I think the Covid vax did more to lower birth rates than Covid itself.
Depopulation of Greece - Greek Historian Polybius
As I blame those who assign fortune and destiny as the Limits to the belief of the direct interference of Providence in human affairs moving causes in common events and catastrophes, I wish now to enter as minutely on the discussion of this subject as the nature of an historical work will admit. Those things of which it is impossible or difficult for a mere man to ascertain the causes, such as a continuous fall of rains and unseasonable wet, or, on the contrary, droughts and frosts, one may reasonably impute to God and Fortune, in default of any other explanation; and from them come destruction of fruits, as well as long-continued epidemics, and other similar things, of which it is not easy to find the cause. On such matters then, we, in default of a better, follow the prevailing opinions of the multitude, attempting by supplications and sacrifices to appease the wrath of heaven, and sending to ask the gods by what words or actions on our part a change for the better may be brought about, and a respite be obtained for the evils which are afflicting us. But those things, of which it is possible to find the origin and cause of their occurrence, I do not think we should refer to the gods. I mean such a thing as the following. In our time all Greece was visited by a dearth of children and generally a decay of population, owing to which the cities were denuded of inhabitants, and a failure of productiveness resulted, though there were no long-continued wars or serious pestilences among us. If, then, any one had advised our sending to ask the gods in regard to this, what we were to do or say in order to become more numerous and better fill our cities,—would he not have seemed a futile person, when the cause was manifest and the cure in our own hands? For this evil grew upon us rapidly, and without attracting attention, by our men becoming perverted to a passion for show and money and the pleasures of an idle life, and accordingly either not marrying at all, or, if they did marry, refusing to rear the children that were born, or at most one or two out of a great number, for the sake of leaving them well off or bringing them up in extravagant luxury. For when there are only one or two sons, it is evident that, if war or pestilence carries off one, the houses must be left heirless: and, like swarms of bees, little by little the cities become sparsely inhabited and weak. On this subject there is no need to ask the gods how we are to be relieved from such a curse: for any one in the world will tell you that it is by the men themselves if possible changing their objects of ambition; or, if that cannot be done, by passing laws for the preservation of infants. On this subject there is no need of seers or prodigies. And the same holds good of all similar things. But in regard to events of which the causes are impossible or difficult to discover, it is reasonable to feel a difficulty. And in this class may be reckoned the course of Macedonian history. For the Macedonians had enjoyed many important favours at the hands of the Romans, having been as a nation liberated from arbitrary government and imports, and having obtained undisputed freedom in the place of slavery; and having been individually relieved to a great extent from intestine factions and civil bloodshed.