The finding comes from a US-Italian study of 782 healthy couples who were using natural family planning methods to avoid pregnancy.
US-based lead author Dr David Dunson said that, to his knowledge, this was the first study to observe that a womans fertility started to decline before the age of 30. However, he reassured women that this did not mean a lower overall probability of achieving pregnancy if they delayed trying to become pregnant until their late 20s or early 30s, but it meant that it may take a month or two longer to become pregnant than it would have in their early 20s.
"Although we noted a decline in female fertility in the late 20s, what we found was a decrease in the probability of becoming pregnant per menstrual cycle, not in the probability of eventually achieving a pregnancy," he said.
The study found evidence that it is not only women who need to be concerned about their biological clock; mens fertility also begins to decline from as early as their late 30s.
However, there was some encouraging news for older would-be parents age did not decrease the duration of the fertile window the 6 days within the menstrual cycle when women were most likely to become pregnant.
The study, carried out by the National Institute of Environmental Health Sciences in North Carolina and the University of Padua in Italy, aimed to evaluate the effects of male and female age on natural fertility by controlling for variation in sexual behaviour. According to the authors, most analyses of age-related changes in fertility cannot separate effects due to reduced frequency of intercourse from effects directly related to ageing. But this study was designed to be able to do that by controlling for frequency and timin
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Contact: Margaret Willson
m.willson@mwcommunications.org.uk
44-1536-772181
European Society for Human Reproduction and Embryology
29-Apr-2002