Development and validation of a model for predicting the risks for delayed onset of lactogenesis stage II for Chinese pregnant women.

Delayed onset lactogenesis II has adverse effects on breastfeeding and neonatal health. This study aimed to determine the risk factors of DOL II, develop a predictive model for DOL II, and test its validity. This was a retrospective cohort study. A total of 450 pregnant women were involved in this study, including 112 cases with DOL II and 338 cases without DOL II, who were hospitalized between October 2023 and April 2024. Univariate and multivariate logistic regression analyses were conducted to determine the risk factors of DOL II, which were then included in the nomogram. The performance of the nomogram model was evaluated by the area under the receiver operating curve, calibration curve, and Hosmer-Lemeshow test. Decision curve analysis was used to evaluate the clinical efficacy of the nomogram. The results showed that maternal age, pre-pregnancy BMI, gestational age, parity, delivery mode, length of stage II labor, gestational diabetes, EPDS, maternal-infant separation, breastfeeding education during pregnancy, formula use, and onset of breastfeeding within the first hour were independent risk factors. In the derivation cohort, the AUC was 0.786. Youden index was 1.526, with a sensitivity of 0.781 and a specificity of 0.745. In the verification cohort, AUC was 0.748. The nomogram model has good consistency and performance, which can identify women who are at high risk of DOL II.