I am at the moment reading a biography of Catherine de Medici by Leonie Frieda.
Catherine was –by the rules of the time- a commoner when she married Henry 11 of France, this even though she came from the immensely powerful Medici family of Florence.
To consolidate her position it was imperative that she conceive as soon as possible, unfortunately this was not to be the case.
Even though Henry did his duty royally, and already had fathered several children, Catherine failed to become pregnant.
In desperation she tried everything, drinking foul concoctions of mules urine and even boring a hole in the floor to spy on Henry and Diane de Poitiers- his mistress- to discover what they were doing better than her that made conception possible.
Eventually she called in the help of a sensible doctor called Jean Fernel.
He found that their reproductive organs both carried” slight abnormalities” and suggested a way these might be overcome.
Catherine more or less immediately became pregnant and then went on to bear ten children for Henry.

The mind can only boggle to imagine what these “abnormalities” were and how they were overcome. Frustratingly history doesn’t tell us and we can only speculate