https://www.statista.com/statistics/332502/fertility-rate-in...
https://data.worldbank.org/indicator/SP.DYN.TFRT.IN?page=&lo...
I suspect that a couple years is not enough to draw any conclusions.
Second: even if this were true, it would still be a net win. Babies now are better than babies 3 years from now.
Also, women have a limited number of fertility years. This would give them the chance to have more.