Pregnant women should be given more advice about the dangers of certain chemicals found in the environment and everyday foods and products, such as plastic, US doctors have said.

According to Dr Jeanne Conry, a consultant obstetrician and gynaecologist at Kaiser Permanente in California, when it comes to highlighting health issues to mothers-to-be, at the moment, ‘obesity trumps almost everything'.

"We put our time and energy there and don't dwell on some of the other things we should be aware of," she explained.

A recent survey of 2,600 obstetricians and gynaecologists in the US found that the majority do not speak to their pregnant patients about the potential dangers of some chemicals. In fact, at least half said they do not issue warnings about mercury, while most do not discuss other dangers such as air pollution, lead and chemicals in plastics.

However, most do discuss health issues such as smoking, drinking alcohol and diet.

Meanwhile, according to a testing programme by the US Centers for Disease Control and Prevention, chemicals commonly found in pregnant women's bodies include mercury, lead, flame retardants, pesticides, bisphenol A (used to make plastic products and phthalates (found in many cosmetic products). All of these have the potential to harm a foetus.

In fact, research indicates that even low levels of some of these chemicals may disrupt the development of certain organs such as the brain, or lead to birth defects or health problems later in life.

However, the doctors noted that this is a complex area and women can be confused by the messages they receive. For example, women are advised to avoid fish high in mercury, such as swordfish. However, these warnings could be misunderstood and women could end up avoiding fish altogether.

"Warnings over mercury could result in women eating less fish, which is a low-calorie protein rich in omega-3 fatty acids critical for a baby's brain development. This is a tricky one. Fish is such a good protein source for women, and they're probably not eating enough of it," commented Dr Naomi Stotland, lead investigator on the survey of obstetricians.

However, the doctors acknowledged that many women have no choice but to continue to be exposed to certain chemicals, for example, in the workplace.

They made their comments in Environmental Health News, published by Environmental Health Sciences.