A Phase III Clinical Study of Jinpei Growth Hormone Injection in the Treatment of Short Stature Children With Small for Gestational Age (SGA)

Inclusion Criteria: * Clinical diagnosis of small for gestational age (SGA), with birth certificate or discharge record; gestational age ≥28 weeks; birth weight and/or length below the 10th percentile (P10) for sex and gestational age. * Age ≥3 years at the time of informed consent (calculated from birth date on birth certificate/ID). * Prepubertal boys and girls (Tanner stage I). * Screening height \< -2 SD of normal height reference values for same sex and chronological age. * Screening bone age \< chronological age + 1 year (bone age X-ray within 6 months before screening acceptable). * No prior treatment with growth hormone, IGF-1, or insulin-like secretagogues. * Subject and guardian able to voluntarily sign informed consent form (ICF) and comply with study procedures; for subjects without civil capacity, guardian's written informed consent required, with subject assent when possible. Exclusion Criteria: * Hypersensitivity to growth hormone class drugs or their excipients. * Suspected or confirmed pediatric growth hormone deficiency (GHD) requiring GH stimulation testing (GH peak \>7 ng/mL excludes GHD). * Known chromosomal or gene mutations affecting growth, or known syndromes including but not limited to GHD, Turner syndrome, Laron syndrome, Noonan syndrome, Prader-Willi syndrome, Silver-Russell syndrome, skeletal dysplasia, SHOX gene abnormalities. * Any known or suspected disease/condition that may cause short stature and may interfere with endpoint evaluation, including but not limited to chronic kidney disease, diabetes, skeletal dysplasia (with family history), severe spinal abnormalities, malnutrition, hypothyroidism, immunodeficiency. * Current signs/symptoms of increased intracranial pressure, active proliferative retinopathy, or history of slipped capital femoral epiphysis or intracranial hypertension. * Cognitive impairment, neurodevelopmental disorder or psychiatric illness that may interfere with endpoint evaluation. * Current intracranial tumor, hematologic malignancy or other malignant tumor (regardless of treatment); family history of tumor or high tumor risk (e.g., Bloom syndrome, Fanconi syndrome, Down syndrome). * Positive HBsAg at screening; history or diagnosis of hepatitis C, HIV infection or tuberculosis. * Abnormal screening laboratory values considered by investigator to interfere with safety evaluation (ALT \>1.5×ULN; creatinine \>1.5×ULN). * Screening indicates impaired fasting glucose, impaired glucose tolerance or diabetes. * Systemic corticosteroid treatment within 3 months before screening (\>28 days cumulative or \>14 days continuous). * Prior use of aromatase inhibitors, GnRH analogs, sex hormones, protein anabolic drugs, or other drugs affecting growth and development. * Unable to receive subcutaneous injections (e.g., anticoagulant therapy, bleeding disorders, idiopathic thrombocytopenic purpura). * Claustrophobia or inability to undergo head MRI. * Participation in other clinical trials within 3 months before screening. * Other conditions considered by investigator unsuitable for enrollmen.