For some women, breastfeeding can make them feel sick, irritable or uncomfortable every time they start to release milk. The condition, called the Dysphoric Milk Ejection Reflex (D-MER), is not widely known, but experts say it is not uncommon and mothers shouldn't worry.

Some women with such symptoms feel they are “unfit as a mother” and blame themselves, but it is a physiological phenomenon that is different from postnatal depression or anxiety disorders, experts say.

One housewife in the city of Higashihiroshima began to notice that she felt depressed whenever she started breastfeeding her 5-month-old daughter. The mother, in her 40s, wondered if she had become mentally unstable after childbirth. Gradually she developed feelings of rejections to breastfeeding — even if she wanted to feed her child.