(899) Assessing Antenatal and Postnatal Growth in Severe and Non-Severe Fetal Growth Restriction

Objective: Our aim was to determine if severity of fetal growth restriction (FGR) is related to growth trajectory after birth, and whether an in-utero marker of body composition, including thigh volume, correlates with growth after birth.

Study Design: In this retrospective observational study, FGR pregnancies were included, and subdivided as severe or non-severe (severe FGR indicating estimated fetal weight, EFW or abdominal circumference, AC less than 3^rd percentile, with or without Doppler abnormalities). Measures of EFW, AC, total thigh volume (TTV), lean mass volume (LMV) were extracted from antenatal scans. Fat mass volume (FMV) was calculated by subtracting TTV from LMV. Postnatally, weight (and z-scores) was measured at birth, 1-3 months, 6 months, 1-year, 3 years, and 5 years of age. Median values (and interquartile range) of indices were compared between both groups. Using Pearson correlation analysis, correlation coefficients (r) were calculated between antenatal and postnatal parameters.

Results: The cohort includes 42 severe and 14 non-severe FGR pregnancies. In the severe FGR group, median values of TTV, LMV, FMV, EFW, EFW percentile, and AC percentile were lower compared to those in non-severe group (p < 0.05); ultrasounds done at the median gestational age of 35.93 weeks in both groups. Incidence of 'accelerated growth' (increase in weight z-score greater than 0.8) was higher in severe FGR group (80.9% versus 35.7%, p 0.01), typically observed between 6 months-3 years of age (Figure 1(a), 1(b)). By 5 years of age, weight (and z-score) of infants from severe group was lower than non-severe group (p 0.04). Birthweight (BW) correlated well with TTV (r 0.62, p < 0.01), and EFW percentile (r 0.69, p < 0.01). However, no significant correlations were observed during subsequent follow-ups.

Conclusion: In severe FGR group, despite accelerated growth of infants between 6 months-3 years, the median weight is lesser compared to non-severe group at 5 years of age, which could result in false reassurance in earlier years. In-utero markers, TTV and EFW, correlate significantly and similarly with BW.