Women who ate more fruits and vegetables containing high amounts of pesticide residue were less likely to get pregnant or have a live birth following infertility treatments, an observational study found.

Compared with women who ate less than one serving per day of high-pesticide residue fruits and vegetables, those who ate two to six daily servings had an 18% lower probability of clinical pregnancy (95% CI 5%-30%, P=0.04 ) and a 26% lower probability of live birth (95% CI 13%-37%, P=0.02), said Jorge Chavarro, MD, of the Harvard T.H. Chan School of Public Health in Boston, and colleagues.

The probability of pregnancy loss increased with each quartile of high-pesticide fruit and vegetable consumption. The probability was 7% for the first (lowest) quartile, 23% for the second, 24% for the third, and 34% for the highest quartile (P=0.04 for trend), Chavarro's group reported online in JAMA Internal Medicine.

Consuming one serving per day of low-pesticide residue fruits or vegetables in lieu of one high-pesticide serving was associated with 79% higher odds of clinical pregnancy (95% CI 11%-188%) and 88% higher odds of live birth (95% CI 16%-205% ), the authors estimated.

"These data suggest that dietary pesticide exposure within the range of typical human exposure may be associated with adverse reproductive consequences," Chavarro's group stated, adding that "there has been a growing concern that permitted levels of pesticide residues in food defined by traditional toxicological testing may be too high, especially for susceptible populations such as pregnant women or infants."

Fruits and vegetables are an important part of a healthy diet, but they also serve as the primary vehicle for pesticide residue exposure in the general population. Previous studies have shown that many pesticides used in agriculture have harmful effects on reproductive health outcomes, including decreased fertility, spontaneous abortion, stillbirth, and developmental abnormalities, the authors said.

In an accompanying editorial, Philip Landrigan, MD, of the Icahn School of Medicine at Mount Sinai in New York City, said, "The observations made in this study send a warning that our current laissez-faire attitude toward the regulation of pesticides is failing us. We can no longer afford to assume that new pesticides are harmless until they are definitively proven to cause injury to human health."

"We need to overcome the strident objections of the pesticide manufacturing industry, recognize the hidden costs of deregulation, and strengthen requirements for both premarket testing of new pesticides, as well as post marketing surveillance of exposed populations -- exactly as we do for another class of potent, biologically active molecules -- drugs," Landrigan said.

"How should physicians respond to these findings? The answer is to educate," Landrigan advised. "Educate our patients about the hidden dangers of pesticides in the modern environment and urge reductions in exposure wherever possible. Encourage our patients to eat organic."

Fruits and vegetables containing high amounts of pesticide residue identified in the study included strawberries, spinach, green peppers, peaches, plums, potatoes, grapes, string beans, apples, and pears. Low-pesticide produce included peas, lima beans, onions, beans, lentils, avocados, corn, and cabbage.

The study included 325 women who completed a dietary questionnaire and subsequently underwent cycles of assisted reproductive technologies as part of the Environment and Reproductive Health (EARTH) study at a fertility center in Boston. The authors determined participants' intake of high-pesticide and low-pesticide fruits and vegetables using data from the U.S. Department of Agriculture's Pesticide Data Program.

During the 2006-2015 study period, participants consumed 1.7 mean daily servings of high-pesticide and 2.8 mean daily servings of low-pesticide produce. There were 228 live births (42% of participants). Key outcomes included successful implantation, clinical pregnancy, live birth, and pregnancy loss. Chavarro's group adjusted for potential confounders including age, body weight, smoking status, race, organic fruit and vegetable consumption, folate intake, and the type of infertility diagnosis (male factor versus female factor versus unknown.)

There was not a significant association between pesticide consumption and successful implantation (P=0.08), the study found.

Study limitations included the fact that pesticides exposure was not directly measured, but estimated from self-reported dietary intake paired with pesticide residue surveillance data. In addition, "Although we have adjusted for organic fruit and vegetable intake, data on whether individual fruits or vegetables were consumed as organic or conventional were not collected, possibly leading to exposure misclassification," they said.

"Because, to our knowledge, this is the first report of this relationship in humans, confirmation of these findings is warranted," they concluded.