04/09/2011 at 12:45 PM EDT
Kody Brown, the shaggy-haired patriarch who stars on TLC's Sister Wives
, and his fourth wife Robyn, are expecting a baby.
"You should have seen the look on his face when we found out," Robyn tells PEOPLE exclusively. "It was priceless."
The baby, due in mid October, will be the first for Kody and Robyn, who has three children from a previous marriage. This will be the 17th child for the family, which includes Kody's three other wives and their kids. Kody and Robyn, who moved to Las Vegas with the rest of his fundamentalist Mormon family in January, were married last year during the first season of Sister Wives
. Kody is also married to Meri, his only legal wife, Janelle, and Christine.
"I'm overjoyed," says Kody, 43, about the impending arrival of the new family member. "This connects Robyn and I together in a way that nobody can take away."
From the sounds of it, Robyn, 31, will have no problem finding helpers to assist her once her baby is born. "The other day I wanted a sip of iced coffee," she recalls, "and Aspyn and Maddie (two of her sister wives' teenaged daughters) were with me and said, 'Oh no you don't. You shouldn't be drinking coffee.' It was cute. They're so protective. And I can't even tell you how many times a day I have kids kissing my belly."
Both Robyn and Kody report that the only rough spot in the pregnancy has been agreeing on where to have their child. "If Kody had things his way, he'd have me go to the hospital," says Robyn. "But I just like having home births. I'm not big into sitting around in a hospital."
So what has Kody learned after surviving 14 of his wives' previous pregnancies? "I try to always be kind and tender, but when a woman is expecting, you have to be ultra sensitive," he says. "And always do the dishes."
Tune in to the next episode of Sister Wives Sunday at 9 p.m. on TLC