Mom-to-be Jessica Biel is glowing, but behind the scenes, the “7th Heaven” beauty is concerned that husband 
Justin Timberlake isn’t pumped for playing dad!

“This should be the happiest time of their lives, but Jessica worries Justin isn’t ready to give up touring,” a close friend dished.

While the couple have yet to make an official announcement, the actress, 32, has been seen in maternity wear and sporting a growing baby bump on the set of her film, “The Blunderer.”

Another friend said Jessica is “beyond excited” about becoming a mom – a story broken in The ENQUIRER months ago – but is concerned because Justin’s been on his tour for over a year.

“They’ve spent little time together during Jessica’s pregnancy,” the pal said.  While Jessica has begged Justin, 33, to come home, another friend said the singer’s been business-as-usual on tour.

“Justin pretends he doesn’t have a care, but you can see how antsy he is. He knows it won’t be long before his life changes.”

Jessica wanted to “start a family,” said a friend. “Now she’s concerned it might be more than Justin can handle.”

Meanwhile, Jessica’s getting support from Justin’s mom, Lynn Harless. “Lynn’s totally confident he’s going to be a great dad!”