Doctors in the Iraqi city of Fallujah are reporting a high level of birth defects, with some blaming weapons used by the US after the Iraq invasion.
The city witnessed fierce fighting in 2004 as US forces carried out a major offensive against insurgents.
Now, the level of heart defects among newborn babies is said to be 13 times higher than in Europe.
The US military says it is not aware of any official reports showing an increase in birth defects in the area.
BBC world affairs editor John Simpson visited a new, US-funded hospital in Fallujah where paediatrician Samira al-Ani told him that she was seeing as many as two or three cases a day, mainly cardiac defects.
Our correspondent also saw children in the city who were suffering from paralysis or brain damage - and a photograph of one baby who was born with three heads.
He adds that he heard many times that officials in Fallujah had warned women that they should not have children.
Doctors and parents believe the problem is the highly sophisticated weapons the US troops used in Fallujah six years ago.
British-based Iraqi researcher Malik Hamdan told the BBC's World Today programme that doctors in Fallujah were witnessing a "massive unprecedented number" of heart defects, and an increase in the number of nervous system defects.