Monday 23 February 2015 9:16am
More than a quarter of women and a fifth of men experience fertility difficulties by their late thirties – figures which are considerably higher than traditionally reported, newly published information from the Dunedin Multidisciplinary Health and Development Study shows.
The lifetime experience of a problem with infertility was “common” by the age of 38 in the Dunedin birth cohort, with an infertility problem reported by 22% of the men and 26% of the women.
Infertility was classified as trying to conceive for 12 months or more or seeking medical help to try and conceive, and included fertility difficulties reported when the cohort was aged 38 and also measured when the cohort was aged 32. A fertility problem that was unresolved at age 38 occurred among 40% of affected men and 28% of affected women, and more commonly among men and women who were in their mid to late-thirties when first experiencing this fertility problem.
The findings have recently been published in the international journal Fertility and Sterility.
Dr Thea van Roode, who has been investigating fertility in the Dunedin Multidisciplinary Health and Development Study, a longitudinal study that has followed nearly a thousand Dunedin-born children into adulthood, says: “While the majority of the cohort had become parents by age 38, a substantial proportion still wanted to become parents or have another child in the future when we asked at that time; However, our results highlight this may not be possible.”
She adds: “These findings are important in view of a larger trend towards delaying parenthood. Compared with earlier decades, there is a now a trend in many countries to delay parenthood well past age 30. This is certainly the case in this cohort as at the earlier age 32 assessment only about half had become a parent.”
Professor Wayne Gillett, a fertility specialist and co-author on the paper says it is unfortunate that many men and women are not aware that women’s fertility starts to decline well before the menopause for women.
“And as we found here treatment may not be so successful when women are older. Postponing parenthood may make it difficult for some people to become a parent at all, or have as many children as people would like. Also the financial burden may be high for those who pursue fertility treatments, as publicly funded treatments are not available for those aged 40 or older,” says Professor Gillett.
Associate Professor Nigel Dickson, who has studied the sexual and reproductive health of the cohort for more than two decades says: “We asked about difficulties conceiving when they were aged 32 and again six years later, and found quite a few men and women who reported problems at the earlier assessment did not do so the next time and vice versa. This suggests studies that only question people on one occasion may underestimate the true extent of these problems.”
There are few cohort studies that have explored sexual and reproductive health and behaviour in this level of detail for such a prolonged period.
“We plan to continue the study when the participants are aged 45, and while we hope that those who expressed a desire for more children when asked at 38 will have been successful, unfortunately we doubt if this will be the case for all”.
The Dunedin Multidisciplinary Health and Development Study, which is funded by the Health Research Council of New Zealand, has been able to provide a wealth of valuable information not available from other sources, in part due to the very high retention as a result of the ongoing commitment by the study members.
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