When Andrea Ott-Dahl agreed to serve as a surrogate mom to a Silicone Valley couple, she and her longtime partner, Keston Ott-Dahl, had no idea it would turn into one of the most difficult – but ultimately rewarding – experiences of their lives.



Two months into Andrea's pregnancy in 2012, prenatal tests showed that the baby had Down syndrome, in addition to other complications, Keston, 50, tells PEOPLE.



Doctors had said that the unborn baby, nicknamed "Peanut," would most likely suffer from blindness, autism and a severe heart condition – if she survived birth.



"We were devastated," Andrea, 34, tells PEOPLE.



What happened next rocked them even further. The couple, who had contracted Andrea to be their surrogate, wanted her to abort the baby. So did Andrea's doctor, who said he could perform a termination the day Andrea had the ultrasound showing the baby had health complications, says Keston.



"The intended mothers didnâ€™t want the baby and told us it was their choice to terminate, and their choice alone," says Keston.



Andrea and Keston did not agree with them. "I told them, 'The decision is whether you want to keep this child or not, but it's not your decision whether or not to terminate this child,' " says Keston.



The intended mothers briefly threatened a lawsuit to try to force Andrea to terminate the pregnancy, which they failed to pursue. "Basically, we decided we were going to save Peanut," says Keston. "We couldnâ€™t give up this baby. We knew we were doing the right thing."



Keston and Andrea chronicle their emotional journey about deciding to keep their now 2-year-old daughter, Delaney Skye, in an upcoming memoir, Saving Delaney: From Surrogacy to Family, out April 12.





"A lot of people share this same story," says Keston. "It's almost like we didnâ€™t have a choice to terminate, but now we know we actually do have a choice."





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A Beautiful Life

When the doctor confirmed that the baby had Down syndrome, Keston and Andrea researched prenatal interventions to help bolster the baby's health and brain function, such as choline supplements, which Andrea took throughout her pregnancy and while breastfeeding.



They also watched hours of videos about children and adults with the chromosomal disorder.



"We saw that they were going to college, that they had able employment, that they were getting married and that they were doing everything that everybody else can do with early intervention and we decided that that's what we're going to do," says Keston.



"We said that we were going to give Delaney every opportunity to thrive."



When Delaney was born on July 2, 2013, she had a heart problem that was surgically corrected when she was three and a half months old. "Thatâ€™s the only health issue that she's ever had," says Andrea.



Today, Delaney delights in running around and playing in the couple's sprawling, 100-year-old refurbished house in the San Francisco Bay area she shares with Andrea's two children from a previous relationship and Keston's two grown children from another relationship. "We have a full house," says Keston. "We wouldnâ€™t have it any other way."





Delaney is developmentally and cognitively right on target with babies without her disability," says Keston, who attributes this in part to the early intervention the couple began when Andrea was pregnant and the NuTriVene D supplement for children with Down syndrome that Delaney takes. (Pregnant women should consult with their doctors before taking any supplements or medications.)



"Delaney did not get the memo that she has Down syndrome," says Keston. "It does not limit her. She talks and she says sentences at two. She plays video games and Barbies with her siblings. She loves to dance when Ellen DeGeneres is on TV. When we watch her show, Delaney's got to get up and bust a move with Ellen."



Moved by how much Delaney changed their family's life for the better, the couple started a Facebook page about Delaney, which has thousands of fans.



"People follow her every day and love her," says Keston. "People say how inspirational she is and how much they love watching her grow up."



