Pesticides

Pregnancy

MotherToBaby describes mixed human evidence. Thomas et al. (1992) followed 7,450 pregnancies during aerial malathion spraying and found no important association with spontaneous abortion, stillbirth, growth restriction, or most congenital anomaly categories. Gastrointestinal anomalies were associated with second-trimester exposure, but this result was based on 13 cases. Grether et al. (1987) studied live births, birth defects, and low birth weight; it did not study miscarriage, so MotherToBaby's statement that two studies found no miscarriage effect is not fully supported by those two studies. Furlong et al. (2025) linked Arizona pesticide-use records with 1,237,750 births and found that proximity within 500 meters to some pyrethroid, organophosphate, or carbamate applications before conception or in the first trimester was associated with stillbirth. The study used residence and agricultural-use records as exposure proxies, could not capture early miscarriages, and cannot establish cause. A 2024 cross-sectional survey in China reported associations between broadly self-reported periconceptional pesticide exposure and some birth defects, but only 339 women were classified as exposed and the exposure was not limited to one ingredient. Recent observational studies include low Apgar associations in Arizona (Yang et al., 2026), recalled pesticide spraying and later child development in Tanzania (Mwakalasya et al., 2025), and urinary pyrethroid markers with some three-year development scores in China (Zhang et al., 2026). These studies examine different chemicals, routes, populations, and outcomes; they do not justify treating all pesticides or food residues as one exposure or claim that exposure caused an outcome.

Breastfeeding

The live summary's claim that no studies have examined pesticide exposure during breastfeeding is too broad. CDC says some pesticides may pass into milk and that studies of infant effects are lacking. Kao et al. (2019) measured organochlorine pesticide residues in milk from 55 Taiwanese mother-infant pairs and examined infant development at 10 to 12 months. The authors reported associations for some chemicals but called the findings suggestive and recommended confirmation. They noted the small sample and did not account for breastfeeding amount or duration, so prenatal and postnatal exposure could not be separated. Mehta et al. (2020) tested milk from 75 mothers in Haryana, India; DDT and DDE were detected in a small fraction of samples, but the study did not test infant developmental outcomes. A 2026 Mexican study reported an association between breastfeeding for more than 12 months and higher serum p,p'-DDE among males and children 124 months or younger; it measured serum residues, not infant health effects. Overall human evidence about pesticide-specific infant effects through milk is sparse, and the evidence does not establish that breastfeeding caused developmental differences.

What was tested

Studies measured different things: proximity to recorded agricultural applications (Furlong 2025 and Yang 2026), maternal self-reports of pesticide activities (Liu 2024 and Mwakalasya 2025), urinary pesticide markers (Baba 2025 and Zhang 2026), and pesticide residues in breast milk (Kao 2019 and Mehta 2020). These measures do not capture the same dose or route and do not cover every pesticide. Most reported pregnancy and child outcomes came from observational research, so associations do not establish cause. Food-residue monitoring and occupational or household exposure studies answer different questions.