When trying to conceive it is not enough to stop smoking, avoid alcohol and be careful not to eat raw foods if contaminated and not sufficiently treated. A new study conducted by Harvard University in Boston (USA) and promoted by the ‘National Institute of Environmental Health Sciences (NIEHS)’, for the first time demonstrated that eating fruit and vegetables even with low residual doses of pesticides means that women undergoing infertility treatments are less likely to succeed [1].
The results of the US search
Yu-Han Chiu and his collaborators, in a study published in Jama, presented the results of the prospective study conducted on 325 women who completed a questionnaire on eating habits and were then subjected to 541 cycles of in vitro fertilization in the period 2007-2016 ART at the Massachusetts General Hospital Fertility Center in Boston (USA).
The hospital’s research team demonstrated an association between eating fruit and vegetables even with low residual levels of pesticides and lower chances of a successful pregnancy.
This group of women who had completed a dietary questionnaire before undergoing treatments and who were less exposed to pesticides were also less exposed to the risk of spontaneous termination of pregnancy than those who had been exposed to higher levels of pesticide chemicals.
Women who used to eat fruit and vegetables with more pesticides were 18% less likely to become pregnant and 26% less likely to maintain a pregnancy.
Risk factors for those wishing to become pregnant
The study examines infertile patients undergoing in vitro fertilization cycles and these conclusions are not generalizable to women who conceive spontaneously, although numerous experimental studies have demonstrated [2] a close relationship between life in rural areas with high pollution rates and pregnancy outcomes.
It is therefore good for those seeking pregnancy to bear in mind the factors that could more easily jeopardize or make it difficult to start a pregnancy, starting with the diet.
“Pesticides are powerful molecules specifically designed to kill living organisms,” said Professor Paolo Emanuele Levi Setti, director of the department of gynecological surgery at Humanitas. These include insecticides, rodenticides, fungicides, and herbicides. More than 600 chemical pesticides and thousands of commercial formulations are currently on the market, and out of these 450 million kg are applied annually in the United States, out of which 75% in agriculture [3]. The study published in JAMA [1] on the association between exposure to pesticides and decreased female fertility is an elegant example of a prospective epidemiological study using sophisticated biological markers to identify the effect of pesticide exposure on human health. In this study, the authors found that regular consumption of conventionally grown fruits and vegetables treated with pesticides is associated with increased risk of pregnancy loss, while consumption of organic fruits and vegetables significantly reduce the risk of pregnancy loss and increase fertility. All pesticide levels were within the exposure levels considered normal for the American population.
What are the implications of this study? It comes at a time when more lines of research suggest that human fertility is declining and that the frequency of damage to the reproductive system is increasing. Sperm count in Western countries has decreased by 54% since 1973, the incidence of malformations in male genitalia has doubled and testicular cancer has increased by 55% in the United States since 1970 [4]. These changes are too rapid to be of genetic origin. Environmental exposures are therefore almost certainly involved. To be precise, this study does not claim that the pesticides actually caused an increase in abortions or that a class of pesticides is responsible for the decrease in female fertility.
The observations made in this study give us a warning that our current laissez-faire attitude towards the regulation of pesticides is inappropriate. We can no longer allow ourselves to assume that a spermicide is harmless until it has been definitively proven to cause harm to human health.
How should doctors respond to these results? The answer is to educate. Educate our patients about the dangers hidden in the modern environment and stimulate a reduction of exposure where possible [3]. Living in our cities is certainly not healthy, but sometimes the countryside can be worse [5]”.
- Chiu YH, Williams PL, Gillman MW, Gaskins AJ, Mínguez-Alarcón L, Souter I, et al. Association Between Pesticide Residue Intake From Consumption of Fruits and Vegetables and Pregnancy Outcomes Among Women Undergoing Infertility Treatment With Assisted Reproductive Technology. JAMA Intern Med. 2018;178(1):17-26. doi: 10.1001/jamainternmed.2017.5038. PubMed PMID: 29084307; PubMed Central PMCID: PMCPMC5814112.
- Savitz DA, Whelan EA, Kleckner RC. Self-reported exposure to pesticides and radiation related to pregnancy outcome–results from National Natality and Fetal Mortality Surveys. Public Health Rep. 1989;104(5):473-7. PubMed PMID: 2508175; PubMed Central PMCID: PMCPMC1579951.
- Landrigan PJ. Pesticides and Human Reproduction. JAMA Intern Med. 2018;178(1):26-7. doi: 10.1001/jamainternmed.2017.5092. PubMed PMID: 29084335.
- Levine H, Jørgensen N, Martino-Andrade A, Mendiola J, Weksler-Derri D, Mindlis I, et al. Temporal trends in sperm count: a systematic review and meta-regression analysis. Hum Reprod Update. 2017;23(6):646-59. doi: 10.1093/humupd/dmx022. PubMed PMID: 28981654.
- ACOG. Exposure to toxic environmental agents. Obstet Gynecol. 2013;122(4):931-5. doi: 10.1097/01.AOG.0000435416.21944.54. PubMed PMID: 24084567.
