I’m not saying it couldn’t happen concurrently, but probably consecutively.
With the wonders of life-saving vaccines for all, why should mothers need to have so many children to ensure at least a couple lived to adulthood? Oh…
Realistically it’s probably neither perfectly concurrently nor consecutively. Concurrently is unlikely but possible, but no woman is fertile long enough to fully raise 6 children fully consecutively. Heck, no woman lives long enough to do that. That’s 120 years not counting pregnancy.