The effect of an enhanced fetal growth ultrasound protocol on pregnancy outcomes: A retrospective service evaluation within a single UK National Health Service centre between 2014 and 2022.

Aim: Growth Assessment Protocol is a fetal growth initiative designed to improve antenatal detection of babies who are small-for-gestational-age and reduce stillbirths. However, its direct impact on pregnancy outcome and stillbirth rates is questioned. This service evaluation aimed to assess Growth Assessment Protocol's influence on pregnancy outcomes at a National Health Service hospital.

Method: Anonymous, maternity and ultrasound data, routinely acquired between 2014 and 2022 were extracted from clinical databases (Viewpoint, Euroking). Trends in maternity data and ultrasound scan volume were explored with descriptive statistics. Variables of stillbirth, antenatal small-for-gestational-age detection and scan volume were compared before and after Growth Assessment Protocol implementation. Associations between these variables were evaluated using Spearman's rho.

Results: The percentage of babies born small-for-gestational-age reduced by 0.3% across the evaluation period. Antenatal small-for-gestational-age diagnosis rose from 4.1% to 14.3%. However, the number of false-positive cases of antenatally diagnosed small-for-gestational-age increased fivefold from 2.2% to 11.5%. Although stillbirth rates remained consistent post-Growth Assessment Protocol, complex scan volume (e.g. number of growth scans using Doppler) increased annually. The peak incline coincided with the Growth Assessment Protocol implementation period (2016-2018). Complex scan volume was significantly associated with overall small-for-gestational-age detection (rho = 0.8, p =< 0.001), but not with stillbirth frequency (rho = -0.1, p = 0.4).

Conclusion: Small-for-gestational-age detection increased following Growth Assessment Protocol implementation, although this was associated with a high false-positive rate and no reduction in stillbirths. The potential implications associated with clinical management, parent experiences and departmental workflow, alongside the benefits for stillbirth reduction, should be fully considered prior to the introduction of a new fetal growth initiative to the antenatal care pathway.