"What if that person went looking for our girls?" she writes.
Michelle Obama said that although she'd given him her blessing to run, she didn't think he'd win. That's often the case with the memoirs of former first ladies, including Hillary Clinton and Laura Bush.
Throughout her husband's life in politics, she fought to balance public and private needs, and to maintain her self-esteem.
She said: 'I felt like I failed because I didn't know how common miscarriages were because we don't talk about them.
Michelle Obama says Trump's viscious campaign was "deliberately meant to stir up the wingnuts and kooks" and she always felt threatened that one of these wingnuts would take out their anger on her husband or children.
IVF is one form of assisted reproduction and typically involves removing eggs from a woman, fertilizing them with sperm in a lab, and implanting a resulting embryo into the woman's uterus. As she became more well-known, however, the attacks from the right began. She also reveals for the first time that she ultimately resorted to in vitro fertilization to conceive her two daughters.
She also thought his picture had a "whiff of geekiness".
In the memoir, Michelle also details the early days of her relationship with her husband, including their first kiss. She agonised over what she feared was a cartoonish, racist image. Mr Obama eventually released his birth certificate which proved he was born in the USA state of Hawaii. Donald Trump, with his loud and reckless innuendos, was putting my family's safety at risk. How she met her husband and how she coped up being one of America's first lady for years - something that is now written in books for a lifetime. "And we get help with our marriage when we need it", she writes.
U.S. President-elect Donald Trump greets outgoing first lady Michelle Obama.
She admitted that stuff like that "hurts", even if she was seen as one the most handsome and intelligent women in the country. She remembers how her body "buzzed with fury" after seeing the infamous "Access Hollywood" tape, in which Trump brags about sexually assaulting women.
Mrs Obama launches her promotional tour on Tuesday not at a book shop, but at Chicago's United Centre, where tens of thousands of people have purchased tickets - priced from just under 30 dollars (€26) to thousands of dollars - to attend the event moderated by Oprah Winfrey.