The variability of menstrual cycles might affect the accuracy of fertility apps: study

New research has found that women's menstrual cycles can vary considerably, with very few lasting the textbook 28 days. — AFP Relaxnews

New European research has found that only 13% of women have menstrual cycles lasting 28 days, which researchers say could help couples better understand when pregnancy is more likely to occur.

Led by University College London (UCL) and Natural Cycles, a contraceptive app, the new study is one of the biggest to date to look at menstrual cycles, analysing data gathered from the app on over 600,000 menstrual cycles and 124,648 women aged 18 to 45 from Sweden, the US and the UK.