Comparison of Labour Progression between Nulliparous Pregnant Women of Advanced Maternal Age and Young Nulliparous Women with Spontaneous Vaginal Delivery: A Retrospective Study in a Regional Core Hospital

Background: The number of nulliparous pregnant women of advanced maternal age, defined as 35 years or older, has increased in Japan, but there has not been a study comparing labour progression between pregnant women of advanced maternal age and young pregnant women. Therefore, we aimed to evaluate roughly whether labour progression times differed according to maternal age, with cervical dilation and foetal station used as the endpoints.Methods: We retrospectively reviewed the medical records of 1573 nulliparous women who had spontaneous vaginal delivery (929 patients), were administered an intravenous uterotonic agent (372 patients) or underwent emergency caesarean section (272 patients) at Kinan Hospital. We collected data on the patient characteristics and reviewed vaginal examination data for comparisons of labour progression. The endpoints were cervical dilation of 10 cm (full dilation) and foetal station of 2 cm, as these metrics are sufficient for vacuum-assisted vaginal delivery (sufficient descent). Data on the elapsed time between the recorded time of each stage of labour and the endpoint were obtained from two groups, namely, pregnant women of advanced maternal age and young pregnant women, and compared.Results: The percentages of women of advanced maternal age were higher among those who underwent emergency caesarean section and intravenous uterotonic agent administration. When the characteristics of the pregnant women of advanced maternal age were compared to those of the young pregnant women among the 929 patients with spontaneous vaginal delivery, differences in "blood loss amount" and "vacuum delivery status" were detected. However, regarding labour progression, there was almost no difference in any of the stages when the elapsed times between each stage and full dilation or sufficient descent were compared.Conclusions: We did not detect a clear impact of maternal age on labour progression in the groups of nulliparous women who had spontaneous vaginal delivery after women who underwent emergency caesarean section or intravenous uterotonic agent administration were excluded; however, further studies with larger sample sizes of women of advanced maternal age may be needed.