Motherhood: Is later really better than never?

Celebrity mums who give birth in their 40s still tend to hit the headlines, even though more and more women are choosing to wait until after the age of 35 before they get pregnant.

Indeed, while the term "older mother" once referred to women who conceived around the age of 30, today our birthing timeline has moved significantly, with the number of older women becoming first-time mothers on the rise.

"There is no question that the age where getting pregnant is considered a possibility is definitely expanding -- we are continuing to push the time line up and up and have been doing so since the 1980s," says fertility specialist Dr Frederick Licciardi.

Over the past decade, the number of live births to mothers aged 40 and over has nearly doubled from 14,252 in 1999 to 26,976 in 2009, according to official data for England and Wales. While fertility rates for women under 35 fell in 2009, they rose among 35 to 39 year olds by 1.2%, and among 40 to 44 year olds by 2.4%. In 2008, 20% of babies were born to mothers aged 35 or over.

Just because we can push the birthing envelope, should we? Are we tinkering with Mother Nature in a way that may come back to haunt us -- if not as a society, then on an individual case-by-case, mother-by-mother basis?

"It's not an issue that is going unnoticed, that's for sure -- but right now we don't have enough medical data to tell us one way or the other if older motherhood is a good thing; there just aren't enough women over 50 who have pushed the envelope to give us a clear picture of what happens when you do," says obstetrician/gynaecologist Dr Michael Brodman.

Health, age, and pregnancy: What we do know

Among the major arguments in favour of advanced-age motherhood is that women are living longer and are essentially healthier than ever before. Brodman notes that better nutrition, better health care, more information about disease prevention, and better living conditions have all worked to increase a woman's life expectancy significantly.

At the same time, however, these benefits rarely extend to the crux of a woman's fertility -- her ovaries and her eggs.

"Despite the fact that we have advanced our longevity, menopause still remains pretty constant -- as does the fact that, as a woman ages, she produces fewer eggs, and fewer healthy eggs," says Dr Margareta Pisarska, a specialist in reproductive medicine.

That, say experts, not only means that getting pregnant gets more difficult with each birthday, if you do manage to conceive, the risk of potential problems can be significant.

Noting that, biologically, the optimal period for childbearing is between 20-35 years of age, the Royal College of Obstetricians and Gynaecologists encourages women to consider having families during this period of optimum fertility.