Declined fertility and ovarian reserve in older women are associated with lower density of Growth hormone (GH) receptors and dysregulation in GH secretion. GH can regulate the expression of growth hormone receptor and strengthen the function of mitochondria, which could improve the quality of the female oocyte. In this study, a prospective randomized control will be conducted to explore the effect of GH adjuvant therapy on clinical outcome of in vitro fertilization.

Eligible subjects will be randomly assigned into either the study groups (receive somatropin co-treatment) or the control group (without sopmatropin treatment). Polyethylene glycol recombinant human somatropin will be injected weekly (3mg/per week) for approximately 6 weeks, i.e. from the beginning of preceding menstruation cycle until the day of ovum pickup. Both groups will receive a similar common protocol for ovarian stimulation. In vitro fertilization with or without intracytoplasmic sperm injection will be performed according to semen parameters. All embryos will undergo culture for blastocyst and the obtained blastocysts will be vitrified for deferred frozen embryo transfer. The Blastocyst formation rate will be the primary outcome measure.

Inclusion Criteria:

• 1)Married women between 35-40 years old; 2) serum AMH< 1.2ng/ml, and basal FSH<20IU/L during the screening period or within 6 months; 3) 18kg/m2≤BMI<30kg/m2; 4) Previous ART cycles <3.

Exclusion Criteria:

• 1）Gynecological diseases that affect pregnancy outcomes, such as submucous uterine myoma, intramural uterine myoma≥4cm, Ovarian cyst≥4cm, endometriosis, Uterine malformation, Tuberculosis of reproductive system; 2) Spontaneous abortion≥3 times; 3) Chromosomal abnormalities (except polymorphism) in one or both spouses; 4) Patients with well-defined and uncontrolled endocrine, metabolic, and adrenal diseases, such as diabetes, thyroid disease, Cushing's syndrome; 5) Patients with malignant tumors; 6) Previous use of somatropin products.

The study protocol and statistical analysis plan will be available online with publication. Data collected for the study, including specified data set and a data dictionary defining each field in the set, will be made available to others with publication.

After publication and for 1 year

Investigators can request data sharing by contacting the email of the corresponding author. Our publication committee established for this trial will review and approve the request.