To preliminary assess the efficacy and safety of recombinant human growth hormone injection on the treatment of small for gestational age (SGA), and determine the best dose.

Inclusion Criteria:

• Clinical diagnosis of small for gestational age, SGA.
• Chronological age between 2-6.5 years in girls and 2-7.5 years in boys. Both genders.
• Prepubertal stage (Tanner I).
• Without catch-up growth in two years after birth.
• Height was lower than the mean -2SD of the values of normal children of the same age and gender when participating in the study.
• A GH peak concentration >10µg/L in a provocative test within a year before participate in the study.
• Bone age<Chronological age+1.
• Normal glucose regulation：Fasting blood-glucose < 5.6mmol/L and 2-hour postprandial blood glucose< 7.8mmol/L.
• Gestational age≥Gestational age≥ 36weeks + 4days.
• Never accepted growth hormone treatment.
• The subjects and their guardians signed informed consent.

Exclusion Criteria:

• Subjects with Liver and renal insufficiency (ALT > 2 times of upper limit of normal value, Cr> upper limit of normal value).
• Patients with positive for antibodies to hepatitis B core (anti-HBc), hepatitis B surface antigen (HBsAg) or hepatitis B e antigen (HBeAg)。
• Known highly allergic constitution or allergic to the test drug.
• Subjects with diabetes, severe cardiopulmonary and pulmonary disease, and hematological diseases, malignant tumors, or systemic infection, immunocompromised patients and patients with psychosis.
• Subjects with other types of abnormal growth and development, such as Turner syndrome, constitutional delay of puberty, Laron syndrome, growth hormone receptor deficiency.
• Subjects who have received the treatment of Somatropin or took part in other clinical trial study within 3 months.
• Other conditions which in the opinion of the investigator preclude enrollment into the study.