New Insight into Onset of Lactation: Mediating the Negative Effect of Multiple Perinatal Biopsychosocial Stress on Breastfeeding Duration

Background: Many perinatal stressors, including high prepregnancy body mass index, preterm birth, and cesarean section, increase the risk for short breastfeeding duration. Few studies, however, have investigated the mechanism in the relationship between perinatal determinants and breastfeeding duration. This study aimed to test the hypothesis that delayed onset of lactation (OL) could mediate the negative effect of perinatal biopsychosocial stress on breastfeeding duration and to evaluate the impact of new perinatal factors with potentially hazardous effects. Subjects and Methods: Maternal demographic characteristics, health status, and psychological stress during pregnancy were assessed by structured questionnaires and medical records. The information of lactation was collected in the hospital within 1-3 days after delivery. Data on breastfeeding behaviors were obtained through the telephone interview at 2 months after delivery. Results: The risk of delayed OL increased in women who had experienced severe life event stress in the first trimester of pregnancy (adjusted risk ratio [RR] 2.59, 95% confidence interval [CI] 1.52, 4.40), had undergone cesarean section (adjusted RR 2.11, 95% CI 1.46, 3.05), whose gestational body mass index gain were not less than 7.62 (adjusted RR 1.90, 95% CI 1.27, 2.86), and whose breastfeeding frequency was less than three times in the first day after childbirth (adjusted RR 2.14, 95% CI 1.57, 2.91). The final model of structural equation modeling indicated that women with cesarean section, preterm birth, greater gestational body mass index gain, higher scores of stressful life events in the first trimester, and less breastfeeding frequency in the first day after delivery were more likely to experience delayed OL, which could result in an earlier breastfeeding termination. Conclusions: Delayed OL, as a negative biological event resulted from the perinatal biopsychosocial stress, is a key mediator linking perinatal factors to breastfeeding duration. More attention should to be paid to underweight before pregnancy and severe life events during pregnancy, which are regarded as novel and remarkable risk factors of delayed OL and short breastfeeding duration.