Determination of Fetal Transcerebellar Diameter Nomogram in the Second Trimester

The aim of the study was obtain nomogram of fetal transcerebellar diameter at 18-24 weeks of gestation with known prognosis of normal pregnancies. The study included 1236 healthy fetuses in the 18th-24th gestational week of women aged from 18 to 40 years (mean: 28.70 +/- 5.26). The transcerebellar diameter, bi-parietal diameter, femur length and abdominal circumference of the fetuses were measured. Additionally, groups were divided according to maternal age and according to body mass index. The transcerebellar diameter of fetuses from 18 to 24 weeks gestation varied from 18.13 +/- 2.16 to 26.42 +/- 1.91 mm (mean: 22.12 +/- 2.57 mm). Additionally, the mean and standard deviation of transcerebellar diameter and fetal parameters were determined according to gestational week, maternal age and maternal body mass index. Later, the correlations between transcerebellar diameter with pregnancy week, maternal age, maternal body mass index and fetal parameters were examined. Transcerebellar diameter was correlated with pregnancy week and fetal parameters (p < 0.01) but was not correlated with maternal age (p > 0.01). Additionally, transcerebellar diameter and fetal parameters were determined to show negative correlation with maternal body mass index (p < 0.01). Comparison of transcerebellar diameter with pregnancy week determined differences between weeks (p < 0.05), but no differences for age groups and body mass index groups (p > 0.05). Maternal age and maternal body mass index are significant factors affecting fetal development. We believe our data related to the transcerebellar diameter obtained at the end of the study will be beneficial for assessment of fetal development and identification of fetal anomalies.