Table 4.

Association between perinatal outcomes of estimated fetal weight less than the 10th percentile and abdominal circumference growth velocity

	Any neonatal morbidity (n=275)		Metabolic acidosis (n=42)		5 min Apgar <7 (n=36)		Neonatal unit admission (n=229)		SGA plus any neonatal morbidity (n=49)		Severe adverse perinatal outcome (n=33)		SGA plus severe adverse perinatal outcome (n=5)
	RR (95% CI)	p value	RR (95% CI)	p value	RR (95% CI)	p value	RR (95% CI)	p value	RR (95% CI)	p value	RR (95% CI)	p value	RR (95% CI)	p value
EFW <10th (population)	1·6 (1·2–2·1)	0·001	1·4 (0·7–3·1)	0·37	2·3 (1.1–4·8)	0·03	1·6 (1·2–2·1)	0·006	10·5 (5·9–18·6)	<0·0001	1·4 (0·6–3·3)	0·45	24·3 (2·7–217·1)	0·002
EFW <10th (customised*)	1·7 (1·3–2·3)	0·001	1·5 (0·6–3·4)	0·44	1·7 (0·7–4.2)	0·26	1·6 (1·2–2·3)	0·01	9·8 (5·7–17·1)	<0·0001	1·9 (0·8–4·7)	0·14	34·8 (3·9–310·4)	0·0005
EFW <10th plus normal ACGV	1·3 (0·9–1·8)	0·23	0·3 (0·0–1·9)	0·25	1·4 (0.5–3·9)	0·54	1·4 (0·9–2·0)	0·13	7·3 (3·7–14·4)	<0·0001	0·7 (0·2–2·7)	0·76	17·6 (1·6–193·5)	0·03
EFW <10th plus lowest decile ACGV	2·5 (1·7–3·6)	<0·0001	4·1 (1·8–9·1)	0·003	4·6 (1·9–11·0)	0·004	2·1 (1·3–3·2)	0·003	17·6 (9·2–34·0)	<0·0001	2·9 (1·0–8·3)	0·06	39·8 (3·6–436·6)	0·007

All estimated fetal weights (EFWs) are based on population-based percentiles, unless stated otherwise. All relative risks (RRs) are referent to infants with an EFW of ≥10th percentile by population-based standards, except for the RRs for customised EFW <10th percentile, which are referent to infants with an EFW of the ≥10th percentile by customised standards. Appendix has n/N for every cell. Small for gestational age (SGA) is defined as birthweight of <10th percentile by population standards. Abdominal circumference growth velocity (ACGV) is based on the change in the gestational age adjusted Z score, comparing the result at the 20 week scan with the last scan before birth. Neonatal morbidity is a composite outcome—ie, one or more of these three outcomes: metabolic acidosis (defined as pH <7·1 and base deficit >10 mmol/L), 5 min Apgar score less than 7, and neonatal unit admission (defined as admission to the neonatal intensive care unit, the high dependency unit, or the special care baby unit). Severe adverse perinatal outcome is a composite outcome—ie, one or more of the following outcomes specified: stillbirth (not due to congenital anomaly), neonatal death at term (not due to congenital anomaly), hypoxic ischaemic encephalopathy at term, use of inotropes at term, mechanical ventilation at term, severe metabolic acidosis at term (defined as pH <7·0 and base deficit >12 mmol/L). p values (all two sided) are from Fisher's exact test.

^*Customised percentiles of EFW were calculated with the Gestation-Related Optimal Weight Customised Weight Centile Calculator (version 6.7 [UK]).