They have put their faith in God. He will decide how many children they will have. They have enough faith to KNOW that whatever comes, they will work it through with each other and with God's help.
What horrible, selfish people...
No, God isn't having unprotected sex with Mrs. Duggar making the decision of how many kids she will have. They are exercising their own will and desires.
We hope all babies are born healthy, but why risk leaving the family with a huge responsibility after already having successfully so many children?
Rolling the dice at an older age when handicapped children are more known to come is very selfish IMO. Especially when they already have a boat load of kids. Why take the chance of passing on a boat load of trouble to the healthy kids for life if they now get a problem child due to age?