Pregnant women are being advised to avoid chemicals in household products such as food packaging, cosmetics and family medicines that could cause harm to their unborn babies.

In a paper co-authored by two Scottish universities, the Royal College of Obstetricians and Gynaecologists (RCOG) says women should be made aware of the sources of chemicals to minimise the possibility of harm during pregnancy, and urges them to "play it safe", despite uncertainty about chemicals' effects.

However, the advice has provoked concern, with critics saying the report is alarmist.

In its Scientific Impact Paper the RCOG says there is no official antenatal advice for women who are pregnant or breastfeeding about the potential risks exposure to some chemicals could pose.

The report's authors acknowledge that while there is little evidence to suggest whether such chemicals do affect a baby's development, or even if there is a risk to health, they advise women to assume that a risk is present.

Women can be exposed to chemicals at low levels, through food packaging, household products, over-the-counter medicines and cosmetics, the report says. It advises women to take care handling products such as moisturisers, sunscreens and shower gels, as regulations do not require manufacturers to name all potentially harmful chemicals, when used in low dose, on the label.

It recommends pregnant women use fresh food whenever possible by reducing foods in cans/plastic containers, minimise the use of personal care products, avoid paint fumes and pesticides, and only take over-the-counter medicines when necessary. Dr Michelle Bellingham, of the Institute of Biodiversity, Animal Health and Comparative Medicine, Glasgow University, co-author of the paper, said: "While there is no official advice on this topic available, there is much conflicting anecdotal evidence about environmental chemicals and their potentially adverse effects on developing babies.

"The information in this report is aimed at addressing this problem and should be conveyed routinely in infertility and antenatal clinics so women are made aware of key facts that will allow them to make informed choices regarding lifestyle changes."

Professor Richard Sharpe, of the Medical Research Council (MRC) Centre for Reproductive Health at Edinburgh University, said: "For most environmental chemicals we do not know whether or not they really affect a baby's development, and obtaining definitive guidance will take many years.

"This paper outlines a practical approach that pregnant women can take if they are concerned about this issue and wish to 'play safe' in order to minimise their baby's exposure. However, we emphasise that most women are exposed to low doses of chemicals over their lifetime which in pregnancy may pose minimal risk to the developing baby."

Professor Scott Nelson, chairman of the RCOG Scientific Advisory Committee, said chemicals have the potential to interfere with hormone systems, which play key roles in foetal development.

He said: "While pregnant women should be aware of potential risks, there is still considerable uncertainty about the extent of the exposure effects and any women with concerns about certain chemical exposures should consult their obstetrician or midwife."

But Tracey Brown, from Sense About Science, said the warning could cause more harm than good.

She said: "People spend a lot of time and money trying to work out which advice to follow, and which products to buy or avoid. The simple question parents want answered during pregnancy is, 'Should we be worried?'.

"What we need is help in navigating these debates about chemicals and pregnancy. Dis-appointingly, the RCOG report has ducked this. There are many unfounded rumours about links between particular substances and pregnancy outcomes.

"By contrast, we have plenty of evidence that stress is a major risk factor in pregnancy. Researchers and professional bodies should not be adding to it."