The Royal College of Obstetricians and Gynaecologists (RCOG) has issued its clearest advice yet to would-be mothers urging them to begin, and try to complete their families between the ages of 20 and 35 during their 'most fertile' years in order to avoid 'regrets'.

There has been a sharp increase in the number of women who delay having children until their late 30s and 40s, when it is acknowledged that the health risks to mother and child are far greater. Infertility, miscarriage and health problems during pregnancy are all more likely after 35.

RCOG's statement was prompted by concern for the numbers of 'older' women 'confronting the heartbreak of infertility and miscarriage' said spokeswoman Melanie Davies, a consultant at University College Hospital in London. The recommendations also include greater education on the optimum age for childbearing, in order to prevent the 'regret' of delaying plans for motherhood.

Other Royal Colleges have echoed the need to educate women of the greater risks faced by having children beyond this 15 year window. However, Louise Silverton of the Royal College of Midwives (RCM) has emphasised that despite risks, a woman's decision to have a child should be supported whenever she chooses to embark on pregnancy. 'The key issue is that they should receive sound information about the risks of giving birth later in life'.

An NHS report on the RCOG recommendations describe the risks concerned as including not only the psychological anguish associated with difficulty in conceiving a child, but also of complications during pregnancy and birth, higher blood pressure, increased risk of having a baby with a congenital abnormality, and an increased risk of pre-eclampsia, a potentially fatal pregnancy complication.

Statements from the National Childbirth Trust (NCT) and Infertility Network UK (Inuk) have both touched on reasons that women do choose to have children later in life, for example the desire to 'build a career or to achieve financial independence' before starting a family. Mary Newburn of the NCT suggests that earlier career breaks should be made possible for younger women, whilst Susan Seenan of Inuk warned that women need to realize using fertility treatment is no guarantee of success; techniques such as IVF stimulate the release of more eggs but do not compensate for the effects of ageing on egg quality.

Very little can currently be done to reverse the effects of reproductive ageing at present, and further research into IVF methods and other assisted reproduction technologies has been recommended as part of the RCOG's warnings.