Quick weight loss after pregnancy, more than half a kilo a week, can affect the mother's milk negative.
A half-kilo weight loss per week is a moderate pace for breastfeeding women who are about to do away with their pregnancy weight.
It shows a Swedish study which examined the environmental pollution in the milk of some 30 women.
Samples of including the industrial chemical PCBs were about 10 and 20 weeks postpartum.
"Breastfeeding women are usually advised not to lose the weight quickly, but there are few other studies that actually looked at how much the levels of organic pollutants in human milk increases with weight loss," says Hilde Brekke, researcher at the Sahlgrenska Academy, in a press release.
The first few weeks of rapid weight loss due to fluid loss is not believed to affect the milk.