We are delighted by the response our editorial regarding labor augmentation/induction and autism has elicited. Rosenstein et al claim that in our editorial we misinterpreted the results of Table 3 of the paper by Gregory et al. Their assumption is incorrect. Our interpretation is exactly the same as theirs; however, our conclusion is different. The associations between each birth year and subsequent autism spectrum disorder diagnosis in comparison to 1990 (reference year) became nonsignificant during each of the 3 most recent birth years of the study (1996 through 1998). As stated in our editorial this was an abrupt change and in our view this abrupt change provides strong evidence that indeed the wrong diagnostic criteria for autism spectrum disorder had been applied in the first 6 birth years of the study (1990 through 1995). In fact, a reanalysis of the study restricted to years 1996 through 1998 by Gregory et al, as we have previously pointed out, showed no associations between exposure to labor and increased odds of autism–a conclusion that affirmed our assertion.

Rosenstein and colleagues claim that diagnostic misclassification can lead to false estimates of an association, only if it is differential, and that the estimated association between labor induction/augmentation and autism adjusted out the potential influence of any yearly trend in autism diagnosis in Table 3 of the Gregory et al article. However, even nondifferential misclassification can also bias an association. In addition, we never questioned whether Gregory et al did or did not adjust for birth year. Our claim was that their data regarding autism were based on an incorrect diagnosis for the birth years 1990 through 1995.

As previously stated we believe that the authors of the original article should consider retracting their initial conclusion regarding an association between induction or augmentation of labor and autism risk because the diagnosis of autism was wrong during most of the study years and therefore the association was not proven to exist in the first place.

To the interested reader, we have already provided a detailed point-by-point critique of the Gregory et al study.