Surrogate motherhood has been a controversial practice in the United States ever since the widely-publicized "Baby M" case in 1986. That's when surrogate mother Mary Beth Whitehead fought an unsuccessful court battle for custody of a child she was paid to bear for another couple. Since then a quiet and fundamental change has swept through the business known as "commercial surrogacy." Most surrogate mothers today are not genetically related to the children they carry. That fact may increase both the number of babies born through surrogacy and the legal security of the arrangements. Minnesota Public Radio's Stephen Smith has more in the next part of our ongoing series, "The Fertility Race."