Menstruation is the abscission of the endometrium with bleeding that accompanies the cyclic changes of the ovaries, and the establishment of regular menstruation is a sign of maturing reproductive function. The mechanisms of endometrial changes during menstruation mainly include the vasoconstriction hypothesis, the inflammatory response hypothesis and the tissue destruction hypothesis.Rhythmic contraction and diastole of the endothelial spiral arteries during the 24 hours before menstruation, resulting in ischemic necrosis and exfoliation of the distal vessel walls and tissues.Endometrial epithelial repair begins on day 2 of menstruation, and this phase is non-estrogen-dependent. On day 6, estrogen receptors and progesterone receptors in the endometrium are highly expressed, and the endometrium begins to enter an estrogen-dependent proliferative state.So the length of a woman's period may be influenced by many factors, including genetics, endocrine disorders, uterine and ovarian abnormalities, immune regulation, etc.As normal ovarian reserve women,is there a correlation between the length of menstrual periods with women's ovarian reserve function or IVF pregnancy outcome excluding uterine disease and genetics during the nearly 400 menstrual periods? Are there regulatory factors for scar-free endometrial repair that improve the uterine microenvironment and thus drive our research on endometrial tolerance and thin endometrium?
Currently, anti-Mtillerian hormone (AMH), basal estradiol (E2), follicle-stimulating hormone (FSH), basal luteinizing hormone (LH), and sinus follicle (AFC) are commonly used to assess ovarian function. AMH is secreted by the granulosa cells of the sinus follicles and antral follicles of the ovary, which does not change with the menstrual cycle and has become a stable indicator for clinical testing in recent years.It is worth mentioning that although in patients with normal AMH, the low-response population still exists and is more likely to be ignored, so it has been suggested that basal FSH/LH may have a new predictive value for the assessment of Gn sensitivity and ovarian reserve function in IVF protocols.Kofinas Jason Dargued that as FSH/LH values increase, the patient's ovarian reserve function and IVF cycle success rates decrease accordingly.Liang Xbelieved that FSH/LH was significantly higher in patients who cancelled their IVF cycles compared to those who did not.In this retrospective study, it was found that patients with >4 days of menses had lower FSH/LH (2.60 (1.80-3.58) vs. 3.57 (2.58-8.33), p<0.05) and higher AMH (2.25 (1.18-3.83) vs. 1.73 (1.12-3.17), p<0.05) .We deduce that ovarian reserve function may be better in patients with >4 days of menstruation than in patients with ≤4 days of menstruation, as shown by the fact that in patients with ≤4 days of menstruation during in vitro fertilization, the initiation dose (bottles) (4 (3-4) vs 3 (2-4), p<0.05), total Gn dose(bottles) (36.00 (28.00-40.00) vs 32.00 (24.92-40.00), p<0.05) were significantly more than in patients with >4 days of menstruation,While the number of eggs obtained (7.00 (5.00-10.00) vs. 8.00 (6.00-11.25), p<0.05), MII (7.00 (4.00-10.00) vs. 8.00 (5.00-11.00), p<0.05), 2PN (4.00 (3.00-6.00) vs. 5.00 (3.00-8.00 ), p < 0.05) lower than patients with periods >4 days.This finding is possibly related to the higher FSH/LH ratio found by Arat Ö, where patients obtained fewer mature oocytes.It has been suggested that elevated FSH/LH may reduce the success of the patient's final cycle.However, in this study, despite the statistical significance of clinical pregnancy, biochemical pregnancy, and non-pregnancy between the different groups (p=0.027 <0.05), due to the correlation coefficient r=0.115, it indicates that the association between the length of menstruation and pregnancy outcome is weak. And when it comes to complications in pregnant women, mode of delivery and postpartum fetal condition, no differences were found between the two groups for length of menstruation.
With the development of ART technology, although the improvement in the type of drugs used to promote ovulation has ensured that we have a significant number of eggs and good quality embryos, we are still lagging behind in improving the pregnancy rate significantly.Al Chami A believes that the key factors affecting the success of ART are 1/3 from the embryo and 2/3 from the endometrium.In recent years, research in the reproductive community has focused on endometrial receptivity, which refers to the ability of the endometrium to accept embryos, and on the search for the "window of implantation" (WOI), which refers to the optimal time to allow embryo implantation followed by pregnancy.It has been found that a decrease in endometrial blood flow may affect the growth of the uterine glandular epithelium, leading to a decrease in the expression of endothelial vascular endothelial growth factor in the endometrium.Reduced expression can lead to damage to the endometrial vascular system, decreasing the endometrial blood supply and causing endometrial growth restriction to form a thin endometrium, which is clinically manifested by shorter menstrual periods and reduced menstrual flow.It has been suggested that these factors that modulate the uterine glandular epithelium and small spiral arteries include endothelium-derived vasodilatory factors (endothelin ET, NO), vascular endothelial growth factor (VEGF), interferons, tumor necrosis factor, platelet-derived growth factor, and transforming growth factor.Another type of disease that presents as shorter periods and reduced menstrual flow is uterine adhesions. Some scholars used in vitro cell culture techniques to embryo the clone formation rate of stem cells from menstrual blood of patients with severe uterine adhesions and patients in the normal endometrial group, and found that there were significantly more endometrial stem cells in the normal control group than in patients with severe uterine adhesions.In this retrospective study, it can be found that patients with periods ≤4 days, patients with periods >4 days had thicker endometrial thickness at the day of transplantation (9.10 (7.60-10.10) vs. 10.80 (9.50-12.30), p < 0.05), while clinical pregnancies and biochemical pregnancies with periods >4 days were higher than those with periods ≤4 days (169 (38.2%) vs. 34 ( 33.0%)), (59(13.3%) vs 6(5.8%)), and non-pregnant patients with periods ≤4 days were higher than those with periods >4 days (63(61,.2%) vs 214(48.4%)), leading us to associate whether the length of periods is related to the number of endometrial stem cells.In recent years, some scholars have discovered that endometrial stem cells can be released into menstrual blood during menstruation as the endometrium collapses and sheds, allowing scientists to focus on menstrual blood-derived endometrial stem cells, which are stem cells with proliferative and multidirectional differentiation potential isolated from menstrual blood. Some scholars have established a nude mice model of endometrial injury by mechanical method and demonstrated that endometrial stem cells from menstrual blood can survive intrauterine transplantation, while the pregnancy rate in the transplanted endometrial stem cell group was significantly higher than that in the control group[24-25].It is suggested that intrauterine implantation of transgenic endometrial stem cells may improve the embryonic implantation function of the damaged endometrium and thus increase the pregnancy rate. In a retrospective analysis of the mode of delivery and pregnancy complications, it was found that cesarean delivery was more common in both groups compared to vaginal delivery [15 (12.93%) vs 6 (19.35%), 101 (87.07%) vs 25 (80.65%), 0.364], although there was no statistical difference, probably because IVF pregnancy is more "precious". compared to this bias may be related to the fact that IVF women are more likely to deliver by cesarean section than women who deliver with normal pregnancy,the obstetricians may take the patient's wishes into account more. There were no statistical differences between the two groups for ectopic pregnancy, early miscarriage, late miscarriage, or the number of weeks of labor, infant length, or infant weight after follow-up delivery.
From this retrospective study, it can be deduced that the sensitivity of patients with <4 days of menstruation to pro-ovulatory drugs, the number of eggs obtained by pro-ovulation, the thickness of the endometrium on the transplantation day, and the pregnancy outcome (clinical pregnancy, biochemical pregnancy) are lower than those with ≥4 days of menstruation during IVF. However, the antagonist regimen used in this retrospective analysis, whether the results remain the same in other IVF regimens requires further accumulated clinical data analysis, and finally, the association between menstrual length and female endocrine needs to be explored and studied in more prospective clinical studies and at the basic molecular protein level.