It's not a single book but is the first book of the Accidental Pregnancy series.

Nate Nara is the CEO of Nara enterprise who had everything in his life: good looks, fame, wealth, and a beautiful wife, but the only thing he wants more than anything is to have a family. He wants to have his own family and his own children. But he lost the ability to become a father because of Cancer. So he tried to have the child by using the insemination method. 

 Sadie Smith is planning to go to New York after one month for her studies and she has just started working in his company. She goes to visit the gynecologist for a check-up but gets inseminated by mistake because a nurse misplaced the files and sends her to an endocrinologist by mistake. 

What will they do when they know about it? And will her mother believe let her keep a baby or not? What will she do then? Will Nate's wife gives him a divorce or and late they are happy or will she get him back?