Lower IVF success rates have been linked to flame retardants commonly found in household items.
The findings come from the first study to look for an association between organophosphate flame retardants (PFRs) and reproductive outcomes in women.
'This carefully conducted study analysed chemicals from flame retardants in urine from women having IVF and found that the chemicals were detected in most,' said Professor Richard Anderson of the University of Edinburgh, who was not involved in the study. 'Worryingly, higher concentrations of these chemicals were associated with substantial reductions in the success of IVF, with a lower chance of having a baby.'
PFRs are considered a safer alternative to past flame retardants, which studies had linked to negative health and epidemiologic effects, and can be found in furniture, gym mats and household products. However, studies show they can migrate into the air and dust of indoor environments, and disrupt hormones and embryo development in animals.
In this most recent study, a team of researchers at the Harvard T.H. Chan School of Public Health in Boston, Massachusetts analysed urine samples from 211 women who were undergoing IVF and were enrolled in the Environment and Reproductive Health (EARTH) study, which took place from 2005 to 2015.
They looked for five urinary PFR metabolites (products of a chemical that has been metabolised), and found three were present in over 80 percent of women. Success rates for measured IVF outcomes significantly declined for women with the highest urinary levels of PFR metabolites, compared to those with the lowest levels. On average, this included a 10 percent decrease in successful fertilisation, a 31 percent decrease in implantation, a 41 percent decrease in clinical pregnancy, and a 38 percent decrease in live births.
'These findings suggest that exposure to PFRs may be one of many risk factors for lower reproductive success,' said first author Dr Courtney Carignan of Michigan State University. 'They also add to the body of evidence indicating a need to reduce the use of these flame retardants and identify safer alternatives.'
Professor Allan Pacey of the University of Sheffield cautioned that the study does not prove there is a link between PFRs and lower fertility, as 'it only describes an association' and pointed out that: 'it is not clear if this effect would be seen in couples who are not undergoing IVF'. Saying that fire safety was still important, he suggested 'before men and women undergoing IVF throw away their yoga mats, I think we need a bit more data in larger populations and in various parts of the world'.
The researchers say further research is also needed to investigate the potential impact of PFRs on male partners.
The study was published in Environmental Health Perspectives.