To evaluate the diagnostic value of mid-pregnancy ultrasound combined with thyroid hormone examination for asymmetrical fetal intrauterine growth restriction (IUGR).

A total of 6010 naturally conceived single fetuses in the second trimester of gestation were selected at the Second Affiliated Hospital of Nanjing Medical University from June 2016 to June 2019, among which 97 cases of fetuses with asymmetrical IUGR were included in an observation group. Thirty cases of fetuses during normal pregnancy were included in a control group. Mann-Whitney U test and independent sample t test were used to compare the difference of maternal serum thyroid stimulating hormone (TSH) and free thyroxine (FT₄) between the observation group and the control group at (18±1) weeks and (22±1) weeks of pregnancy. The receiver operating characteristic (ROC) curve was used to analyze the value of maternal TSH and FT₄ in predicting fetal growth retardation at (18±1) weeks and (22±1) weeks of gestation.

The FT₄ levels of the observation group were significantly lower than those of the control group at (18±1) weeks and (22±1) weeks [(10.74±2.87) pmol/L vs (14.83±1.91) pmol/L, t=-6.978, P<0.001; (11.96±2.87) pmol/L vs (15.28±2.14) pmol/L, t=-6.793, P<0.001], but TSH was significantly higher in the observation group than in the control group at (22±1) weeks [2.52 (1.74~3.21) mIU/ml vs 1.96 (1.54~2.76) mIU/ml, Z=-2.191, P=0.028]. There was no significant difference in maternal TSH between the two groups at 18±1 weeks (P>0.05). At (18±1) weeks and (22±1) weeks, the sensitivities of maternal FT₄ in predicting fetal growth retardation were 96.7% and 100%, respectively, which were significantly higher than those of TSH (32.4% and 55.2%). However, maternal TSH predicted fetal growth retardation more specifically than FT₄ (90.0% vs 75.7%, 73.3% vs 56.2%).

Ultrasound combined with thyroid hormone detection has appreciated predictive value for asymmetrical IUGR in the second trimester of pregnancy.