LEONARDO DICAPRIO is under pressure to have a baby because his mom is desperate to be a grandma!

The “Titanic” heartthrob, 38, has been playing the field since splitting with supermodel Erin Heatherton last November.

But his latest squeeze, 21-year-old German model Toni Garrn, may be just the woman to make the lifelong bachelor take the leap into fatherhood.

“Leo is quite smitten with Toni,” revealed an insider. “She’s just his type, and he’s said quite seriously that she has the perfect genes for motherhood.

“Toni has been modeling since she was 13 and is very mature for her age, so it’s not as crazy as it sounds. She’s head over heels for Leo, so it wouldn’t be a big shock if she went for it.”

And nothing would make Leo’s mom, Irmelin, happier.

Another insider says she doesn’t really care WHO Leo’s baby mama is, just as long as she gets to be a granny ASAP!

“Leo says his mom’s expectations are hilariously low,” said the insider. “She just wants a grandkid to spoil and cuddle. Although Leo’s cool with the concept of fatherhood, he’s still shy about marriage because he’s worried about losing a chunk of his fortune and precious art collection should it end in divorce.”

Leo tries to spend a lot of time with his mom, 68, and she’s said to have a huge influence on him.

“Irmelin really wanted him to marry Gisele (Bundchen) when they were dating a few years ago, but now it’s clear she wants grandkids more than she wants a daughter-in-law,” said the insider.

“And Leo’s actually thinking about it. If anyone can persuade him to settle down, it’s Irmelin. He adores her.”