Ultrasound Assessment of Fetal Growth Parameters

Inclusion Criteria: Singleton pregnancy; The date of the last menstrual period was determined for each pregnant woman, and a history of regular menstrual cycles was confirmed; Pregnant women had no maternal diseases that could affect fetal growth and development, such as diabetes, pregnancy-induced hypertension, or chronic infections; Fetuses had no chromosomal or structural abnormalities; Gestational age (calculated based on the last menstrual period) was within 7 days of the ultrasound biometric measurements; Good image quality. Exclusion Criteria: Multiple gestation, fetal demise, or stillbirth; Pregnancy complications or comorbidities affecting fetal growth; Clinically diagnosed fetal growth restriction (FGR); Confirmed pathogenic infections (serology-positive), including TORCH, HIV, RPR, or other infections; Prenatal ultrasound indicating fetal hydrops, structural anomalies, or chromosomal abnormalities; History of substance abuse (e.g., drugs, smoking, alcohol) or medication use in early pregnancy; Discrepancy between clinical gestational age and ultrasound-estimated gestational age; Lack of follow-up information.