A nested case-control study of uterine prolapse.

A nested case-control study was conducted to detect risk factors for periparturient uterine prolapse. Records from 4173 lactations were collected for 5 years from 17 Holstein dairies in the vicinity of Cornell University. Logistic regression was used to model the risk factors for uterine prolapse. Milk fever, dystocia, sex of the calf, and stillbirth were examined as potential risk factors. There was no confounding or effect modification by season of calving and parity. The incidence rate for uterine prolapse was 0.6%. Dystocia and milk fever increased the risk of uterine prolapse five and three times, respectively.