Overview

This study will take place at multiple sites and is divided into three phases:an initial 4-week getting-to-know-you phase,a 26-week main phase where participants receive medication,and a 4-week follow-up phase.Participants will be divided into three groups:two will receive different doses of PEG-rhGH Injection,and the third will receive hGH Injection.The goal is to determine which medication works best.

Eligibility

Inclusion Criteria:

• Born full-term and "small-for-dates" - Born at 37-41 weeks (full-term). - Birth weight below the 10th percentile for that week of pregnancy and sex .
• At least 3 years old on the day the parent signs the consent form.
• Still prepubertal (Tanner stage I - no signs of puberty yet).
• Height at the first study visit is more than 2 standard deviations below the average for his or her age and sex.
• Bone age on X-ray is no more than 1 year ahead of real age.
• Never taken growth hormone, IGF-1, or any ghrelin-like medicine before.
• Child and parent/guardian are willing to sign the consent form and follow the study visits.

Exclusion Criteria:

• Severe allergy to growth hormone or its ingredients.
• Growth-hormone deficiency.
• Any chromosome/genetic/syndrome cause of short stature.
• Other diseases that can impair growth.
• Cognitive, developmental, or psychiatric disorders that could affect assessments .
• Current or past cancer, or high familial cancer risk.
• Positive hepatitis B, hepatitis C, HIV, or active tuberculosis at screening.
• Abnormal liver or kidney blood tests.
• Pre-diabetes or diabetes at screening .
• Systemic steroids \> 28 consecutive days or \> 14 days total in the last 3 months.
• High-dose inhaled steroids \> 28 days in the last year.
• Prior use of aromatase inhibitors, GnRH analogues, sex hormones, anabolic agents, or other drugs that affect growth. 13. Unable to receive subcutaneous injections.
• Claustrophobia or inability to undergo brain MRI.
• Participated in another clinical trial with investigational treatment within 3 months.
• Any other condition that, in the investigator's opinion, makes the child unsuitable for the study.