In Utah and Mississippi, gay couples are banned from adoption. A number of other states have laws like Ohio's that allow one partner to adopt a child as an individual but do not allow the couple to adopt, The New York Times reports.
An Arizona law recently took effect that requires married heterosexuals to get preference as adoptive parents.
"It's two steps forward, one step back," said Ellen Kahn, director of the Family Project at the Human Rights Campaign.
Gary Gates of the Williams Institute on Sexual Orientation Law said in 2000, only 8 percent of gay couples who were raising children had an adopted child. Nine years later, that had risen to 19 percent. He said about 4 percent of adopted children have a gay parent.
Matt and Ray Lees, who live in Worthington, Ohio, near Columbus, have eight adopted children. Matt Lees is the legal father of three, while his partner has legally adopted the five children of a drug-addicted woman. They have also enacted custody agreements to protect the children in case something happens to one of them.
Matt Lees said many people thought they were "crazy" to take on such a large family.
"It was the best way we could think of spending the next 20 years of our lives," he said.