This is the first study to show that an intervention delivered to women in the immediate and early post partum reduces the likelihood of urinary incontinence three months later. The finding that women in the intervention group were significantly more likely to be performing pelvic floor exercises at adequate levels during the three month period after giving birth strengthens the causal role of the intervention.
Firstly, the results of the main effects of the intervention are of marginal statistical significance, with comparatively wide confidence intervals. When residual confounding was controlled for in the logistic regression, however, the strength of the association increased slightly. We analysed by intention to treat. It is possible that the effect would be strongest among women who participated in all components of the intervention. Secondly, we need to consider the external validity of the study, as the sample was drawn from only three hospitals. But these hospitals—urban public, urban private, and rural—served diverse population groups. Thirdly, the response rate indicated that only just over half of women who might have participated in the study actually did so. The fact that women were missed is a reflection of current practice in many maternity hospitals in Australia. Women are encouraged to leave hospital within hours of delivery, with home support provided by visiting midwives; women with private health insurance usually choose to convalesce in private hospitals.
We did not approach women who had had a stillbirth or a baby in neonatal intensive care, women who had a disability that meant that they could not perform pelvic floor exercises, women who were not residents of Australia, and women who could not speak English sufficiently to give consent. As 79% of the women approached agreed to enter the study, however, bias due to non-consent was minimised.
Women were not blinded to whether they were in the intervention or the control group. They were, however, explicitly told that the study was not measuring their personal individual exercise practice in any punitive fashion but rather whether the intervention helped them to remember to do their pelvic floor exercises. In spite of this, women might have felt socially pressured to admit to exercise levels above those that they performed. Another consideration is that levels of pelvic floor exercise were measured by using self report, which could lead to social desirability bias in the intervention group. There are, however, few, if any, alternatives for monitoring the performance of this type of exercise accurately.
The study also had several strengths. Firstly, we used a randomised controlled design. Secondly, the sample size was sufficient to detect a difference of around 8% between groups as significant. Thirdly, the data were analysed by intention to treat. Randomised controlled trials are highly idealised and do not mirror real clinical practice. As this study set out to examine how effectively the exercise programme was adhered to, the lack of adherence to exercise by the women in this study gives a realistic outcome that mirrors the potential for the performance of pelvic floor exercises among women who have recently given birth.
The findings have several important implications. Firstly, many women experienced incontinence after delivery. The data from the usual care group show a prevalence of urinary incontinence of 38.4% among women who had forceps or ventouse deliveries or whose babies had a birth weight of 4000 g or more. Secondly, the intervention seemed to have most effect on women with severe mixed incontinence. Although it is difficult to offer a reason for this outcome, it is important to note that urinary incontinence was based on the symptoms experienced by the women in this study and no urodynamic assessments were carried out. These results could, however, be the effect of the information regarding good bladder habits that was given to women in the intervention group.
Thirdly, it is likely that the intervention was successful because it was based on established theories of behaviour change, incorporated known principles of anatomy and physiology, and included input from consumers in its development. Since dropout rates have been shown to be high among postpartum women performing pelvic floor exercises, the use of behavioural principles seems to have encouraged adherence to the exercise programme and the performance of such exercises. That the programme was designed to exercise specific muscles and fit in with the normal daily routine of the women may have added to its acceptability. The effect of these components in women who have given birth needs to be studied in the longer term, and follow up assessment is planned at 12 months post partum.
If this programme was disseminated among and taught to women by physiotherapists, this could result in the promotion of continence in the wider population. Although the intervention in this study was delivered by physiotherapists, who used their considerable specialist expertise in prescribing exercise programmes, other health professionals such as midwives and primary care physicians could be trained to carry out the different parts of the intervention—midwives immediately after the delivery and physicians or midwives at a postpartum visit.