This change in the method for determining when prenatal care began has resulted in a significant shift toward a later start of prenatal care. The statistical shift may not reflect an actual change in practice. The categories used for reporting the method of delivery of live births include vaginal, cesarean and other. Attendant at birth is categorized as physician, midwife or other. Physician includes medical doctors and doctors of osteopathy.
Midwife includes certified nurse midwives and midwives.
The number of out of wedlock live births is imputed. Prior to 1977, the marital status was inferred by examining statistical information on the certificate of live birth. In 1977, the procedure was modified to also identify out of wedlock live births when a paternity affidavit was filed, births that were previously identified as being in wedlock. This modification resulted in a noticeable increase in the estimated number of out of wedlock live births. Historically, several revisions of the ICD have been used, therefore, it is necessary to employ a comparability ratio when comparing cause of death statistics across revisions.