2.1. Research Subjects and Grouping

The subjects were selected from 132 premature infants in the hospital from April 2018 to April 2020. According to the pathological examination of placenta, 81 cases with chorioamnionitis were taken as the experimental group and 51 cases without chorioamnionitis were taken as the control group. The incidence of cranial nerve injury in different groups of premature infants was analyzed by MRI diagnosis based on the principal component analysis (PCA) artificial intelligence algorithm, so as to analyze the correlation between cranial nerve injury and placental inflammation in premature infants. Placental inflammation was divided into stage 0, stage I, stage II, and stage III. The study had been approved by the ethics committee of hospital, and the subjects and their family members understood the content of the study and signed an informed consent form.

Inclusion criteria were as follows: premature infants with a gestational age less than 37 weeks, the bodyweight was under 2.5 kg, and the head circumference was under 33 cm.

Exclusion criteria were as follows: premature infant with congenital malformations, those with chromosomal abnormalities and metabolic genetic diseases, and those with craniocerebral abnormalities confirmed by prenatal examination.