File photo: Chemicals found in couches, car seats and even yoga mats may be making it harder for women to become pregnant. Picture: Reuters

London - Chemicals found in couches, car seats and even yoga mats may be making it harder for women to become pregnant.

Flame retardants used in furniture escape into the air as household dust.

A study of women undergoing IVF found those who had breathed in the highest levels of these chemicals were nearly a third less likely to get pregnant.

It is believed the flame retardants, often used in foam stuffing, disrupt hormones that are important for fertility. Previous studies suggest they also make men’s sperm swim slower.

Researchers at Harvard T.H. Chan School of Public Health are the first to measure the chemicals in women’s urine. The results, from 211 women having IVF treatment, prompted the authors to warn couples to avoid products containing the chemicals, called organophosphate flame retardants (PFRs).

Lead author Dr Courtney Carignan said: "These findings suggest that exposure to PFRs may be one of many risk factors for lower reproductive success.

"They also add to the body of evidence indicating a need to reduce the use of these flame retardants and identify safer alternatives."

Everyday chemicals believed to cause infertility include phthalates, which are found in PVC flooring and shower curtains, and quaternary ammonium compounds, or "quats", found in disinfectants and mouthwash.

Of the women studied, those with the highest concentrations of PFRs were 31 percent less likely to get pregnant. It is thought that PFRs disrupt thyroid and sex hormones, which are both vital for couples starting a family. Richard Anderson, professor of clinical reproductive science at the University of Edinburgh, said: "While this study doesn’t prove that these chemicals are the cause of the lower success rate, it provides a firm basis for further experiments to investigate them. It also provides strong support for the need to regulate our exposure to chemicals and test their potential impact on fertility."