Obesity rates increased slightly between 2014 to 2021, but I’m not sure that will account for doubling of mortality rate. It could mean that more obese people are having kids than before, but that would be far from trivial to prove
It seems reasonable that there would be increased risks during a pregnancy when the body wasn't prepared to get pregnant without intervention.
Unplanned pregnancies might happen to people who aren't ready to have a child, physically and mentally - or who don't have easy access to medical care.
IVF, in contrast, only produces planned pregnancies, and only in people with easy access to medical care.
I agree with GP that IVF probably provides motherhood to a lot of people who have preexisting medical issues.
IVF on the other hand very likely skews older, and I wonder if those needing IVF are also less healthy on average than non-IVF.
The human body wants to reproduce as its default state. When it can't, there must be physical or environmental reasons (or the likely rare genetic condition that can be a primary cause of infertility).