I think. From what I've read (I have never watched the show-but have now watched a few snippets as part of the reporting on this) it's almost like she's addicted to having children. This is where she gets her identity. And it's been very affirming for her I think. She's an icon for the Quiverfull movement and has received awards, like from the disgraced Doug Phillips who was head of Vision Forum before his sexual assaults of their nanny came out.
http://www.christianpost.com/news/duggar-familys-close-relationship-with-vision-forum-founder-doug-phillips-and-wife-highlighted-after-scandal-108697/
As with many of these extremist families, the parents did not suffer the same restrictive childhood. Michelle was a CHEERLEADER who now laments how she defrauded men with her outfits. And dancing, it's real bad too!
http://www.beliefnet.com/Entertainment/Celebrities/2009/10/Michelle-and-Jim-Bob-Duggar.aspx?p=9
There's some evidence Michelle was troubled in some way as teen-
she had admitted to having suffered from bullemia.
http://www.foxnews.com/entertainment/2015/03/10/michelle-duggar-talks-about-her-struggle-with-eating-disorder/
And she met Jim Bob who was more religious and then they married and after a miscarriage, decided God punished them for using birth control. And then they steadily went further off the rails until they became completely home centered and modesty and purity obsessed. Their family was stuck at home for everything, school, church, friendships which were only between siblings. A totally different childhood than either of the parents had. That's what gets me the most about these people. It's fine to become an extremist as an adult if that's what YOU want. But the children have no choices at all about anything. And they even forced to appear happy at all times. I think their whole existence is abusive and cultish.
http://hedua.com/blog/they-smile-but-do-they-laugh/
It was also clear she really had little meaningful interaction with the children after they were babies. She is the babies buddy until they are weaned and then they get handed off to an older sibling buddy (which only seem to be the girls of course-I could be wrong) while MD works on the next blessing. Apparently the buddies do everything for their charges, dress, feed, school, music lessons etc, this wasn't just some vague responsibility like when they're traveling. This was an actual job-to take care of a child, to do that which parents would normally do.
I do think there is probably something that needs to be diagnosed about MD. Even after the miscarriage and the preemie birth she had she is still trying to have more kids. Why aren't those events "signs from God" that they need to STOP? Why do they only ever hear messages from God that confirm what they what to do? It's just amazing that their God thinks exactly like they do....