WASHINGTON — Michelle Obama says she felt alone after a miscarriage 20 years ago, and she and Barack Obama underwent fertility treatments to conceive their two daughters, according to her upcoming memoir.

In some of her most extensive public comments on her White House years, the former first lady also lets her fury fly over President Donald Trump’s “bigotry and xenophobia” — dangerous, deliberate rhetoric, she wrote, that risked her family’s safety.

“For this,” she writes, “I’d never forgive him.”

But it’s her deeply personal account of her marriage to the future president that shed new light on the Ivy League-educated couple’s early struggle with issues of family, ambition and public life.

“We were trying to get pregnant and it wasn’t going well,” Mrs. Obama, 54, writes in “Becoming,” set for release Tuesday. The Associated Press purchased an early copy. “We had one pregnancy test come back positive, which caused us both to forget every worry and swoon with joy, but a couple of weeks later I had a miscarriage, which left me physically uncomfortable and cratered any optimism we felt.”

The Obamas opted for in vitro fertilization, or IVF, one form of assisted reproduction that typically involves removing eggs from a woman, fertilizing them with sperm in a lab, and implanting the resulting embryo. It costs thousands of dollars for every “cycle,” and many couples require more than one attempt.

The former first lady writes of being alone to administer herself shots to help hasten the process. Her “sweet, attentive husband” was at the state legislature, “leaving me largely on my own to manipulate my reproductive system into peak efficiency,” she said.

“Becoming” is one of the most anticipated political books in memory, ranking at the top of Amazon’s best-sellers on Friday. That’s often the case with the memoirs of former first ladies, including Hillary Clinton and Laura Bush.

But Obama defied her exalted status in the annals of history by cultivating an image of a modern woman with whom many Americans would like to sip wine and chat.

But until now, she’s not extensively shared so many details. Some of her family struggles, such as losing a baby, are known by millions of women.

“I felt like I failed because I didn’t know how common miscarriages were because we don’t talk about them,” the former first lady said in an interview broadcast Friday on ABC’s “Good Morning America.” “We sit in our own pain, thinking that somehow we’re broken.”

Obama said they underwent fertilization treatments to conceive daughters Sasha and Malia, now 17 and 20.

She also writes about falling in love. The Obamas met at the Chicago law firm Sidley Austin LLP, and Michelle was skeptical at first. But she was impressed by Barack’s “rich, even sexy baritone” and by his “strange, stirring combination” of serenity and power.

Their first kiss set off a “toppling blast of lust, gratitude, fulfillment, wonder,” she wrote.

Confronting racism in public life — being the first black first lady, wife of the nation’s first black president — has been a bracing experience, in Obama’s telling. She agonized over what she feared was a cartoonish, racist image. She remembered being labeled “angry” and, by the Fox News network, “Obama’s Baby Mama.”

In the White House, she knew she would be labeled “other” and would have to earn the aura of “grace” given freely to her white predecessors.

As Trump left for Paris on Friday, he chose not to respond to the former first lady, telling reporters, “Oh, I guess she wrote a book. She got paid a lot of money to write a book and they always insisted you come up with controversial.”

Trump instead changed the subject to his predecessor, Barack Obama, saying, “I’ll never forgive him for what he did to our United States military. I’ll never forgive him for what he did in many other ways.”