The "Sister Wives" clan is expanding their brood.

Kody Brown and his fourth wife, Robyn, are expecting their second child, the couple told PEOPLE.

"We are so happy to announce an eagerly expected new member of the Brown family!" they told the mag.

The baby will be number 18 for the polygamist family who have their own show on TLC. Kody and Robyn share one biological child together in addition to Robyn's three kids from a previous marriage.

Kody has one child with his first wife, Meri, six with his second wife, Janelle, and six with his third wife, Christine.

Kody's trick to helping his wives through their pregnancies? "I always try to be kind and tender, but when a woman is expecting, you have to be ultra-sensitive. And always do the dishes."

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