How, though? It's not like we've had the ability to diagnose the majority of these diseases in utero until fairly recently, nor have we the means to intervene, even now. CRISPR as a tool has existed for just over a decade, and we're still very far from the ability to reliably modify fetuses, even in lab animals, and it's been only possible for, what, 5 years now? Lab research did not stop after WW2, and even then we've barely gotten to this point. The ability to sequence the whole genome and find mutations for the major disorders is still a far off goal. The majority of disorders are now known to be polygenic, affected by hundreds of different gene variants, with each population group seemly affected by different groups of genes. Nor have we settled on a definitive group of gene variants that can reliably be identified to be deterministic of any widely distributed disorder, outside a small handful like CF and DMD.