The National Women's Health Study: assembly and description of a population-based reproductive cohort

BMC Public Health

Table 1 The National Women's Health Survey – response rates

STAGE 1	No.	Crude %	Adjusted¹ %
TOTAL QUESTIONNAIRES POSTED	60,814	100%	-
Returned undelivered²	3,661	6%	-
Responded	26,050	43%	46%
Did not wish to participate	2,738	5%	5%
Aged >55 years or otherwise ineligible³	5,564	9%	10%
Aged < = 55 years but never attempted to have children	4,713	8%	8%
Aged < = 55, ever attempted to have children	13,035	21%	23%
Among whom,
- Never pregnant	340	3%	-
- Ever pregnant	12,695	97%	-
STAGE 2
TOTAL QUESTIONNAIRES POSTED	10,828	100%	-
Returned undelivered	16	0.2%	-
Responded	7,882	73%	73%
No longer wished to participate	180	2%	2%
Completed questionnaire	7,702	71%	71%
Among whom,
- Attempted pregnancy, never pregnant	194	3%
- Ever pregnant ⁴	7,508	97%

¹ Adjusted for undelivered mail ² Includes 70 women who died before the study start ³ Under 18 at study start (6^th November 2001); male; foreign national; or too ill to participate ⁴ 344 women who had had a miscarriage since 1995, but whose last pregnancy was not a miscarriage, were sent a second stage 2 questionnaire and were asked to supply details in relation to their most recent miscarriage. 285 (83%) of the women responded to this third questionnaire.

ISSN: 1471-2458