Penny Rohleder, from New South Wales, Australia, shared the family portrait with mum blogger Constance Hall on Facebook on 25 July.
“I don’t know whether to be proud or embarrassed that my five-year-old son knows this,” she wrote.
“Julian drew a family portrait. I said: ‘What’s that red bit on me?’ and he replied, real casual: ‘That’s your period’.”
Giving background to the family portrait, Rohleder explained that she became ill with pulmonary embolism in October 2016. This meant she was put on blood thinning treatment.
It caused her periods to become “very bad”.
“Jules was super concerned,” she told Daily Mail Australia.
“But he knows about periods - kids follow you to the toilet every chance they get - and so he just kept asking me if I was ok.”