Abstract:

Aim: To evaluate fetal thymus size using the thymic-thoracic ratio (TTR) in women with a pregnancy complicated with fetal growth restriction (FGR) and to assess the relationship with adverse perinatal outcomes. Materials and Method: A total of 35 pregnant women with FGR and 42 healthy pregnant women with similar demographic characteristics were included in this prospective study. In the FGR group, cases with pathological doppler flow parameters of absent end-diastolic flow (AEDF) in an umbilical artery and cerebroplacental ratio (CPR) <1 and estimated fetal weight (EFW) <3rd percentile were also recorded. The groups were compared in terms of demographic features, clinical and sonographic characteristics and fetal TTR. In the statistical analysis of the data obtained, the Mann-Whitney U and Fisher's Exact tests were used to compare the median values of the groups and categorical variables. The association between fetal TTR and adverse perinatal outcomes was investigated using Spearman's correlation coefficient. The level of statistical significance was set at p<0.05. Results: Other than the adverse perinatal outcomes of EFW <3rd percentile, oligohydramnios, pathological doppler flow, all the other parameters were similar in both groups (p>0.05). The fetal TTR was determined to be significantly lower in the FGR group than in the control group (0.37±0.02 [0.33-0.42] and 0.40±0.02 [0.36-0.45], p<0.001, respectively). A statistically significant, negative moderate correlation was determined between fetal TTR and the EFW <3rd percentile, pathological doppler flow (AEDF and CPR<1) (r= -0.703, r= -0.588, r= -0.383, r= -0.418 and p<0.001, p<0.001, p=0.023, p=0.012, respectively). Conclusion: This is the first study to have evaluated the fetal TTR measurement in FGR-complicated pregnancies. A lower fetal TTR supports the relationship between FGR and fetal thymic involution. Moreover, fetal TTR might be a sonographic indicator for predicting adverse perinatal outcomes.

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