In the course of the research, the researchers distributed questionnaires to 3,628 women within the age bracket of 18 to 40 years.
This distribution was done over the internet.
As a rule, the women should not be undergoing any fertility treatment.
And they have to be in stable relationships with male partners and have plans to get pregnant.
Information on height, reproductive and medical history, body weight, lifestyle, and behavioral details were collected first from https://www.nih.gov/.
Then questionnaires were sent via email to them for every two months for a period of 12 months or till the woman conceives.
The first question asked these women was the average number of hours they exercised per week.
Also, they were also to answer questions on the kind of physical exercises they did, if it was simple or a difficult activity.
Exercises such as running, fast cycling, gymnastics, and swimming were considered strenuous.
But brisk walking, leisurely cycling, gardening, and golfing were considered to be less strenuous exercises.
Participants were classified based on the level of exercise performed and results evaluated according to body mass index (BMI, a ratio of weight to height).
Any BMI over 25 is considered overweight or obese.\