Female exposure to pesticides during pregnancy may affect sleep patterns in female offspring

Women's exposure to pesticides during pregnancy may lead to differences in the amount and timing of sleep in their female offspring during puberty, according to a new University of Michigan study published in Environmental Research

"While non-occupational exposure to pesticides is widely believed to occur through chemical products used in the home to deworm, exposure to pesticides can also occur through other routes, such as diet

While other studies have looked at the effects of other chemicals on sleep, including lead, little is known about the effects of pesticides on sleep in offspring, she said

"Melatonin is important for sleep, so we wondered if melatonin during pregnancy was related to sleep," Zamora said

To understand how environmental exposures affect pregnant women and children, the researchers used data from the Mexico Early Life Exposure and Environmental Toxins cohort, which followed women in Mexico City for 20 years

They tested the two pesticides in urine samples from 137 women, collected during their last trimester of pregnancy, and then conducted a sleep study of the women's adolescent offspring

Zamora and his colleagues found that maternal in utero exposure to chlorpyrifos, but not pyrethroids, was associated with longer sleep duration and later sleep midpoint (a marker of sleep duration) in adolescent offspring -- but only in girls

While we generally consider extended sleep duration to be desirable, it is important to determine the reasons for prolonged sleep duration in follow-up studies

"Overall, these results are of public health importance given the continued widespread agricultural and possibly residential use of pyrethroids and chlorpyrifos in Mexico," Zamora said

To better understand the link, and the underlying mechanisms explaining gender differences, studies with larger samples and assessments of unregulated pesticides are needed, she said