The pair already have six dogs and three cats in their home but the actress is determined to have more.
She told E! Online: "I pretty much now defer to my husband, who has put the kibosh on any more.
"He says, 'You know, Katie, we already have 12 heartbeats in this house and that's a lot of responsibility', but it's hard - It's really hard to say no."
Heigl recently revealed that she found it difficult to bond with her baby.