Detection of small for gestational age babies and perinatal outcomes
following implementation of the growth assessment protocol (GAP) at a
New Zealand tertiary facility: an observational study.
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.