I think they would indeed have pressed on regardless.
However, those around them could have seen danger and given warnings which were then ignored.
By 1890 Alexandra had had an uncle, a brother and a nephew with the disease. Irene and Heinrich produced Waldemar (haemophiliac) nine months after their wedding, so fertile young couple conceiving during the honeymoon. There were then six years and eight months between Waldemar and Sigismund, which strongly suggests that they were trying to avoid having more children. Heinrich had six healthy nephews, so producing heirs was not an issue, however.
Remember, it was not enough to have sons. They needed healthy sons. Alexander III was a second son. Alexandra herself had been considered as a bride for Albert Victor, who died at 28, leaving his brother as heir. Both AV and Nixa had reached adulthood in apparently good health. And so on.....
A deadly disease which only occurred in boys, and kept cropping up in Alexandra's close family.......
Ann