Mode of conception of twin pregnancies: Willingness to reply to survey items and comparison of survey data to hospital records.

Based on results from a survey study in a sample of Australian parents of twins, Raj and Morley (2007) reported that questions concerning the mode of conception of twins may be offensive to parents. We looked at the willingness to reply to questions about mode of conception of twin pregnancies in a large survey study that was completed by 20, 150 mothers of twins from the Netherlands Twin Registry. Data collection took place in 2005/2006. The amount of missing data was examined and by using data from earlier survey studies, responders and nonresponders were compared with respect to their answe... Mehr ...