Kody and Meri on TLC's "Sister Wives." How does that saying go? If you're old enough to have sex, you're old enough to talk about it. Well, in the case of "Sister Wives" stars Kody Brown and wife No. 1 Meri, that may not hold true despite their maturity -- or seeming lack thereof when it comes to the subject of sex. In an exclusive sneak peek TLC shared with TODAY.com of Sunday's new episode, the couple are at their fertility doctor's office when an unsurprising statement (considering the nature of the visit) brought about an unexpected reaction. "It looks like you all have been trying to get pregnant for a while," noted Dr. Littman. Meri immediately launched into awkward giggles. "Well, we haven't been trying real hard, but I mean, we haven't been trying to stop it -- ever," replied Kody, which resulted in his wife laughing uncomfortably. Meri later went on to explain that she wasn't expecting questions about their sex life during the visit to the fertility specialist. "It's a very, very, very private and personal subject," Meri said. We just do not talk about it. Check it out: Meri's desire for more children hasn't been a secret. Last season, wife No. 4, Robyn, offered to be a surrogate after Meri experienced trouble conceiving again (she has one child, a teenage daughter). Sunday's episode will also feature Meri and Kody revealing that she miscarried about 10 weeks into her pregnancy four years ago. "Sister Wives" airs on Sundays at 9 p.m. on TLC. Do you think the presence of the cameras made Meri more uncomfortable when discussing the subject?