What is the best age for a woman to give birth? According to sociologists the answer is 34.
While her biological clock may be ticking, a mother of that age will enjoy far better long-term health than a woman who gives birth at 18.
The news will come as a relief to those who decided to concentrate on their career before having a family.
Friends actress Lisa Kudrow and singer Cerys Matthews both embarked on motherhood for the first time at 34.
And at 70, Sophia Loren - who had her first son when she was 34 - receives as much praise for her health and beauty as she did as a young screen siren.
According to research in the US the health benefits of delaying motherhood increase year by year, with the best years for women to start bearing children being between the ages of 27 and 34.
Women who wait actually enjoy better health, live longer and end up having healthier babies.
Academics looked at the link between the health problems of around 3,000 women and their age when giving birth for the first time.
Women who first gave birth at an early age developed more health problems, while women who delayed birth until 34 had fewer problems.
Health benefits first started at 22 and continued to rise until 34. But problems began to increase again at 35.
"A woman who had her first child at 34 is likely to be, in health terms, 14 years younger than a woman who gave birth at 18," said Professor John Mirowsky, who led the research for the National Institute of Ageing and the National Institute of Mental Health.
While women aged 20 or 21 are more fertile and biologically fit, older mothers tend to be more mature and engage in less risky behaviour, and are more settled educationally, financially and emotionally, he said.
"Problems drop steadily the longer that first birth was delayed, up to about 34, then rise increasingly and steeply, particularly after the age of about 40," he said.
The professor told the Journal of Health and Social Behaviour: "Studies suggest that early motherhood interferes with educational attainment and predisposes women to single-parenthood, unemployment and poverty.