Effect of postpartum anxiety on the colostral milk beta-endorphin concentrations of breastfeeding mothers.

Peripartal maternal apprehension and anxiety are associated with abnormal labour, dystocia and higher rates of fetal and maternal morbidity. Since colostral beta-endorphin (beta-EP) concentrations are twofold higher than circulating levels, we hypothesised that substantial maternal emotional distress in puerperium might induce consistent changes in colostral beta endorphin galactopoiesis. To test this hypothesis, we assessed the effects of postpartum maternal anxiety (State-Trait Anxiety Inventory-Y form, Spielberger CD, Palo Alto, CA, USA, 1983) on colostral milk beta-EP levels (beta-endorphin 125I RIA, INCSTAR Corporation-Stillwater, Minnesota, USA) in a population of healthy lactating mothers, on the fourth postpartum discharge day, 14 after at term vaginal delivery, 14 after premature (> or = 34 <37 gestational weeks) vaginal delivery, and 14 after elective cesarean section. The colostral milk beta-EP concentrations of mothers who vaginally delivered at term or prematurely were significantly higher on the fourth postpartum day (6.0+/-0.5 and 6.6+/-0.7 vs. 4.3+/-0.4 pmol/l, respectively; P <0.05) than colostral levels of mothers who underwent caesarean section. At the same time, while trait anxiety levels (T, age corrected values) were unaffected by route and mode of delivery, in mothers presenting increased colostral milk beta-EP galactopoiesis after vaginal delivery there was a statistically significant negative correlation (r-0.40; P <0.03) between colostral milk beta-EP concentrations and trait anxiety levels. These data indicate that the labour pain and the vaginal delivery process play a central role in increasing colostral opioid availability for the breastfed neonate; peripartal maternal anxiety is a negative psychobiological determinant in opioid galactopoiesis, and possibly in the postnatal development of several related biological functions of growing infants.