Sharon Sawyer, from Worthing, shared a photo on Facebook of the toilet sign that showed a woman in a pink dress with a child next to her.
The male toilet sign, shown in a picture in the comments, simply had a man.
Sawyer added: “The picture below shows a woman and child. The picture in the comments just shows a man, why?
“This is in your Holmbush store at Shoreham. Please could you explain why this happened in your recent revamp and what plans you have to ensure that if you continue with these signs, that both signs reflect or just have no pictures of children in for the future?”
People commented on Sawyer’s post in agreement, with one writing: “Well said Sharon. Families are made up differently and children are cared for by both sexes.”
At the time, the retailer replied to Sawyer’s Facebook post: “Hi Sharon, thanks for your comments and I’ve shared them with our Development team for future review. Kind regards, Donna.”
A spokesperson for M&S told HuffPost UK: “Our baby changing facilities are in a unisex area and we also provide a baby changing mat in both the male and female toilet facilities.”
The spokesperson said they will be adding a child to the male toilet sign.