After 46 years of marriage, an Indian woman and her husband, both in their 70s, are celebrating the birth of their first child, following IVF treatment.

Daljinder Kaur is believed to be about 72. Her husband is 79. After two years of IVF treatment, the couple used donor eggs and gave birth to a healthy baby boy.

As the couple nears octogenarian status, Kaur has said he has “full faith in God” that “he will take care of everything.” But when it comes to raising a child—how old is too old?

According to Medical Ethicist Art Caplan, an ethical dilemma arises when parents can’t physically be there for their children. “We should put an age limit on having babies,” Caplan said in an interview with Boston Public Radio on Wednesday. “Not because people don’t want to do it, it’s because you ought to be around to raise the child. If you’re 79 as the dad and 72 as the mom, then the odds are very good that you won’t be there to help that child, or that they’re going to have to take care of you because you’re going to become incapacitated.”

For Caplan, the limit depends on the ability of the parent to raise their children beyond their teenage years. “I know we all want to believe that we’ll live forever and that 60 is the new 28 and all that,” he said, “but the reality is, when you get up to those kinds of ages, you’re going to take care of a teenager at age 90?”

At least one parent must still be around to do some of the parenting, Caplan says. “If you’re a woman and you have a younger boyfriend, and they’re around to raise the kid, okay,” Caplan said. “But if you’re both over 65… you’re supposed to diaper the baby, they’re not supposed to diaper you.”

Medical Ethicist Art Caplan is Head of the Division of Medical Ethics at NYU Langone Medical Center and the co-host of the Everyday Ethics podcast. To hear more of his interview with BPR, click on the audio link above.