Interpretation
Our results compare well with the most recently published observational study on antenatal detection of SGA following implementation of GAP in an Australian hospital clinic setting. 7 Antenatal SGA detection rates increased significantly following implementation of GAP from 21% to 41% (OR=2.6, 95% CI 1.3, 4.9). Consistent with our findings, these authors also reported reduced overall neonatal unit admission after implementation of GAP. Pre-GAP, admission of SGA babies to the special care nursery was 18% compared to 12% post GAP whereas admission of SGA babies to the neonatal intensive care unit was 5% pre-GAP and 4.8% post-GAP. The effect of antenatal identification of SGA on other measures of neonatal outcome was not reported.

Conclusion

In our study, which is the first to evaluate the effect of implementation of GAP in a New Zealand District Health Board where women receive continuity of midwifery antenatal care, we found that introduction of GAP was associated with an almost five-fold increased likelihood of detection of SGA. While there was an increase in maternal intervention and preterm birth between epochs, this effect was not more pronounced in SGA pregnancies.
Amongst SGA babies who were identified during pregnancy, there was some evidence of reduced composite neonatal morbidity and reduced prolonged neonatal admission. GAP is a safe tool for increasing detection of SGA and suitable for application in an ethnically diverse population with high levels of obesity. Future studies should be powered to detect perinatal mortality and severe morbidity, and also to detect the impact of GAP on false positive diagnosis of SGA and on utilisation of ultrasound scanning.
Acknowledgements :

Disclosure of Interests

FJC is an educator for the New Zealand GAP programme. LMEMcC was the lead author on the NZMFMN SGA Guideline. No conflicts of interest were declared by other authors. Completed disclosure of interest forms are available to view online as supporting information.

Contribution to Authorship

All authors met authorship criteria. FJC, LMEMcC, JMcA-C and NG contributed to the concept and design of the study. AO’B and FJC performed searches, screening and data extraction. FJC, LMEMcC, JW and CMcK analysed the data. FJC and LMEMcC drafted the manuscript. RST formatted the tables and diagrams, and assisted in editing the manuscript. LMEMcC, JMcC-C, and NG supervised the study and contributed to interpretation of data. All authors reviewed draft versions of the manuscript and accepted the final version. LMEMcC is the senior author on this manuscript.
Transparency declaration
As the lead author, FJC affirms that this manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted.