Originally published on CNN by Jacqueline Howard.

Fruits and vegetables are an essential part of a healthy pregnancy diet, providing vitamins and fiber. Yet some might also come with pesticide residues.

Among women undergoing infertility treatment in the United States, consuming more fruits and vegetables with high amounts of pesticide residue was associated with a lower chance of pregnancy and a higher risk of pregnancy loss, according to a study published in the journal JAMA Internal Medicine on Monday.
Pesticides are pest-killing substances often applied to fruits and vegetables to help protect them — and us — against harmful mold, fungi, rodents, weeds, and insects. There has been growing concern that exposure to pesticides can be tied to certain acute and chronic human health concerns.
Steering clear of pesticides when buying veggies Steering clear of pesticides when buying veggies00:37
“Most Americans are exposed to pesticides daily by consuming conventionally grown fruits and vegetables,” said Dr. Yu-Han Chiu, a research fellow in the department of nutrition at the Harvard T.H. Chan School of Public Health and first author of the study.
“There have been concerns for some time that exposure to low doses of pesticides through diet, such as those that we observed in this study, may have adverse health effects, especially in susceptible populations such as pregnant women and their fetus, and on children,” she said. “Our study provides evidence that this concern is not unwarranted.”
Yet the findings should be digested with caution, said Janet Collins, executive vice president of science and regulatory affairs for CropLife International, a trade association representing the manufacturers of pesticides. Collins was not involved in the study.
“The JAMA research publication does not show a direct link between pesticide residue intake and pregnancy outcome, as the authors state. This is a hypothesis-generating study, and as the authors recommend, we agree that before a definitive outcome can be established the issues require further study,” she said in an emailed statement.

How harmful are pesticide residues?

The study involved 325 women between 18 and 45 who were undergoing infertility treatment with assisted reproductive technology at the Massachusetts General Hospital, the researchers said.
The women completed a diet assessment questionnaire and had their height, weight, and overall health measured, while the researchers accounted for confounding factors that could influence the study results, including their intake of supplements and residential history.
The researchers analyzed each woman’s pesticide exposure by determining whether the fruits and vegetables she consumed had high or low levels of pesticide residues, based on reports from the US Department of Agriculture’s Pesticide Data Program, which monitors the presence of pesticides in foods sold throughout the United States.
Some fruits and vegetables with a low amount of pesticide residue include avocados, onions, dried plums or prunes, corn and orange juice. Those with a high amount include fresh plums, peaches, strawberries, spinach and peppers.
The researchers found that, compared with women who ate less than one daily serving of high-pesticide-residue fruits and vegetables, those who ate 2.3 servings or more had 18% lower probability of getting pregnant and 26% lower probability of giving birth to a live baby.
Consuming fruits and vegetables with a high amount of pesticide residue was positively associated with the probability of losing a pregnancy, the researchers found.
However, consuming low-pesticide-residue fruits and vegetables in lieu of high-pesticide-residue foods was associated with higher odds of pregnancy and giving birth, the researchers found.
“Although we did find that intake of high-pesticide-residue fruits and vegetables were associated to lower reproductive success, intake of low-pesticide-residue fruits and vegetables had the opposite association,” Chiu said.
“A reasonable choice based on these findings is to consume low-pesticide-residue fruits and vegetables instead of high-pesticide-residue ones. Another option is to go organic for the fruits and vegetables known to contain high pesticide residues,” she said. “It is very important to keep in mind that, as far as we are aware, this is the first time that this association is reported, so it is extremely important that our findings are replicated in other studies.”
Which fruits you should buy organicWhich fruits you should buy organic 00:44
However, purchasing organic fruits and vegetables can be costly, said Irva Hertz-Picciotto, a professor, and director of the Environmental Health Sciences Center at the University of California, Davis, who was not involved in the study.
“This is more difficult for those already vulnerable due to their socioeconomic circumstances. Avoiding pesticides becomes an ‘environmental justice’ issue, making it all the more important to reduce use of pesticides throughout agriculture and adopt more sustainable and health-promoting methods for food production,” Hertz-Picciotto said.
She added that the new study was “very well-executed, thoughtful and thorough” and that although replicating the study would be desirable, the findings provide strong evidence that certain pesticides are associated with reproductive concerns.
“The limitation of this study is that the participants were seeking fertility treatments, and hence the results pertain specifically to reproductive potential in a certain subset of women,” she said.