In the case of pregnancy, increased maternal age is a major risk factor.
Firstly, fertility declines rapidly with age. IVF has a "take-home baby" rate of 3 per cent at age 42 in most units. The rate of most pregnancy problems, medical, obstetric and foetal, rises from the late 20s, and dramatically from 35 on. Although any woman may miscarry, it is well known the rate is age dependent, being about 14 per cent at age 27, rising to 40 per cent at 40, and more than 60 per cent at 45. A similar rise with age is seen in the risk of birth defects and chromosomal abnormalities, of diabetes and high blood pressure in pregnancy, of caesarean delivery and its complications, of premature birth, of handicapped infants, and of medical problems such as thrombosis, heart, kidney and thyroid problems and cancers.
Considering all these and other medical problems, and obstetric problems dealt with by obstetricians and midwives, such as haemorrhage, of 100 women aged 28 who conceive today, no more than 70 will experience an uncomplicated pregnancy, delivery and postnatal period. At age 42, for example, only about 27 will.
My responsibility is to interpret the body of knowledge for my patients and others. In many cases involving older women with medical problems, particularly when they already have children, I have advised against pregnancy. In too many of these, I have suffered with the parents as they cuddle a lifeless bundle in a hospital room that would usually be filled with joy.
Too often I have seen maternal mortality or life-threatening illness, both catastrophes, particularly when existing children are left motherless and would not have been so had the couple left the family as it was.
Of 100 women aged 28 who conceive today, no more than 70 will experience an uncomplicated pregnancy, delivery and postnatal period. At age 42, for example, only about 27 will.
It is a public health matter. The better prognosis with earlier pregnancy should be explained to couples, together with other medical information important in planning pregnancy, to help them decide their timing.
Dr Barry Walters is clinical associate professor of obstetric medicine at King Edward Memorial Hospital for Women and Royal Perth Hospital. This is an extract from an article at the National Times.