So baby Jo, most likely, wasn't a miracle after all. Elizabeth Buttle who stunned Britain by apparently conceiving a baby naturally, and having it at 60, now it seems had a little artificial help. The whole drama was more about age limits and fertility treatment than anything else. But it did put the spotlight briefly on a fascinating subject; at what age can a woman still have a baby naturally and how common is extremely late motherhood without artificial assistance?
While maternity hospitals in Dublin, Galway and Cork can readily call to mind patients in their charge who have given birth in their late 40s, very few can recall having cases - at least not in recent times - where women in their 50s experienced natural conception, pregnancy to full term and delivery of healthy babies. Having babies without fertility treatment beyond the age of 48 or 49 is considered highly unusual - a rare phenomenon indeed. And worldwide average age for the onset of menopause is 51.
"Only about 2 per cent of births are to women over the age of 40, and births to women over the age of 45 are very unusual," says Dr Michael O'Dowd, obstetrician and gynaecologist at Portiuncula Hospital, Ballinasloe, Co Galway. Quoting from national statistics, he says that perhaps contrary to public perception of "mature pregnancies being more common in rural areas" the figures are the same for Dublin as for the rest of the country. "You have to remember that professional women in urban areas are now leaving it later to have children," he adds.
While it is commonly known that women continue to be fertile until they reach the menopause, the fact that many women can still become pregnant for more than a year after they cease having regular periods may come as a surprise to many.
"The definition of the menopause is that the woman doesn't have a period for one year, but after one year, up to 4 per cent of women ovulate occasionally, which means they could produce an egg and have a period after that," says Dr Valerie Donnelly, assistant master at the National Maternity Hospital, Holles St, Dublin, and head of the menopause clinic there.
"A number of women are sent to the menopausal clinic here with abnormal bleeding once their menopause has begun, but this bleeding is often normal," says Dr Donnelly, who points to an ongoing study in Melbourne, Australia (The Women's Midlife Health Study) which has found women up to the age of 56 who were still able to become pregnant in this way.
The other category of older mothers with the ability to have a baby are those who have a late menopause. "Five per cent of women still have regular periods up to the age of 56, but it is very unusual to see women who regularly menstruate after that age," says Dr Donnelly. Given these figures, Elizabeth Buttle may have been one of those few women who had a very late menopause and who may also have continued ovulating after her menopause began.
Just as an early onset of menopause has hereditary factors, so too does the late onset of menopause. Family histories can therefore provide valuable information to women interested in understanding their fertility pre and post-menopause.
Another factor which comes into play is smoking, and women who smoke tend to begin their menopause two years earlier than the otherwise expected age of onset.
The declining quality of the female ova (eggs) is perhaps the main reason why few women give birth over the age of 45. "The quality of the eggs starts to decline from the age of 40 which means the risk of miscarriage and foetal abnormalities is increased," says Dr Donnelly.
IN general, female babies are born with approximately 300,000 eggs each (curiously, the female foetus at 20 weeks has the maximum number of eggs) and the number decreases steadily from then on. On average, women lose eggs at a rate of 1,500 per month with only a few eggs in each cycle reaching maturity and usually only one being released ready to be fertilised by a sperm.
One interesting theory which has emerged following the issues raised the Buttle case is that giving birth in your late 40s and 50s may increase your chances of living to old age. "He's my little miracle and he makes me feel like a young woman again," Buttle said when Joseph was born in November, 35 years after the birth of her only other child, a daughter born in 1962. "You could argue that having a baby late in life may improve your longevity. Children tend to keep you young, although you may feel that they wear you out," says Dr Michael Turner, master of the Coombe Women's Hospital, Dublin. Interestingly, Dr Turner concluded from a study of more than 800 mothers aged 40 or more that pregnancy in this age group did not constitute a serious risk to the mother's health. Likewise, the health of the baby was determined more by such factors as reproductive history and social circumstances than the age of the mother.
Research carried out in the obstetrics and gynaecology department at Harvard University goes a step further. Looking at women born in 1896, the study found that those who lived to be 100 were four times more likely to have had children when they were more than 40 than women born in the same year who survived only to their mid-70s.
The Harvard team also believes that extended fertility acts as a protective feature against the onset of diseases of old age like Alzheimer's.
"It sounds plausible," says Dr Donnelly when the Harvard study is cited to her. "It is well known that the presence of oestrogen has a beneficial effect on ageing as it reduces the likelihood of heart disease and osteoporosis."
Women who have a late menopause and/or those who continue ovulating after the onset of menopause will still have naturally occurring oestrogen in their bodies, and the artificial oestrogen given to women on Hormone Replacement Therapy helps prevent such problems as osteoporosis and heart disease as well as relieving the symptoms of menopause. "Being on HRT however does not alter your fertility," cautions Dr Donnelly. "If you are going to ovulate after the menopause has begun, HRT will not stop you doing so. It is definitely not a contraceptive."