Hillary Duff is holding onto her baby's umbilical chord

New mom Hilary Duff, 24, cannot bring herself to let go of her four-week-old baby, Luca Cruz — not even the parts of him that are falling off. “You know what was a big milestone? The belly button falling off," Duff told People, referring to the baby's umbilical chord. "That was a huge one. And then I wanted to keep it but my husband was like, ‘No, that’s gross, you can’t keep it!’ I’m like, ‘I’m totally keeping it,’ and I secretly kept it.”

That husband is Mike Comrie, who has been splitting the caretaking with Duff. “He’s really hands-on during the day,” the actress and singer said of Comrie. “But at night, I’m the only one that can feed the baby. I wasn’t going to make him suffer just because I was having to get up.”