A meta-analysis on the correlation between ovarian activity and the incidence of intermenstrual bleeding during low-dose oral contraceptive use.

We aimed to evaluate potential correlation between ovarian activity during use of combined oral contraceptives and the incidence of intermenstrual bleeding. Data from seven prospective clinical studies with five different combined low-dose oral contraceptives were retrospectively analyzed to determine ovarian activity measured by the Hoogland Score (follicle diameter and endogenous hormone levels) and cycle control. A total of 227 young fertile women were evaluated over three treatment cycles each. Women with intermenstrual bleeding had statistically significantly higher estradiol levels than those without intermenstrual bleeding. Also, women with intermenstrual bleeding had significantly larger follicle-like structures than those without intermenstrual bleeding. For example, in the second treatment cycle the difference of the mean follicle diameters between women without intermenstrual bleeding (12.5 mm) and women with spotting (16.9 mm) or breakthrough bleeding (16.1 mm) was statistically significant (p = 0.0179). Less than 17% of women with Hoogland Score 1, 2 or 3 (low ovarian activity) reported intermenstrual bleeding. On the other hand, 35.2% of women with Hoogland Score 4 (active follicle-like structures) reported intermenstrual bleeding. The association between bleeding and Hoogland Score was statistically significant (p < 0.0011). The findings of this retrospective analysis provide evidence that high ovarian suppression is positively correlated with improved cycle control in terms of less frequent intermenstrual bleeding - slight and heavy.