Pregnant women who are exposed to coal smoke and pesticides are up to four times more likely to have babies with neural tube defects (NTDs), a Chinese study has found.
The researchers studied 80 newborn babies and aborted foetuses with brain and spinal cord defects and found that their placentas had significantly higher amounts of certain chemicals, compared to placentas of babies without such birth defects.
Birth defects have long been linked to folic acid deficiency, maternal obesity and diabetes. Environmental pollution has also been suspected as a culprit, but there has been very little direct evidence showing the link.
In the Chinese study, researchers detected high levels of polycyclic aromatic hydrocarbons (PAHs) that come from inhaling smoke from burning coal, and synthetic pesticides such as DDT, hexachlorocyclohexane (HCH) and endosulfan in the placentas of babies with NTDs.
Pollution can affect unborn babies
"In addition to nutrients and oxygen, pollutants can readily cross the preplacental structures and potentially impact embryonic development," lead author Tong Zhu at the State Key Joint Laboratory for Environmental Simulation and Pollution Control in Beijing University said.
The study's findings were published in the Proceedings of the National Academy of Sciences.
Zhu and colleagues recruited pregnant women in four rural counties in northern Shanxi province, where NTDs occur in 14 out of every 1,000 babies – far higher than the national average.
They analysed the placentas of 80 babies or aborted foetuses with NTDs and compared them to placentas of 50 babies without such defects.
Women whose placentas had higher than average levels of the PAH chemicals from burning coal were 4.5 times more likely to have babies with defects, while those with more than average levels of pesticides were around three times more likely to have babies with defects, the researchers found.
Zhu urged women to avoid coal smoke and to use cleaner fuels for heating and cooking, as well as to avoid inhaling second hand smoke.
(Reuters Health, Tan Ee Lyn, July 2011)