Introduction

In developed countries, there has been an undeniable trend towards later childbearing. In 1968, the average maternal age at first birth in the UK was 23 years. In 2007, data from the Office for National Statistics revealed that the average age was between 30 and 31 years. In 1985, 7.9% of births in England and Wales were in women aged 35 years or over but by 1995 this statistic had increased to 11.8%. This dramatic shift towards voluntary postponement of motherhood beyond the age of 30 years reflects the changing role of women in society. Historical changes such as the introduction of the contraceptive pill in the early 1960s, subsequent abortion legislation and the advent of amniocentesis and improved antenatal and obstetric care have allowed this societal move to occur. Increasing economic opportunities for women and rising divorce rates have led to the concept of the ‘working mother’ becoming increasingly the norm. The development of assisted reproductive technologies (ART) has resulted in the traditional perceptions of childbearing capability being changed, with, for example, a woman in Romania giving birth at the age of 66 years.

In contrast with this, studies show that the biomarker age of fertility is 38 years, with a 2—3 times increased risk of permanent childlessness in women aged 38 years or over compared with those under 30 years. Defining ‘the older mother’ is problematic as studies use varying cut-off points. More recent studies use 38 years as the biomarker age.