They may already be parents to a whopping 19 children, but Michelle and Jim Bob Duggar would gladly have more "if God saw fit to give us one."

In a sneak peek of tonight's 19 Kids & Counting, the couple visits a fertility doctor to find out whether it would be safe for Michelle to have another child.

"We would love more children," the 47-year-old matriarch says in the preview. "I just want to make sure that I am ready to catch a baby if that would happen."

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The Duggars meet with Dr. Paul Wendel, an OB-GYN in Little Rock, Ark., who specializes in high-risk pregnancies and is familiar with the challenges Michelle faced during her last two.

Josie, the family's youngest child, who is now a healthy 4-year-old, was born three and a half months premature after Michelle developed a life-threatening bout of preeclampsia. When pregnant with her 20th child in 2011, the mom suffered a miscarriage at 19 weeks.

"We do see occasionally pregnancies in women who are 47, 48, 49, even 50 but they are very unusual," Dr. Wendel informs the couple.

Michelle, who chooses not to use birth control, is leaving the future entirely in God's hands. "If I am in that season of life where we're not able to have any more, then I'm fine, I'm happy with that," she says.

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