Not saying it was the only cause in this country but it’s still a big one. And you won’t see it discussed in the media because to do so would be admitting that they helped the establishment use children as pawns and cannon fodder and that women were manipulated to play their part.
You could watch a teevee in the 90’s for 30 minutes without hearing the words “deadbeat dad” five times so they could railroad their child support database into federal law. That the one everyone goes into in order to get a job, even if you never had kids. The same system was the blueprint romney care used to enforce their insurance mandate.
I'd want to see international comparative data before I considered that a statistically significant cause. I'm not saying it isn't, but given the percentage of children born to never-married mothers these days, the change from marital to non-marital births may be your outcome, rather than an absolute decline in births.
It takes a lot of individual decisions to drop a whole population's birthrate. We've reached below replacement in the US despite the fact that, among my friends, six or more children is common and ten is unremarkable. We and all the other religious families (Protestant, Catholic, Jewish, Moslem) are not significantly affecting the nationwide number.