For Danish couples, the chance of having to try for more than a year to conceive triples if you are obese
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PARIS: Love handles might help couples get a better grip, but all that excess fat could dampen their chances of having a baby, a new study has shown.
Researchers monitoring nearly 48,000 couples in Denmark between 1996 and 2002 found that when both parents were clinically obese, the risk of having to try for more than a year before conceiving nearly tripled.
The odds improved somewhat when the prospective parents were one overweight, but even they had to persist in their efforts longer than their leaner counterparts.
Obesity could even have a demographic impact in countries where the problem of fat has taken on epidemic proportions, said the study published this week in the British journal Human Reproduction.
"If obesity actually is a cause of [low] fecundity … This reduced capacity to reproduce could become a serious public health problem," said lead author Cecilia Ramlau-Hansen, an epidemiologist at Aarhus University in Denmark. "The heavier the population gets, the more problems we would see with infertility," she said.
Earlier research had already established a clear link between too much fat and levels of fertility hormones: In women, excess body fat has a negative impact on ovulation and conception; in men, it is linked with decreased semen quality and the level of reproductive hormones.
But this is the first study which looked at the conception rate among obese couples, who are increasingly common.
In the United States, 30 per cent of adults - some 60 million people - are clinically obese, according the US National Centre for Health Statistics. Within certain demographic groups, notably African-Americans, the rate is even higher.
In Europe, Britain tops the list with 23 per cent, nearly twice the rate in Germany, where 12 per cent tip the scales into obesity, according to the Organisation for Economic Cooperation and Development (OECD).
The benchmark for obesity is the body mass index (BMI), defined as one's weight in kilograms divided by the square of one's height in metres. A BMI from 18.5 up to 25 is considered in the healthy range, from 25 up to 30 is overweight, and 30 or higher is obese.
The authors add a word of caution, saying they did not know how often the couples in their study had sex. "We cannot exclude that infrequent intercourse has delayed conception in overweight and obese couples," they said.
In other words, more fat could mean less sex - so the fertility problem could lie elsewhere.
More information:
Subfecundity in overweight and obese couples, Human Reproduction
