Table 1. Demographic characteristics of the study sample (n=3,795) and the general adult population in Ireland (n=3,439,565), 2014–2016.

Characteristic		Study sample		General adult population in Ireland (>  = 18 years)a
		n	%	n	%
Sex	Female	1,931	51%	1,754,648	51%
	Male	1,864	49%	1,684,917	49%
Age group	18–29 years	856	23%	772,275	22%
	30–39 years	838	22%	758,206	22%
	40–49 years	705	19%	635,997	18%
	50–59 years	574	15%	518,908	15%
	60–69 years	436	11%	392,424	11%
	70 + years	386	10%	361,755	11%
HSE area	East	2,288	60%	1,236,870	36%
	Midlands and North East	535	14%	522,465	15%
	South and South East	556	15%	869,316	25%
	West, North West and Mid West	416	11%	810,914	24%
Category	Antenatal	646	17%	NA	NA
	Pre-employment	131	3%	NA	NA
	Other (e.g. diagnostic specimens)	3,018	80%	NA	NA
Total		3,795	100%	3,439,565	100%

^a Census 2011, Central Statistics Office, Ireland

HSE: Health Service Executive; NA: not available.