(Disclaimer: This article is for scientific use only, and the information in the following content has been processed to protect patient privacy) Abstract: The patient underwent left adnexal resection for left ovarian junctional mucinous tumor with junctional cystic adenocarcinoma at the age of 17. The postoperative prognosis was good, but she developed infertility due to ovarian hypofunction and came for treatment. She was given a mild pro-ovulatory regimen and in vitro fertilization, and she successfully conceived and delivered. Basic information】Female, 25 years old 【Disease type】Infertility, ovarian hypofunction, right ovarian chocolate cyst, right ovarian flavin cyst 【Visiting hospital】Shanghai Tenth People’s Hospital 【Visiting time】December 2020 【Treatment plan】Mild ovulation promotion (injectable urotropin, letrozole tablets) + in vitro fertilization 【Treatment cycle】In vitro ovulation for 8 days, transplantation 2 months after egg retrieval 【Treatment result The patient was a 25-year-old woman who came to our hospital because she had no contraception after marriage but had not conceived for one year. The patient described that she had undergone left adnexal resection for junctional mucinous tumor of the left ovary with junctional cystic adenocarcinoma when she was 17 years old and had 4 cycles of chemotherapy after surgery. Her usual menstrual cycle is 28 days, about 7 days at a time, with medium volume. She is 158 cm tall, weighs 63 Kg, BMI 25.2, and underwent an outpatient examination with ultrasound findings: 3 right sinus follicles, left ovarian agenesis, and generally normal semen in the male partner. Basal sex hormones: FSH/LH: 2.06/0.77IU/L; T: 1.51ng/ml; AMH: 1.45ng/ml: Ca125: 20.57U/mL. Gynecologic ultrasound suggested: right ovarian chocolate cyst and right ovarian flavin cyst. Preliminary diagnosis: infertility, ovarian hypofunction, right ovarian chocolate cyst, right ovarian flavin cyst. (Gynecologic ultrasound) II. Treatment history Considering that the patient was a young tumor patient, although there were clear indications for IVF treatment, it was difficult to predict whether the high estrogen levels during IVF would have adverse effects on the patient’s ovarian tumor. In order to minimize the effects of the drugs, after communication with the patient, a mild stimulation protocol was chosen for IVF induction, using drugs such as injectable urotropin and adjuvant letrozole tablets for the whole induction cycle to reduce the estrogen level throughout the induction cycle. A total of 8 days of ovulation were used to retrieve 6 mature eggs, which were fertilized in vitro and 2 quality embryos were frozen. The patient was not scheduled for fresh embryo transfer because the ultrasound showed a 10-mm thickness of the endometrium and the echogenicity was not uniform. One month after egg retrieval, on the 4th day of menstruation, hysteroscopy was scheduled to detect endometrial polyps and remove them surgically. In the second month after egg retrieval, one embryo was prepared for endometrial transfer in the natural cycle protocol in order to reduce hormone dosage, and conception was successful. The patient was a tumor patient and the ovulation regimen might affect the tumor, so she chose a mild stimulation ovulation regimen. After ovulation, 6 mature eggs were successfully retrieved and 2 high-quality embryos were finally frozen. In the second month after egg retrieval, in order to reduce hormone dosage, the natural cycle protocol was prepared for endometrial transfer of one embryo. 12 days after transfer, the HCG was 729.0 mIU/ml, and after seeing the fetal heart, she was monitored by the obstetrics department of the local hospital for labor and delivery, and a cesarean section was performed at 33+6 weeks of gestation due to low amniotic fluid. The patient needs to pay attention to the following points: 1. Take rest in the last few days after receiving treatment and do not exercise strenuously to avoid abdominal discomfort; 2. If abdominal discomfort, distension and stabbing pain occur, it is necessary to consult a doctor in time for a clear diagnosis. V. Personal insight Discovering tumor is a great blow to individuals and families, and most patients think of life first. With the development of medicine, the early screening, early detection and early treatment of tumor have been promoted, along with the emergence of new therapies and new drugs, the cure rate and survival rate of tumor patients have been improved, therefore, patients also have the demand for fertility. In this case, the patient was only 17 years old at the time of tumor surgery. After standardized treatment, the patient was well controlled and naturally had the desire to have children, so choosing the appropriate treatment plan to help the patient improve the safety of childbirth is a reflection of technology and humanistic care. In recent years, the focus of the industry has shifted to giving patients fertility preservation before treatment for the first onset of tumor, such as freezing semen before chemotherapy for men and freezing ovarian tissue or follicles before surgery or radiotherapy for women.