Delaying babies defies nature, according to IVF specialists writing in the British Medical Journal. “Women want to ‘have it all,’ but biology is unchanged; deferring defies nature and risks heartbreak. If women want room for manoeuvre they are unwise to wait till their 30s,” say three London fertility experts. They speculate that “the availability of in vitro fertilisation (IVF) may lull women into infertility while they wait for a suitable partner and concentrate on their careers and achieving security and a comfortable living standard.”

The article in the BMJ lists many disadvantages of trying to become pregnant after 35, both physical and psychological. “It is ironic that as society becomes more risk-averse and pregnant women more anxious than in the past, a major preventable cause of this ill health and unhappiness is unacknowledged. Public health agencies target teenagers but ignore the epidemic of pregnancy in middle age,” they say.

Although most fertility specialists have been issuing similar warnings for years, many women resent being told that that they should try to start a family earlier in life. The medical editor of New Scientist, Clare Wilson, responded with a personal letter to the BMJ complaining about the authors’ “inflammatory language” and dismissing the suggestion that women use IVF as a safety net. Another woman commented that “many of us have had no choice but to settle for a career instead of motherhood”.