Baseline characteristics of patients with NOR, DOR-Path, and DOR-Phy

Eighty-five patients were recruited for this study and stratified into three groups based on age and ovarian reserve status: two experimental groups (DOR-Path, n = 25 and DOR-Phy, n = 33) and a control group (NOR, n = 27). Detailed baseline characteristics are presented in Table 1. Parameters such as average age, BMI, duration of infertility, serum hormone levels and infertility factors were compared among the groups. The results showed that, as expected, significant differences emerged between the DOR-Path and NOR groups in bFSH, AFC, AMH. However, no significant differences were noted in age, BMI, infertility duration, bLH, bE2, and P. Similarly, comparisons between the DOR-Phy and NOR groups highlighted significant differences in age, bFSH, AFC and AMH. Conversely, BMI, infertility duration, bLH, bE2, and P showed no significant differences. In the comparison between DOR-Path and DOR-Phy groups, significant differences were observed in age, bFSH, and AMH. However, no significant differences were found in BMI, infertility duration, bLH, bE2, P and AFC. The findings illustrate substantial variations in negative predictors (age, bFSH) and positive predictors (AFC, AMH) linked to physiological ovarian reserve hypoplasia in comparison to the NOR group. Likewise, considerable differences in negative predictors (bFSH) and positive predictors (AFC, AMH) were observed concerning pathological ovarian reserve hypoplasia.

Table 1 The baseline characteristics of patients with NOR, DOR-Path and DOR-PhyMelatonin levels in patients with DOR-Path, DOR-Phy and NOR

To comprehensively evaluate melatonin level variations among patients with DOR-Path, DOR-Phy, and NOR, we conducted ELISA assays on samples of patient serum (base serum and hCG day serum) and follicular fluid collected on the day of oocyte retrieval. Figure 1 illustrates the outcomes. Analysis of melatonin levels in base serum re-vealed a significant decrease (P < 0.05) in both the DOR-Path and DOR-Phy groups com-pared to the NOR group. However, no notable difference was observed between the DOR-Path and DOR-Phy groups. The values were 183.26 ± 43.90 (pg/mL) for the NOR group, 149.63 ± 43.78 (pg/mL) for the DOR-Path group, and 149.30 ± 37.88 (pg/mL) for the DOR-Phy group (Fig. 1a). Examination of melatonin levels in hCG day serum indicated no significant differences among patients in the DOR-Path, DOR-Phy, and NOR groups (Fig. 1b). Conversely, the analysis of melatonin levels in follicular fluid showcased the lowest levels in the DOR-Path group and the highest in the NOR group. Significant differences were evident between both the DOR-Path (145.43 ± 39.30 pg/mL) and DOR-Phy groups (162.30 ± 59.66 pg/mL) when compared with the NOR group (236.84 ± 55.26 pg/mL) (P < 0.001) (Fig. 1c).

Subsequently, we conducted an analysis of melatonin levels in volunteers categorized into distinct groups. Comparisons of melatonin levels in serum and follicular fluid at different stages indicated the highest levels in follicular fluid and the lowest in hCG day serum (Fig. 1d–f). Noteworthy differences in melatonin levels were observed within the NOR group: significant disparities between base day serum and follicular fluid (P < 0.001), as well as between hCG day serum and follicular fluid (P < 0.001) (Fig. 1d). However, no significant difference emerged in melatonin levels between serum on the base day and hCG day. The values were 183.26 ± 43.90 (pg/mL) for the base serum, 164.03 ± 55.78 (pg/mL) for the hCG day serum, and 236.84 ± 55.26 (pg/mL) for the follicular fluid (Fig. 1d). In contrast, the melatonin levels within each sample in the DOR-Path and DOR-Phy groups exhibited no significant differences between them (Fig. 1e, f).

These findings indicate distinct melatonin level variations in the base serum and follicular fluid among patients with DOR-Path, DOR-Phy, and NOR. Particularly note-worthy are significantly lower melatonin levels in the DOR-Path and DOR-Phy groups compared to the NOR group in follicular fluid.

Fig. 1

Melatonin Levels in NOR Group, DOR-Path Group, and DOR-Phy Group. (a) Compared with the control subjects (n = 27), base serum melatonin levels were reduced in patients with DOR-Path (n = 25) and DOR-Phy (n = 33); (b) There were no significant differences in serum melato-nin concentrations on hCG day among NOR Group, DOR-Path, and DOR-Phy patients; (c) Com-pared with the NOR Group, Melatonin levels in the follicular fluid were reduced in patients with DOR-Path and DOR; (d) The melatonin levels of different specimens in NOR Group; (e) The melatinin levels of different specimens in DOR-Path patients; (f) The melatonin levels of different specimens in elderly DOR-Phy patients; When the P < 0.05, it indicates statistical significance

Comparative analysis of IVF outcomes in patients with DOR-Path, DOR-Phy, and NOR

Upon comparing IVF outcomes among the three groups, we noted that patients in the DOR-Path and DOR-Phy cohorts with low melatonin levels experienced inferior IVF outcomes. As illustrated in Table 2, there were significant disparities between the DOR-Path and NOR groups in variables such as the number of oocytes, oocytes/AFC, 2PN embryos, cleavage, day 3 usable embryos, and day 3 good quality embryos (P < 0.001). Similarly, the DOR-Phy group demonstrated comparable outcomes to the NOR group (P < 0.001). However, no statistically significant difference was found between the DOR-Path and DOR-Phy groups.

Table 2 Comparisons of IVF outcomes among patients with NOR, DOR-Path and DOR-PhyMelatonin levels in serum and follicular fluid can predict IVF outcomes

To delve deeper into the predictive role of melatonin in serum and follicular fluid regarding IVF outcomes, we examined the correlation between melatonin levels in serum and follicular fluid and the parameters of IVF outcomes. Our observations revealed a significant positive correlation between melatonin levels in serum and follicular fluid and the parameters of IVF outcomes (Fig. 2). The most robust correlations in follicular fluid melatonin levels with IVF outcome parameters (Fig. 2k-o) include the number of oocytes (rs=0.506, P < 0.001), cleavage (rs=0.552, P < 0.001), 2PN (rs=0.551, P < 0.001), day 3 usable embryos (rs = 0.483, P < 0.001), and day 3 good quality embryos (rs=0.586, P < 0.001). A relatively strong correlation was observed between melatonin levels in base serum and IVF outcome parameters (Fig. 2a-e), including the number of oocytes (rs=0.291, P = 0.007), cleavage (rs=0.338, P = 0.002), 2PN (rs=0.329, P = 0.002), day 3 usable embryos (rs=0.276, P = 0.010), and day 3 good quality embryos (rs=0.356, P = 0.001). Additionally, melatonin levels in hCG day serum exhibited a less pronounced correlation with IVF outcomes, but they remained significantly different (P < 0.05) (Fig. 2f-j), involving the number of oocytes (rs=0.232, P = 0.033), cleavage (rs=0.273, P = 0.012), 2PN (rs=0.258, P = 0.017), day 3 usable embryos (rs=0.241, P = 0.027), and day 3 good quality embryos (rs=0.316, P = 0.003). Based on the aforementioned results, melatonin levels in base serum, hCG day serum, and follicular fluid exhibit a significant positive correlation with IVF outcomes.

Fig. 2

Correlation between the melatonin levels in base serum and follicular fluid and IVF out-comes (n = 85). (a-e) Correlation between IVF outcomes and melatonin levels in base Serum; (f-j) Correlation between IVF outcomes and melatonin levels in hCG Day Serum; (k-o) Correlation between IVF outcomes and melatonin levels in follicular fluid; When the P < 0.05, it indicates statistical significance