short (</= 24 days), 36 normal (25-35 days), 27 long (36-90 days) and nine episodes of amenorrhoea, as well as 28 periods of prolonged
bleeding, were identified. Short cycles, periods of prolonged
bleeding and amenorrhoea were characterized by low
oestradiol concentrations.
Bleeding after a normal or long cycle regularly occurred after a rise and fall of
oestradiol or
oestradiol and
progesterone. The duration of
bleeding was directly and significantly associated with the highest concentration of
oestradiol in the previous 15 days in anovulatory cycles. Luteal activity was associated with shorter duration of
bleeding. Periods of prolonged
bleeding were usually initiated with a drop in
oestradiol and over half ended with an increase in
oestradiol. It was concluded that changes in endogenous
hormone have a significant influence over the
bleeding pattern during use of NES implants.