The story of two teenage girls who discover they were accidentally switched as newborns in the hospital. Bay Kennish grew up in a wealthy family with two parents and a brother, while Daphne Vasquez, who lost her hearing at an early age due to a case of meningitis, grew up with a single mother in a working-class neighborhood. Things come to a dramatic head when both families meet and struggle to learn how to live together for the sake of the girls.

Switched Before Birth follows Olivia Crawford and her husband Brian, who after multiple miscarriages, numerous failed IVF trials and stretching themselves to the limit financially, finally receive the joyous news that she’s pregnant with twins. While going through her latest round of IVF, Oliva meets and becomes fast friends with Anna Ramirez, who is struggling to have a child after years of focusing on her successful restaurants. When Anna becomes pregnant as well, the ladies celebrate and begin to prepare for their babies. Olivia is also there for Anna when she suffers a devastating miscarriage and struggles to move forward while her marriage to restaurateur Gabe Ramirez crumbles. When Olivia and Brian finally welcome their twins Olivia’s life feels complete, but the happy couple’s world is turned upside down when they discover that not only are the babies not twins, but one of the babies is also biologically Anna and Gabe’s that was implanted into Olivia by mistake.

Two couples discover they may not be have found "the one" after all, and whether they're ready to admit it or not, their friends will give them the push they need to find true love.