Women who wait beyond the age of 35 to start a family run a dramatically increased risk of pregnancy failure, according to research reported in Saturday's British Medical Journal (BMJ).
According to a report published by AFP, Friday, the Danish study found that at the age of 35, one-fifth of all pregnancies were unsuccessful, due to miscarriage, stillbirth or ectopic pregnancy. At the age of 42, the rate of failed pregnancies was more than half, it discovered.
The risk of miscarriage at the ages of 22-24 is 8.9 percent, but rises to 74.7 percent at the age of 45 years.
The risk of an ectopic pregnancy -- a highly dangerous condition, in which a fertilised egg develops in the tube between the ovary and the uterus -- also rises with maternal age, from 1.4 percent of all pregnancies at the age of 21 to 6.9 percent at 44 or more.
"Foetal loss is high in women in their late 30s or older, irrespective of reproductive history," say the authors, from the Danish Epidemiology Science Centre in Copenhagen in an interview with AFP.
"This should be taken into consideration in pregnancy planning and counselling."
The research is based on the maternal age and reproductive history of 634,272 women between 1978 and 1992, with 1,221,546 pregnancy outcomes. On average, 13.5 percent of the pregnancies intended to be carried to term ended with the loss of the foetus.
The study underscores the biological risks behind the trend, especially in prosperous Western countries, to postpone parenthood, helped by contraception and in-vitro fertilisation.
In an adjoining editorial, two professors in public health at New York's Columbia University, Zena Stein and Mervyn Susser, say there are additional biological problems, including multiple births and congenital deformities, that arise with pregnancy in the late thirties and the forties.
But, according to AFP, they say the situation is not entirely gloomy for people who hope to become parents later in life.
They can offer a child many benefits, as they have greater experience and usually enjoy a better economic situation than many of their younger counterparts, say Susser and Stein.
"In some studies that have controlled for social factors and parity, such children do better at school than those of very young parents," they write.
"In the demanding task of raising children, older parents may be less resilient than younger ones but their experience and knowledge are almost bound to be greater, their economic situation better, and child rearing more affordable. Biological disadvantage is to a degree balanced by social advantage" -- AFP.
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