What to Expect When You're Expecting

What to Expect When You're Expecting is a pregnancy guide, now in its fifth edition, authored by Heidi Murkoff and Sharon Mazel and published by Workman Publishing. Its first edition, authored by Murkoff, Arlene Eisenberg, and Sandee Hathaway, was originally published in 1984. The book consistently tops The New York Times Best Seller list in the paperback advice category, is one of USA Today's "25 Most Influential Books" of the past 25 years and has been described as "the bible of American pregnancy". As of 2021, per the publisher and the author's agent, over 22 million copies were in print in . According to USA Today, 93 percent of all expectant mothers who read a pregnancy guide read What to Expect When You're Expecting. In 2005, WhatToExpect.com launched. The What to Expect mobile app launched on iOS in 2009 and Android in 2014. In 2012, What to Expect When You're Expecting was adapted into a film released by Lionsgate.