Affiliations:
1 Dept of Midwifery, Auckland University of Technology, Auckland, New Zealand
2 Perinatal Institute, Birmingham, UK.
3 Liggins Institute, Faculty of Medical and Health Sciences, University of Auckland,
Auckland, New Zealand,
4 Kidz First Neonatal Care, Counties Manukau Health, Auckland, New Zealand
5 Dept of Obstetrics and Gynaecology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
6 Dept of Paediatrics: Child and Youth Health, Faculty of Medical and Health Sciences, Auckland, New Zealand
7 Dept of Biostatistics and Epidemiology, Auckland University of Technology, Auckland, New Zealand.
8 Health Intelligence and Informatics, Counties Manukau Health, Auckland, New Zealand
9 South Auckland Clinical School, Level 3, Esme Green Building, Middlemore Hospital, Auckland, New Zealand.
Corresponding Author:
Professor Lesley ME McCowan
Email: l.mccowan@auckland.ac.nz
Correspondence: Dept of Obstetrics and Gynaecology, FMHS, The University of
Auckland, Private Bag 92019, Auckland 1142, New Zealand.
Running Title: Evaluation of growth assessment protocol (GAP) – New Zealand

Abstract:

Objective: To assess the impact of implementation of GAP in a multi-ethnic population with high obesity and high deprivation.

Design/Methods: Retrospective before (2012) and after (2017) study (pre-and post-GAP). Outcomes were compared between epochs with adjustment for New Zealand Deprivation Index, maternal body mass index, ethnicity, cigarette smoking and age.

Setting: Counties Manukau tertiary maternity facility, Auckland, New Zealand

Population: Singleton, non-anomalous pregnancies, booked with a hospital midwife by 20 weeks’ gestation, with birth after 24 weeks’ gestation.

Main Outcome Measures: Antenatal detection of SGA babies (<10th customised centile), labour induction, caesarean section and composite adverse neonatal outcome (neonatal unit admission >48 hrs, 5-minute Apgar Score <7, any ventilation).

Results: Antenatal detection of SGA increased after introduction of GAP from

22.9% to 57.9% (aOR=4.81, 95% CI 2.82, 8.18) with similar SGA rates
across epochs (13.8% vs 12.9%; p=0.68). Induction of labour and caesarean birth increased between epochs, but this increase was similar in SGA and non-SGA. Amongst SGA, increased antenatal identification post-GAP appeared to be associated with lower composite adverse neonatal outcome (identified SGA: pre-GAP 32.4% vs post-GAP 17.5%, aOR=0.44, 95% CI 0.17, 1.15; non-identified SGA: pre-GAP 12.3% vs post-GAP 19.3%, aOR=1.81, 95% CI 0.73, 4.48; interaction p=0.03).

Conclusions: GAP was associated with an almost 5-fold increased likelihood for SGA detection, without significant increase in maternal intervention and some evidence of a reduction in composite adverse neonatal outcome in identified SGA pregnancies. GAP is a safe, effective tool for SGA detection in an ethnically diverse population with high obesity levels.

Tweetable Abstract: GAP is a safe and effective tool for increasing detection of SGA in an ethnically diverse population with high levels of obesity.

Key words: Small for gestational age, SGA, caesarean section, growth assessment

protocol (GAP), induction of labour, composite adverse neonatal outcome