Environments For Healthy Living (EFHL) Griffith birth cohort study: characteristics of sample and profile of antenatal exposures

Table 1 Sample characteristics of the EFHL infant cohorts 2006–2010, compared with regional and national population data

	EFHL study sample	Study population^a	Reference population^b	P-value
Infant Characteristics	N=2908	N=45,669	N=1,441,424
Gender of infant
Males	1448 (50.5)	23,498 (51.5)	735,479 (51.4)	0.315 (Study)
Females	1420 (49.5)	22,170 (48.5)	694,495 (48.6)	0.312 (Reference)
Missing	40	1	11,450
Plurality
Singleton	2850 (98.0)	44,568 (97.6)	1,395,372 (96.8)	0.173 (Study)
Multiple	58 (2.0)	1,101 (2.4)	46,052 (3.2)	<0.001 (Reference)
Missing	0	0	0
Gestational age at birth
<28 weeks	0 (0.0)	273 (0.6)	12,881 (0.9)	<0.001 (Study)
28-36 weeks	95 (3.3)	2,912 (6.4)	105,235 (7.3)	<0.001 (Reference)
37-41 weeks	2734 (96.1)	42,227 (92.5)	1,308,933 (90.8)
>41 weeks	17 (0.6)	245 (0.5)	13,761 (1.0)
Missing	62	12	614
Live births
Live	2904 (99.9)	45,368 (99.3)	1,430,500 (99.2)	0.001 (Study)
Still born	4 (0.1)	301 (0.7)	10,815 (0.8)	<0.001 (Reference)
Missing	0	0	109
Birth weight
<2500g	76 (2.7)	2,484 (5.4)	97,524 (6.8)	<0.001 (Study)
2500-3999g	2319 (81.6)	37,287 (81.7)	1,170,968 (81.3)	<0.001 (Reference)
>4000	448 (15.7)	5,894 (12.9)	172,169 (11.9)
Missing	65	4	763

^a Study population includes all births in the Logan, Beaudesert, Gold Coast and Northern Rivers Health Districts. Data sources: Queensland Perinatal Statistics 2006–2010; New South Wales Perinatal Statistics 2006–2010.
^b Reference Population includes all births in Australia 2006–2010. Data sources: National Perinatal Statistics 2006–2010.
^c Pearsons chi-squared.

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