Does corpus luteum locally affect follicular growth negatively?

In this study bilateral ovarian follicular growth during the luteal phase was investigated in relation to the ovary where ovulation occurred. The diameter of the largest follicle in the contralateral ovary without corpus luteum and in the ipsilateral ovary with corpus luteum was measured using vaginosonography in a total of 66 natural cycles of 27 normally cycling women undergoing treatment with intrauterine insemination (IUI). None of the women received ovarian stimulation or luteal support. Follicles from 2 to 11 mm in diameter were measured in early luteal phase (day +1 to +4), mid-luteal phase (day +5 to +9) and late luteal phase (day +10 onwards). The mean diameters of the largest follicle in the contralateral ovary without corpus luteum during the early, mid- and late luteal phases were 6.81 +/- 1.33 (mean +/- SD), 6.14 +/- 1.29 and 5.71 +/- 1.17 mm respectively, while those of the ipsilateral ovary with corpus luteum were 6.48 +/- 1.40, 5.65 +/- 1.47 and 4.98 +/- 1.19 mm respectively. While there was no significant difference during the early luteal phase, the mean diameter of the largest follicle in the ipsilateral ovary with corpus luteum was significantly smaller than that of the contralateral ovary without corpus luteum during the mid-luteal phase (P < 0.004) and the late luteal phase (P < 0.0005). These results indicate that the corpus luteum locally affects neighbouring follicular growth negatively during the luteal phase of the menstrual cycle, with the most pronounced effect expressed in the mid- and late luteal phases.