Objective To investigate the efficacy of fetal biometric measurements combined with Doppler hemodynamic indices in late pregnancy for predicting the delivery of full-term small for gestational age (SGA) infants.

Methods A retrospective analysis was conducted in 80 pregnant women who delivered full-term SGA infants in the Maternal and Child Healthcare Hospital of Tongzhou District in Beijing from June 2023 to December 2024 (case group), and another 80 pregnant women who delivered full-term appropriate for gestational age (AGA) infants during the same period (within 2 weeks) were selected as control group. Fetal biometric measurements biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femoral length (FL) and Doppler hemodynamic indices pulsatility index (PI) and resistance index (RI) of the umbilical artery (UA) and fetal middle cerebral artery (MCA) in late pregnancy (28 to 32 weeks of gestation) were compared between the two groups. The predictive efficacy of these indices for full-term SGA was analyzed using receiver operating characteristic (ROC) curve.

Results There were no significant differences in maternal age, gravidity, parity, mode of delivery, gestational age at delivery, and pregnancy complications between the case and control groups (P>0.05). However, a significant difference was observed in neonatal birth weight between the two groups (P < 0.01). In the case group, fetal biometric measurements (BPD, HC, AC, and FL) in late pregnancy were significantly lower than those in the control group(P < 0.01). The PI and RI of the UA in late pregnancy in the case group were significantly higher than those in the control group, while the PI and RI of the MCA were significantly lower (P < 0.01). The area under the curve (AUC) for the combined ultrasound indices in predicting the delivery of full-term SGA infants in late pregnancy was 0.909, which was significantly higher than AUC values for individual measurement of BPD (0.749), HC (0.755), AC (0.799), FL (0.783), UA-PI (0.828), UA-RI (0.807), MCA-PI (0.810), or MCA-RI (0.799) (P < 0.05).

Conclusion Fetal biometric measurements combined with Doppler hemodynamic indices in late pregnancy can reflect fetal intrauterine growth status and provide high accuracy in predicting the occurrence of full-term SGA.