Endometrial receptivity (ER) refers to the ability of endometrium (uterine lining) to accept embryos for implantation which is a critical step to get pregnant. ER changes with the menstrual cycle. There are only a few days in the menstrual cycle when uterine lining is good enough to accept embryos implantation. This is implantation window generally 6-10 days after ovulation, which is the 20th to 24th day of the normal menstrual cycle. Studies have shown that low pregnancy rate is closely related to the thin endometrium. If the average size of the follicles reaches 18 mm and the endometrial thickness is < 7.0 mm, embryo implantation will be greatly affected. Clinically, higher quality embryos can usually be transferred, but only a few embryos can be successfully implanted in the IVF-ET cycle. Studies have shown that up to 75 % of pregnancy losses are due to implantation failure. Studies have confirmed that 2/3 of IVF-ET implantation failures are due to low endometrial receptivity (ER). Therefore, improving ER is the key to get pregnant naturally or via IVF by increasing the IVF-ET pregnancy rate.
Thin endometrium is one of the most important factors for low ER, Thin endometrium refers to the thickness of the endometrium in the middle luteal phase (after ovulation) of 6–10 days is < 7.0 mm. Studies have shown that low pregnancy rate is closely related to the thin endometrium. If the average size of the follicles reaches 18 mm and the endometrial thickness is < 7.0 mm, embryo implantation will be greatly affected. clinical studies have found that endometrium with a thickness of more than 8 mm is more suitable for embryo implantation and development. Endometrial thickness, endometrial pattern and endometrial blood supply are closely related to embryo implantation. Study suggested that increasing the uterine blood flow and endometrial thickness has positive significance for improving ER and has a positive effect on embryo implantation rate and clinical pregnancy rate. Though great improvement has been achieved in embryo quality, little progress has been made for improvement of poor quality of ER over three decades after the introduction of IVF.
As an effective non-drug therapy, acupuncture has been chosen by many infertile couples as a treatment.
Can acupuncture improve endometrial receptivity?
A recent study reviewed the evidence of randomized controlled trials (RCTs) using acupuncture to improve endometrial receptivity (ER). 3041 patients were included in the analysis. They found some evidence that acupuncture may improve pregnancy rate, and embryo transfer rate and the thickening of endometrium.
A recent review analysed all data of 14 trials with 1564 women participants from inception to 26 February 2022 to investigate the dose-related efficacy of acupuncture for endometrium receptivity.
They found that acupuncture treatment for 2 or 4 days only did not improve uterine blood flow, ER or pregnant rate. Acupuncture treatment for one menstrual cycle significantly increased uterine blood flow, endometrial (uterine lining) thickness and ER and has higher pregnant rate compared to control group. Acupuncture treatment for three cycles significantly increased more in uterine blood flow, endometrial (uterine lining) thickness and ER and has higher pregnant rate compared to control group.
References
Xiaoyan Zheng, et al Front Public Health. 2022; 10: 858587
Yajing Zhong et al BMC Complement Altern Med. 2019; 19: 61.
