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29-11-2011 | Gynaecology | Article

Exposure to phthalates at conception may increase risk for pregnancy loss


Free abstract

MedWire News: High exposure to phthalates around the time of conception can significantly increase a woman's risk for losing the pregnancy, report researchers.

"Rodent studies indicate that exposure to specific phthalates may induce female reproductive toxicity," explain Gunnar Toft (Aarhus University Hospital, Denmark) and colleagues.

They therefore carried out a small exploratory study to assess whether exposure to phthalates around the time of conception influenced risk for pregnancy loss in 128 Danish women.

In total, four primary and two oxidized secondary phthalate metabolites were tested in urine samples taken from the women on day 10 after the first day of menstruation of the last menstrual period before conception occurred. Urine samples taken during the previous menstrual cycle were also available for 111 women and were tested for the same metabolites.

Subclinical embryo loss was diagnosed through multiple measurements of human chorionic gonadotropin and clinical spontaneous abortions were self-reported by the women during telephone interviews.

In total, 48 women lost their pregnancies. As reported in the journal Environmental Health Perspectives, Toft and team found that women exposed to the highest levels of monoethylhexyl phthalate (MEHP; mean urine level 23.4 ng/ml) were a significant 2.9-fold more likely to have a spontaneous abortion than those exposed to the lowest amounts (mean urine level 16.2 ng/ml).

Risk for subclinical embryo loss (n=32) was even higher for these women, with those in the highest MEHP exposure tertile having a significant 40.7-fold increased risk compared with women in the lowest tertile.

No significant links between pregnancy loss and phthalate exposure at conception were observed for the other metabolites tested, note the investigators.

"Since low estradiol and progesterone levels have been associated with human fetal loss, the association between MEHP and pregnancy loss in our study population might reflect a phthalate-induced decrease in the secretion of these hormones," suggest Toft and co-workers.

"To our knowledge, this is the first study to show an association between phthalate exposure and pregnancy loss," they write.

The results are concerning, as phthalates are used widely in industry to increase the flexibility of plastics and can be released into food during processing. It can therefore be difficult to judge the amounts of these chemicals in different foods.

However, due to the relatively small size of the study, "the findings need to be repeated in larger cohorts before final conclusions on the adverse effects of MEHP on pregnancy loss can be made," conclude Toft et al.

By Helen Albert

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