The document discusses the perinatal period, which begins at 22 weeks of gestation and ends 7 days after birth. It defines perinatal mortality as stillbirths and deaths within the first week of life. The antepartum period refers to the period between 24-26 weeks of gestation until birth. The document also provides ICD-10-CM coding guidelines for conditions occurring during the perinatal period, including codes for stillbirths, live births, and conditions affecting newborns related to length of gestation, birth trauma, infections, and other disorders originating in the perinatal period.