Are you a female athlete or just someone who likes challenging workouts -- who also wants to get pregnant? It may make sense to ease off a bit as you try to get pregnant. New research from the Norwegian University of Science and Technology (NTNU) shows that the body may not have enough energy to support both hard workouts and getting pregnant.

Roughly seven per cent of all Norwegian women are believed to have infertility problems, which means that they are unable to become pregnant during the first year of trying - even if they might later become pregnant.

Infertility can have many causes, both medical and lifestyle-related. Known risk factors include smoking, stress, and alcohol. Being extremely under- or overweight can also play a role.

It is known, however, that elite sports women have more fertility problems than other women. But does extreme physical activity play a role in fertility among other women as well? NTNU researchers examined precisely this question in a study involving nearly 3,000 women. They found that overly frequent and hard physical exercise appears to reduce a young woman's fertility. But the decrease in fertility probably lasts only as long as the hard training.

Two vulnerable groups

The study was based on material from the Health Survey of Nord-Trøndelag from 1984-1986 and from a follow-up survey in 1995-1997. All of the women who participated were healthy and of childbearing age, and none had a history of fertility problems.

In the first survey, women responded to questions about the frequency, duration and intensity of their physical activity - and ten years later were asked questions about pregnancy and childbirth…