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A growing number of women are using it for another purpose: helping them get pregnant, avoid pregnancy, and get general sex advice.
Glow, a startup created by PayPal mafia member Max Levchin, offers such apps.
Every now and then Glow polls the more than 4 million women who use its apps about sexual topics. It also looks at the anonymized data collected by its apps to discover insights into women's sex lives.
Glow just studied how alcohol influences sex and confirmed that there's a definite correlation between how much a woman drinks and the kind of sexual behavior she might regret.