A speaker at major women's events nationwide, where this year she'll be speaking before more than 100,000 women, Kingsbury said: "The issue of post-abortion syndrome, or PAS, comes up often. Women are literally buried beneath a guilt they've carried for years and in some cases decades."

After writing 40 novels on a wide range of subjects, Kingsbury was motivated to write a book on PAS after hearing the song "Red Ragtop" by country music artist Tim McGraw.

"Around the country, some radio stations banned the song," Kingsbury said in a letter to readers at the end of Shades of Blue. "They thought it held a pro-abortion message. But the song spoke to me in the exact opposite way. I believe ‘Red Ragtop' is a song about regret, about a guy being years removed from such a decision and still knowing that it would haunt him all his life.

"The first time I heard that song, I knew that one day, if God allowed it, I would write a novel about a guy like that-a guy smothered with regret," added Kingsbury, who as a teenager took a friend to have an abortion.

In researching for the book, Kingsbury was able to contact her friend and apologize for her role in the abortion. Shades of Blue's plot centers on New York ad agency rising star Brad Cutler, who is haunted by his past decision with a high school girlfriend.

The book will release simultaneously in hardcover for $21.99 and in softcover for $14.99.