WWF plans to appeal against an Advertising Standards Authority (ASA) ruling on one of its awareness campaigns as "alarmist".
The print ad, which has now been withdrawn, featured an image of an unborn child, with the words, "The womb should be the safest place on earth.
But today our bodies are contaminated with over 300 man-made chemicals, to which our great-grandparents were never exposed".
Such an image could be unduly alarming to young mothers or those considering having a baby, according to the ASA. The ad was deemed to be misleading because it implied that all 300 chemicals could be found in one body rather than people in general. The ASA also criticised the ad for implying that all man-made chemicals may cause health problems.
However, the body agreed with WWF on a number of points made about toxic chemicals. The campaign was not misleading in implying that "pollutants had been linked to birth defects in children".
The ad appeared 19 times with a reach of 1.7 million people. Four members of the public, including one pregnant woman, complained to the ASA, with two other complaints from the chemical industry.