Impact of analysis technique on our understanding of the natural history of labour: a simulation study

OBJECTIVE

To evaluate the discrepancy between historical and more recent descriptions of the first stage of labour by testing whether the statistical techniques used recently (repeated-measures polynomial and interval-censored regression) were appropriate for detection of periods of rapid acceleration of cervical dilatation as might occur at the time of transition from a latent to an active phase of labour.

DESIGN AND SETTING

A simulation study using regression techniques.

SAMPLE

We created a simulated data set for 500 000 labours with clearly defined latent and active phases using the parameters described by Friedman. Additionally, we created a data set comprising 500 000 labours with a progressively increasing rate of cervical dilatation.

METHODS

Repeated-measures polynomial regression was used to create summary labour curves based on simulated cervical examinations. Interval-censored regression was used to create centimetre-by-centimetre estimates of rates of cervical dilatation and their 95th centiles.

MAIN OUTCOME MEASURES

Labour summary curves and rates of cervical dilatation.

RESULTS

Repeated-measures polynomial regression did not detect the rapid acceleration in cervical dilatation (i.e. acceleration phase) and overestimated lengths of labour, especially at smaller cervical dilatations. There was a two-fold overestimation in the mean rate of cervical dilatation from 4 to 6 cm. Interval-censored regression overestimated median transit times, at 4- to 5-cm cervical dilatation or when cervical examinations occurred less frequently than 0.5- to 1.5-hourly.

CONCLUSION

Repeated-measures polynomial regression and interval-censored regression should not be routinely used to define labour progress because they do not accurately reflect the underlying data.

TWEETABLE ABSTRACT

Repeated-measures polynomial and interval-censored regression techniques are not appropriate to model first stage of labour.

Carrying their own medical records: the perspective of pregnant women

Freedom of information, access to and ownership of medical records are current and controversial issues in Australia. Relating to pregnancy and birth the debate provokes emotional responses and raises important questions about access to information, decision-making, responsibility, power and control. The aim of this qualitative study was to explore the impact on pregnant women of carrying their medical records throughout pregnancy Twenty-one women participated in face-to-face individual interviews, which were coded for thematic analysis. The study found the reaction of women toward carrying their own records to be overwhelmingly positive. Maternal record holding had the potential to improve the level of communication between the health care worker and the pregnant woman and provided a greater sense of sharing and communication within the family The study also established that maternal record holding was of benefit to the woman's partner who was better informed and more involved in the pregnancy All but one of the women who participated favoured carrying their records in subsequent pregnancies. A concern about the potential for losing or misplacing records was not seen in this study, as no women lost their records. A sense of ownership would argue against this possible drawback.