Rod Stewart's Wife Penny Lancaster Breastfed Stepdaughter Kimberly's Baby Since She Had Low Milk Supply: 'Real Motherhood Bonding Moment'

Rod Stewart's wife, Penny Lancaster, revealed she helped breastfeed stepdaughter Kimberly Stewart's daughter, Delilah, when the socialite wasn't producing enough milk.

Penny shared the surprising confession in a new interview, noting she gave birth to a baby boy six months before Kimberly, now 46, became a mother in 2011.

"It was a real motherhood bonding moment. The breastfeeding nurse said, ‘In a perfect world, you’d know someone who’s breastfeeding’ — and everyone turned to look at me," Penny, 54, recalled to a publication.

"I remember thinking, ‘What’s the most important thing for this child?’" she continued. "I knew my milk would give her the nutrients and antibodies she needed."

Penny, who shares sons Alastair, 19, and Aidan, 14, revealed in her new memoir, Someone Like Me, that at first, her husband didn't want any more children when they met, as aside from Kimberly, he shares son Sean with ex Alana Stewart and has four other kids with multiple other women.

In the tome, Penny recalled how the musician, 80, once bluntly told her, "I don’t want to get married and I don’t want any more babies."

However, in 2004, the "Sailing" singer had a change of heart. "Suddenly, Rod turned to me and went, 'Let’s make a baby.' I was like, ‘Oh my God, oh my God, oh my God!’ It’s all I wanted," she spilled.

While the couple conceived shortly after, Penny suffered a miscarriage.

After seeking out advice from a doctor, Rod was told he had to stop wearing his signature tight pants.

"We conceived the night he proposed to me," she revealed, with couple tying the knot in 2007.

Penny underwent IVF to welcome their second child.

Elsewhere in the interview, Penny chatted about aging and longevity, insisting her spouse isn't going anywhere anytime soon.

"Rod is very vigilant with his health," she pointed out. "He exercises, takes care of his diet and has all the regular health checks."

"He decided he wanted to try and be the fastest 80-year-old, so he built a 200m sprinting track in our garden so he could practice. He’s just like a teenager," the mother-of-two quipped. "He’s living it to the full. We’re trying to keep up with him but he sets the bar. He’s promised me 20 years, so I’m seeing 100."

"I guess everyone has their time. Rod is very blasé about [mortality]," Penny added. "He feels like when the time’s up, the time’s up, but he’ll go in a flame of laughter and fun."