Growth charts customised for maternal height, weight, ethnicity and parity have been proposed as more effective at detecting infants who are small for gestational age (SGA) than routine screening with symphysio‐fundal height measurement alone. Our non‐randomised, prospective cohort study assessed antenatal SGA detection rates in a general maternity cohort following the introduction of the Perinatal Institute’s Growth Assessment Protocol (GAP) program (consisting of customised growth chart software for plotting symphysio‐fundal height, staff training and serial auditing).

The GAP program was implemented into the routine antenatal schedule of 882 women who delivered at The Royal Women’s Hospital, Melbourne, during our study period. SGA detection was compared to 936 women from the same team who delivered prior to the intervention. Secondary outcomes assessed were infant gestation at birth and method of delivery, neonatal Apgar scores and admission to the Neonatal Intensive and Special Care nursery (NISC).

Identification of SGA infants increased from 21% to 41% with the introduction of the GAP program (OR 2.6, 95% CI 1.3–4.9, P < 0.05). This was not associated with an increase in false‐positive rates. Following the introduction of the GAP Program, SGA babies were more likely to be born by vaginal delivery (OR 2.7; 95% CI 1.4–5.1, P < 0.005). There was no overall increase in the induction of labour or caesarean delivery rates. Overall rates of admission to NISC were reduced. Conclusions In our increasingly culturally heterogenous society, the use of the GAP program is a safe and potentially more sensitive tool for detecting in utero growth restriction.