Oxytocin, Vasopressin and Prolactin in New Breastfeeding Mothers: Relationship to Clinical Characteristics and Infant Weight Loss

Abstract

Background: Maternal milk production requires the neuropeptide oxytocin. Individual variation in oxytocin function is a compelling target for understanding low milk production, a leading cause of breastfeeding attrition. Complicating the understanding of oxytocin pathways is that vasopressin may interact with oxytocin receptors, yet little is known about the role of vasopressin in lactation. Research aims: The aims of this study were (1) to describe maternal plasma oxytocin, vasopressin, and prolactin patterns during breastfeeding following low-risk spontaneous labor and birth in healthy first-time mothers and (2) to relate hormone patterns to maternal characteristics and breastfeeding measures. Methods: Eligible women were recruited before hospital discharge. Forty-six participants enrolled and 35 attended the study visit. Participants kept a journal of breastfeeding frequency, symptoms of lactogenesis, and infant weight. Plasma samples were obtained at breastfeeding onset on Day 4–5 postpartum, and repeated after 20 min. Hormones were measured with immunoassays. Infant weight change, milk transfer, and onset of lactogenesis were also measured. Results: Baseline oxytocin and vasopressin were inversely related to one another. Oxytocin and prolactin increased significantly across the 20-min sampling period while vasopressin decreased. Higher oxytocin was associated with higher maternal age, lower BMI, shorter active labor, physiologic labor progression, and less weight loss in the newborn. Higher vasopressin correlated with younger maternal age, higher BMI, and greater newborn weight loss. Conclusions: Oxytocin and vasopressin have contrasting relationships with maternal clinical characteristics and newborn weight gain in early breastfeeding infants. Further study is needed to understand how oxytocin and vasopressin influence lactation outcomes.

Maternal plasma levels of oxytocin during breastfeeding—A systematic review

“…Basal levels of oxytocin decreased during the first days postpartum [ 37 ]. Maternal oxytocin levels were shown to rise in connection with the onset of suckling or other types of breast stimulation or skin-to-skin contact immediately after birth [ 14 – 42 ]. In control studies performed without suckling, or in studies of women formula-feeding their infants, no rise of oxytocin was observed [ 18 , 20 , 23 ].…”

“…After removing duplicates and screening of titles and abstracts, two full text papers were included and reviewed. One paper was excluded due to no reporting of oxytocin levels [ 13 ] and one paper met the inclusion/exclusion criteria [ 14 ].…”

“…All together 29 articles were identified in which maternal oxytocin levels were recorded during breastfeeding or other types of breast stimulation [ 14 – 42 ]. Note that the 29 included articles are based on 25 clinical studies, as data from 3 of the clinical studies had been split and published in 2 separate articles, thus [ 20 , 34 ] and [ 30 , 32 ] and [ 36 , 37 ] were based on the same clinical studies.…”

“…papers were included and reviewed. One paper was excluded due to no reporting of oxytocin levels [13] and one paper met the inclusion/exclusion criteria [14].…”

“…The different assays used for oxytocin determination do not give rise to identical values and furthermore the timing of and, in fact also the duration of blood sampling, influences the size of the peaks. In the experiments in which oxytocin levels were measured with ELISA onset levels were high (132-to 1642 pg/mL) and even then peaks of oxytocin were induced by breastfeeding [14,51]. Oxytocin, prolactin, milk production and their relationship with personality traits in women after vaginal delivery or Cesarean section…”