Losing interest, a lack of time and feeling like they weren't good enough means 53 per cent of girls give up sport once they finish school and compulsory PE lessons.
Others don't continue into adulthood because they had little or no encouragement from others, wanted to focus on other things or due to their friends giving up as well.
The study, of 1,000 girls aged 16-24 was commissioned by feminine care brand, Always, to launch its #LikeAGirl campaign.
It also emerged that while 88 per cent believe society encourages boys and men to take part in sport, just 35 per cent believe the same is true of girls and women.
British cycling star and Olympic gold medallist Laura Trott, who is partnering with Always for their #LikeAGirl campaign, said: "We all go through it, but puberty can be such a challenging time for girls, you suddenly feel really self-conscious about lots of things and start thinking you can't or shouldn't do certain activities.
"I remember kids making fun of me for cycling and wearing a helmet and that would really knock my confidence.
"But playing sport taught me that by believing in myself, and never quitting, you can achieve great things.
"That's why I am proud to be supporting the Always #LikeAGirl mission to help stop the drop in confidence girls experience at puberty.
"Sport really is one of the strongest confidence building activities and as a female athlete competing in the Olympic Games I want to encourage and inspire girls everywhere to keep playing #LikeAGirl and never quit."
Losing interest or no longer finding it fun is the most common reason for girls not continuing sports past their teenage years, followed by a lack of time and becoming more self-conscious of their body during and after puberty.
Needing to focus more on their school work, job or other areas of their lives, lacking the confidence to believe they could succeed at sports and thinking there was no career or profession in it for them also feature in the top ten.
Worryingly, more than one in twenty young girls even claimed they were teased by others for their interest in sport, leading them to quit rather than continuing into later life.
Half of young girls believe becoming more self-conscious about their body during puberty prevents young women from playing sports once they finish school.
And almost a third put girls' dwindling participation in sports as they get older down to the fact there is little or no respect for females in sports.
Other factors behind the lack of girls playing sports are that they are being encouraged to do other things instead, the belief that there is no career path for women in sports and the lack of availability of sports for women in schools and communities.
One in four even believe a lack of media coverage on women's sports are a factor, along with a lack of encouragement from friends and family, no financial support and a lack of role models.
Top ten reasons girls stop playing sports
1. I lost interest or no longer found it fun
2. A lack of time
3. I become more self-conscious of my body
4. I needed more focus on my school or job
5. I wanted to focus on other things
6. I lacked the confidence that I could succeed at sports
7. I wasn't good enough
8. A lack of encouragement
9. It couldn't be a career/profession for me
10. My friends quit playing