This brief estimates the prevalence of, perceptions about, and reported effects of unplanned births among reproductive-age women in 2016. About one third of all women and six in ten women who had given birth reported experiencing an unplanned birth. Most women perceived unplanned births to have negative effects on a woman’s life, particularly her socioeconomic well-being. Negative perceptions were more common among white women, higher-income women, more educated women, and women who have not experienced an unplanned birth. These findings underscore the importance of access to family planning services, which allow women to plan their pregnancies and prevent unplanned births.