The market is booming in apps news hich offer women the chance to monitor the cycles of their monthly periods.
There are thought to have been as many noticias as 200m downloads of period tracking apps worldwide. But a leading UK medical royal college has warned that women should not rely on them as a form of contraception.
And privacy campaigners say users should be wary of what data they might unwittingly be sharing when they download some apps.
A search for period tracking apps will quicklynoticias del mundo bring up dozens of offerings - some with charts, others illustrated with pink tulips or lilac flowers.
In the health and fitness category, period trackers come second only to apps which monitor running.
Amy Worsfold, from Greenwich, south-east London, has used different trackers for three years. She is a soprano opera singer.
Amy told me: "When you are starting world news your period or you're pre-menstrual, the hormones that rush around your body affect your larynx in ways that are detrimental to your singing voice.
"I use the app to avoid auditions, premieres or really important performances on those days if I can."
