"By eight months, the foetus spends an estimated 25 per cent of its daily protein intake on manufacturing these hormonal messages to its mother" That's a lot of energy. Further, human mothers have a high chance of death from natural childbirth compared to most mammals.
Further the energy costs, pain, and suffering from monthy periods has a lot to do with the conflict, wolves for example don't suffer nearly as much.
Realistically it's at best a local optima, but robustness and adaptability are hindered but such inefficiency.