698: Detected vs undetected small-for-gestational-age: a multicenter retrospective study at tertiary centers

An evaluation of the potential to improve perinatal outcomes by improving antenatal detection of small for gestational age babies in Scotland: a retrospective population cohort study

Background: Small for gestational age (SGA) babies are at high risk of perinatal mortality. We aimed to determine the potential to reduce perinatal mortality by improving antenatal detection of SGA babies in Scotland. Methods: We conducted a retrospective population study of all singleton SGA babies born in the 15 Consultant-led maternity units in Scotland in a 3-month period (1st Dec 2014 to 28th Feb 2015 inclusive).  Demographic and pregnancy outcome data were extracted from Scottish birth records for all pregnancies; case note review was performed for all SGA cases [defined as birthweight less than the 10th centile for their gestational age at delivery as defined by the appropriate sex-specific UK-WHO Child Growth Standards]. Results: The SGA rate in Scotland was 5.5% (673/12218; 95% confidence interval [CI] 5.1, 5.9) and 27.6% (186/673; 95% CI 24.3, 31.2) of SGA cases were identified prior to delivery. SGA was associated with 18.2% (12/66; 95% CI [10.1%, 30.0%) of all perinatal deaths. The majority (10/12, 83.3%) of SGA babies who died had been identified as SGA in the antenatal period. There was no difference in perinatal mortality whether SGA was detected or not (5.4% [10/186; 95% CI 2.8, 10.0] in the SGA detected group vs 0.4% [2/487 [95% CI 0.3, 2.2] in the non-detected group after adjusting for risk factors for SGA, gestation at delivery and birthweight centile (Adjusted odds ratio [AOR] 0.85 [95% CI 0.5, 1.5], p=0.556). Conclusions: Despite only around a quarter of SGA babies being identified antenatally, the potential to reduce perinatal mortality in the Scottish population by improving SGA detection is limited. Only a minority of perinatal deaths occurred in SGA babies; and in the majority of these SGA was detected antenatally.