Katharine McPhee, 34, and David Foster, 68, reportedly want to have kids: Is that even possible?

Katharine McPhee and David Foster revealed their engagement this week on social media, and apparently they can’t wait to get married.

A source tells Us Weekly that the couple plans to have a wedding within the next nine months. “Katharine is telling close friends she doesn’t want to have a long engagement to David Foster,” the source says. “They are very much in love and have previous marriages under their belts.”

The couple also reportedly want to try to have children soon. “David says that Katharine is his true love and muse,” the source says. “They do want to have a family.”

Foster, 68, has five daughters from previous relationships while McPhee, 34, has no children.

While it seems unusual that someone Foster’s age would want to have more kids, it’s not physically impossible at all. “Men continue to make sρerm their whole life,” Lawrence Jenkins, MD, assistant professor of urology at the Ohio State University Wexner Medical Center, tells Yahoo Lifestyle.

That said, men can run into health issues later in life that impact their sρerm count and quality. Having diabetes, high cholesterol, or high blood pressure can cause issues with inseminating, Jenkins says. So can having low testosterone, which is a fairly common issue for older men. Likewise, taking testosterone supplements and medication to try to combat low testosterone can also shut down sperm production, he says.

Older men are also at a higher risk of developing varicocele, a condition in which veins in the scrotum become enlarged, the Mayo Clinic says. This can cause the testicles to be warmer than usual, which may affect sρerm production, motility, and quality, Jenkins says. (Luckily, it’s usually fixed with surgery called a varicocele repair.) This is actually pretty common: Jenkins says it’s one of the first things he looks for in patients with children who are now having trouble conceiving.

Couples should also be aware that children born to older dads are at a greater risk of having certain health challenges. A study of about 2.6 million people published in the journal JAMA Psychiatry in 2014 found that children born to men who were 45 and older had nearly twice the risk of developing psychosis, more than three times the odds of being diagnosed with autism, about 13 times the odds of being diagnosed with attention deficit disorder, and were 25 times more likely to be diagnosed with bipolar disorder than children born to younger men. That doesn’t mean that children born to those fathers are guaranteed to have those conditions — but research does indicate that they are at a higher risk.

“Men over age 50 are considered ‘advanced paternal age’ and their sperm may have a higher risk of new mutations and deletions that can increase the risk of rare genetic disorders,” Eric J. Forman, MD, HCLD, Medical and Laboratory Director at Columbia University Fertility Center, tells Yahoo Lifestyle. “Most of the children are still healthy but the relative risk goes up.”

If you’re part of a May-December romance in which the man is older and you’re having trouble conceiving, the same rules apply for when to see your doctor as when the woman is the older partner, Jenkins says: In general, if the woman is younger than 35, you can wait a year; if the woman is 35 or older, check in with your doctor after six months of trying.

However, Jenkins encourages men who are concerned about their sρerm quality to see their primary care doctor or urologist to check their testosterone level and to conduct a semen analysis at any point. “For any male who has a fertility concern, get your numbers checked,” he says.

If a man has any issues with erections, ejaculation, or having sex—all of which are more common with aging — it’s important to get it evaluated ASAP, Samuel A. Pauli, MD, reproductive endocrinologist and surgical director at Boston IVF, tells Yahoo Lifestyle. It’s also important for men to report any and all medications they’re on. “For men on any prescription medications, it will be important to confirm that none can impact sperm health,” Allison Rodgers, MD, of Fertility Centers of Illinois, tells Yahoo Lifestyle.

Read more from Yahoo Lifestyle:

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• Transgender celeb Laverne Cox talks about her greatest challenge: ‘Getting out of my own way’

• Country star Kelsea Ballerini on success: ‘The overnight sensation thing … doesn’t exist’

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