The randomized, placebo-controlled multicenter trial is conducted in five centers in China. After screening and obtaining the signed informed consent , the participants are randomly divided into three groups: acupuncture group (Acu.+IVF），sham acupuncture group（Sham Acu. +IVF），and the control group (only IVF).
Married women aged 25-40;
Repeated implantation failure for unknown reasons (experienced 2 or more embryo transfers of good-quality embryos without achieving clinical pregnancy);
Transplantable Day 3 high-quality frozen embryos or frozen blastocysts (≥3BB);
Estrogen and progesterone replacement therapy (HRT), endometrial thickness ≥7mm on the day of endometrial transformation.
Those who prepare for PGD;
Recipients of egg donors;
Chromosomal abnormalities in both or one of the couples (excluding chromosome polymorphism);
patients with implantation failure due to known embryonic factors;