Moderate exercise linked to quicker conception

Moderate exercise is tied to greater success among women trying to get pregnant, but those who work out vigorously take longer to conceive, an international study has found. “This study is the first to find that the effect of physical activity on fertility varied by body mass index,” said lead author Lauren Wise, a reproductive epidemiologist at Boston University. Body mass index (BMI) is a ratio of height to weight. Researchers in the US and Denmark followed more than 3,500 Danish women aged 18 to 40 who were trying to conceive over the course of a year for the study, published in the journal Fertility and Sterility. All reported being in a stable relationship with a male partner and were not receiving any fertility treatments. Participants estimated the number of hours per week they had spent exercising in the past year, as well as the intensity of their workouts. Over the course of the study, nearly 70 per cent of all women became pregnant. The researchers found that moderate exercise, such as walking, cycling or gardening, was associated with getting pregnant more quickly for all women, regardless of weight. Women who spent more than five hours per week doing moderate exercise were 18 per cent more likely to become pregnant during any given menstrual cycle than women who performed moderate exercise for less than an hour each week. However, normal-weight and very lean women who reported high levels of vigorous exercise, such as running or aerobics, took longer to get pregnant. Those who exercised vigorously for more than five hours each week had a 32 per cent lower chance of becoming pregnant during a given cycle than women who did not exercise vigorously at all. There was no association between vigorous exercise and the time it took overweight or obese women — those with a BMI of 25 or greater — to become pregnant.