Incorrect Cervical Length Category Definitions

In the Original Investigation entitled “Effect of Cervical Pessary on Spontaneous Preterm Birth in Women With Singleton Pregnancies and Short Cervical Length: A Randomized Clinical Trial” published in the December 19, 2017, issue of JAMA,¹ cervical length categories were incorrectly defined on page 2318, in the Randomization and Masking subsection of the Methods. The correct categories are <20 mm and ≥20 mm-≤25 mm. This article was corrected online.