She tells ABC in an interview aired on "Good Morning America" she felt like she "failed because I didn't know how common miscarriages were because we don't talk about them".
She writes that she will "never forgive" Trump for putting her family at risk by promoting the conspiracy theory, as reported by the Washington Post.
The memoir fulfills half of an agreement that publisher Penguin Random House reached with her and the former president after he left office under which the couple will each publish one book, reportedly for a sum worth more than $60 million.
In audio from the book obtained exclusively by ABC News, Michelle Obama says: "What if someone with an unstable mind loaded a gun and drove to Washington? And I will forgive him, never".
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"The whole [birther] thing was insane and mean-spirited, of course, its underlying bigotry and xenophobia hardly concealed", Obama wrote, according to a Washington Post review.
"I was female, black, and strong, which to certain people. translated only to 'angry, '" she explained.
Obama also reveals that she felt resentful about administering her own IVF shots while her husband was away working, writing, "None of this was his fault, but it wasn't equal, either".
As BBC reports, Michelle Obama's candid memoir reveals that she suffered a miscarriage before giving birth to her daughters. The book is scheduled to be released this Tuesday in the US.
Among those struggles were her and Barack's challenges starting a family. She writes of Trump following Clinton around the stage, standing nearby and "trying to diminish her presence". "But it was also unsafe, deliberately meant to stir up the wingnuts and kooks", Obama reportedly writes.
Finally, Obama also reveals that she and Barack underwent marriage counseling, which should shed some light on the hard work it takes to achieve what looked, in former White House photographer Pete Souza's photos, like an effortlessly ideal marriage.
"I've never been a fan of politics, and my experience over the last ten years has done little to change that", she writes according to the Post.