Latest studies warn that postponing childbirth might hike the chances of a caesarean section. A delay in childbirth, the study suggests, might be linked to the increasing rates of C-sections.
Previous epidemiological studies have reported a trend of increased rates of caesarean sections with maternal age, which is consistent in different countries. However, the reason for these augmented rates remains unclear.
The new study led by Professor Gordon Smith from Cambridge University, UK was carried out in two parts.
First, the researchers analysed data collected by the Scottish Morbidity Record (SMR2) from 1980 to 2005, where the team found linear association between the risk of having a caesarean section and advancing maternal age in first pregnancies
They observed striking changes over the period of study. The proportion of women aged 30-34 increased three fold, the proportion aged 35-39 increased seven-fold and the proportion aged 40 or older increased 10-fold.
Over the same period, the caesarean rate more than doubled. The researchers estimated that around 38 pct of the additional procedures would have been avoided if maternal age distribution had remained the same as in 1980.
They therefore concluded that a substantial proportion of the increase in caesarean section rates might be due to the trend of delaying first childbirth.
In the second part of the study, the team hypothesized that the increased risk of caesarean section among older women is a result of a biological effect of aging on the ability of the muscle of the uterus to contract.
They evaluated this hypothesis by examining biopsies from the uteruses of a separate group of 62 women (of mixed parity) undergoing routine elective caesarean delivery in Cambridge.
They found that advancing age was associated with impaired uterine function as evidenced by a reduced degree of spontaneous contraction and the type of spontaneous contraction.
The researchers' further work at the NIHR Cambridge Biomedical Research Centre at the Rosie Hospital in Cambridge, UK suggests a possible mechanism for the association of maternal age and caesarean section rates, impaired contraction of the uterus.
The authors comment, "understanding the determinants and management of dysfunctional labour in older women is central to designing strategies for reducing population caesarean delivery rates without adversely affecting maternal and infant outcomes."