Intrapartum Epidural Fentanyl and Breastfeeding in the Immediate Postpartum Period: a Randomized, Controlled, Double-blinded Study

Although intrapartum epidural analgesia is frequently implicated in adverse breast-feeding outcomes, many previous studies feature major design limitations that preclude widespread applicability of findings. Some fail to control for the precise pharmacologic composition of the epidural infusion, including whether or not an opioid, such as fentanyl, is even used at all in addition to local anesthetic or whether a combined spinal/epidural or purely epidural technique is used. The drugs used in epidural infusions not only have different mechanisms of action and lipophilicities but are also transferred across the placenta in varying proportions, with one study identifying an umbilical vein/maternal vein ratio of 0.94 for epidural fentanyl and 0.30 for bupivacaine, and another finding significantly different umbilical cord fentanyl concentrations among neonates whose mothers' epidural infusions contained \>150 micrograms fentanyl, \<150 micrograms, or none at all. It is also possible that the same total dose of epidural fentanyl could affect neonates differently depending upon the time course over which it was administered - namely, whether fentanyl is included in both the initial epidural bolus and the subsequent infusion or solely in the infusion. In two studies, mean umbilical vein concentrations of fentanyl did not correlate with total epidural infusion time, but both of these featured sample sizes fewer than 30, necessitating further research. Another limitation of some previous studies is defining success solely as the time to cessation of breast-feeding. Questionnaires mailed to mothers months or even years postpartum may generate unreliable data. If epidural medications truly mediate some physiologic effect upon breast-feeding, then the optimal study period is immediately post-delivery, specifically before the drugs are cleared from the maternal and neonatal circulations. After hospital discharge, many new factors - such as a mother's need to return to work or la