Author response to "Pitfalls of analyzing perinatal outcomes by health care provider".

We appreciate and have carefully considered Dr. Jain's response.[1] We opted to reduce (not eliminate) bias caused by the unequal distribution of medical risk factors by type of most responsible provider (MRP) using a validated weighted risk score to group birthers into prenatal risk groups. We appreciate the etiological consideration Dr. Jain suggested and can also think of factors that might predispose midwifery clients to worse outcomes. With respect to MRP assignment, MRP is a mandatory data field, is clearly defined in our paper and, in our view, is the best variable to use when describing outcomes of midwife-led care. [Extracted from the article]