We thank Drs Yarborough and Erdreich for their interest in our study, as well as in our previous studies.
In their criticism, they reiterate limitations we explicitly acknowledge in the article, including sample size, lack of dose response, multiple chemicals, and potential selection bias, to mention a few. Yet, to our knowledge, this is the first prospective controlled study to have done such analysis, controlling for maternal socioeconomic class, IQ, education, and family income. Naturally, there will never be a randomized trial in this area, to the extent possible, and any observational study has the risk of uncontrolled, unknown confounders. We believe our study controlled for confounders of neurodevelopment by measuring maternal IQ, education, and family income.
Koren G. Child Neurocognitive and Behavioral Outcomes and Maternal Solvent Exposure During Pregnancy—Reply. Arch Pediatr Adolesc Med. 2005;159(7):690-692. doi:10.1001/archpedi.159.7.690-b