Do young women with unexplained infertility show manifestations of decreased ovarian reserve?

Purpose: To investigate whether unexplained infertility at a young age demonstrates manifestations of decreased ovarian reserve.
Methods: A total of 100 women were divided into two equally sized groups. The study group comprised women aged ≤ 37 years diagnosed with unexplained infertility, and the control group included age-matched women with either mechanical factor or severe male factor infertility.
Results: Both groups were comparable in their basic characteristics. Overall, women with unexplained infertility presented with inferior ovarian reserve results set against women of the control group. The number of ≥ 14-mm follicles on the day of hCG administration was significantly lower in the study compared with the control group (7.0 ± 4.5 vs. 10.4 ± 4.1 follicles, respectively, P < 0.001). Likewise, basal serum FSH was higher in the study compared with the control group (8.4 ± 5.5 vs. 6.4 ± 1.7 IU/L, respectively, P = 0.015), while antral follicle count was lower (10.9 ± 6.6 vs. 16.2 ± 6.6 follicles, respectively, P < 0.001). Furthermore, women with unexplained infertility required a higher total dose of FSH for ovarian stimulation (2,923 ± 1,701 vs. 2,196 ± 941 IU/L, respectively, P = 0.010), but exhibited a lower number of retrieved oocytes (9.3 ± 6.3 vs. 15.6 ± 7.9 oocytes, respectively, P < 0.001), alongside a lower number of achieved embryos (5.3 ± 4.0 vs. 8.0 ± 4.7 embryos, respectively, P = 0.002). Interestingly, the cumulative clinical pregnancy rate was not significantly different between the two groups (44% vs. 58%, respectively, P = 0.163).
Conclusions: Young women ≤ 37 years of age with unexplained infertility have clear manifestations of sub-optimal ovarian reserve set against controls. Our findings suggest that unexplained infertility at a young age may be a risk factor for developing poor ovarian response, specifically as a quantitative, rather than a qualitative, risk factor.