‘Staying the distance’: characteristics of women who do not continue in a longitudinal study of pregnancy-related moods

Abstract

Many studies suffer from threats to the study design that arise through random and non-random loss of respondents and the effects on the data that is able to be collected. In quasi-experimental research, participant response problems relate particularly to the three categories of refusal to enter the study although eligible, eventual non-response in spite of previous agreement to participate, and, in longitudinal designs with repeated measures, attrition or ‘drop-out’ occurring during later stages. The results hat are eventually reported are limited to the findings from only those who remained, from whom the data were actually obtained. In the many studies carried out to identify pregnancy-related dysphoria, a key question from such studies is how truly accurate these reports really are. A large study of 642 pregnant women recruited during weeks 12 – 16 at antenatal booking-in clinics was designed in two stages where, in Phase I all were required to take part in a structured interview on a comprehensive range of issues carried out by trained antenatal midwives. Only 65% (n = 422) of the pregnant women agreed to continue on to complete the Phase II longitudinal evaluation that proceeded to the sixth postnatal week. Comparisons were made between the characteristics of those women who continued, the stayers, with the others, the withdrawers, who did not participate beyond Phase I. Significant differences were found between the two groups on demographic details of age, education and occupation, prior and current mental health status, current health risk behaviours and experiences of relationship abuse. The women who withdrew were younger, in less established relationships, under-employed, with lower education, and significantly more likely to have prior or current histories of psychiatric illness. The findings underscored the point that the withdrawers are the more needy and troubled women and the most deserving of professional attention and assistance. Attention is drawn to the need to engage with all pregnant women at an early stage in order to identify those most likely to require additional support, especially from mental health services. These women are the ones who frequently disappear from research studies and whose difficulties remain unidentified and unaddressed.