EP08.14: Computerised CTG features in small for gestational age and fetal growth restriction between 32+0 and 36+6 weeks

To investigate the characteristics of computerised CTG (cCTG) in suspected late-onset fetal smallness and compare cCTG analysis in small-for-gestational age (SGA) and fetal growth restriction (FGR). Single-centre prospective cohort study including a consecutive series of singleton pregnancies with suspected FGR evaluated between 32+0 and 36+6 weeks. Cases were monitored using biometry, Doppler and cCTG as per international guidelines, and the Delphi criteria were considered to discriminate between FGR and SGA. A cross-sectional analysis of the cCTG parameters reported by the Dawes-Redman algorithm was performed, and included the evaluation of the relationship between Doppler and cCGT parameters and the paired comparison of the duration of cCTG recording, baseline fetal heart rate (FHR), episodes of high and low variability, long term variability (LTV) and short term variability (STV) between cases fulfilling and those not fulfilling the Delphi criteria. Pathological STV was defined as <3.5 msec at 32+0-33+6 weeks and <4.5 msec between 34+0 and 36+6 weeks. Overall, 105 cases and 367 cCTG recordings were included, of whom 232 (63.2%) from fetuses fulfilling the criteria for FGR. A negative correlation between umbilical artery PI and UCR and LTV (-0.169, p < 0.01 and -0.220, p < 0.01, respectively) and STV (-0.181, p < 0.01 and -0.244, p < 0.01, respectively) and a positive correlation between the same parameters and length of recording (0.191, p < 0.01 and 0.197, p < 0.01, respectively) was noted. FGR fetuses showed longer duration of the cCTG recording (27 ± 16 vs 20 ± 14 minutes, p < 0.01) and lower STV (8.3 ± 2.9 vs 9.3 ± 3.1, p< 0.001). For these two parameters significance was retained at 32+0-33+6 weeks but not at 34+0-36+6 weeks. Our study demonstrates a relationship between cCTG and fetal Doppler parameters as well as differences in terms of baseline FHR, duration of the cCTG recording and STV between SGA and FGR fetuses. Pathological cCTG is uncommon and mainly accounted by FGR cases.