Women were recruited between June 2009 and April
2011. Assessment of 8673 medical records identified
4532 eligible women (figure 1), of whom 30% (1357)
were invited to participate; on any given day only one
researcher undertook recruitment and was therefore
unable to approach all potentially eligible women.
Women were approached sequentially to avoid selection
bias. Of those approached, 74% (1003/1357) agreed to
participate. Six-month follow-up interviews were undertaken
between December 2009 and November 2011,
and a response rate of 91.1% (914/1003) was achieved.