This article examines the question as to what is the right age to reproduce from the biological point of view of its purpose; that of achieving a healthy mother and baby. We start with an assumption that issues surrounding sex, fertility, pregnancy, miscarriage, abortion and childbearing are private and emotionally laden. We are not looking at, nor judging, individual reproductive choices; what might be “right” for one person, or couple, in one context will be unsuitable for another. It is traditional obstetric and gynaecological teaching that human reproductive outcomes are worse at the extremes of maternal age. Yet the advice given in a recent BMJ editorial entitled “Which career first? The securest age for childbearing remains 20–35” appeared to be controversial. The ensuing scientific and media interest raised such headlines as “Horns of the dilemma”, “A sinister article”, “Late mums face baby misery” and “Are we having children too late? IVF not the answer, say docs”. Products have recently appeared on the market offering kits to women to indicate the time left on their ‘biological clock’ so they can choose whether to continue pursuing their career or try for a baby. Why is there so much interest in the right time to reproduce? Are women (and men) doing something differently compared to the past? If there has been a demographic shift in the age women reproduce (hitherto unexplained), there are important and specific risks older women may face as compared to younger women.