Introduction: Labour pain is one of the most severe types of pain ever to be experienced. Entonox is a nitrous oxide (N2O), a self administered patient controlled inhalational analgesia. Our research is focused to study about this aspect of Entonox that is reduction in the duration of labour by making cervical dilatation faster. The aims and objectives of our study was to determine the effect of entonox on duration of first stage of labour and to determine the effect of entonox on rate of cervical dilatation.

Methodology: A prospective observational study was carried out Pushpagiri Institute of Medical Sciences and Research Centre in Kerala, India, for a period of 6 months consecutive sampling: sample size obtained is 20 per group, grouped them into two groups depending upon the analgesic of choice. The study tool was a Performa and variables entered into Microsoft excel spreadsheet and analysed SPSS 18.0 software package. Results presented as frequency and percentages for categorical data and descriptive statistics for continuous data. The duration of labour was presented as mean and SD and cervical dilatation rate is calculated as cm in dilatation divided by duration of first stage and this also was presented as mean and SD. These two outcome variables was compared between entonox and control Mann-Whitney U Test.

Results: There was 20 study participants each in the two groups. 10 primigravidas and 10 multigravidas, with mean age was 28.15 ± 2.66 years and majority of them belong to normal BMI. Although there was no difference with respect to the cervical dilatation at the onset of usage of Entonox, it was observed that there was significant reduction in the duration of labour and usage of Entonox as there was a increase in cervical dilatation rate when compared to women who chose other analgesics. All these factors also found to be statistically significant.

Conclusion: A part from analgesic effect nitrous oxide also is shown to decrease the duration of active phase of labour by making cervical dilatation faster and lowering the duration of usage of labour analgesics, which makes labour a pleasant experience for woman.