Exposure to some widely used labor medications may negatively impact a newborn’s ability to breastfeed successfully, according to a recently published study in the journal Birth: Issues in Perinatal Care.
Previous research exploring the relationship between obstetric drug use and neonatal activities has produced conflicting results.
In a new study, investigators at Loma Linda University Medical Center examined intrapartum exposure to two common labor drugs, fentanyl, a synthetic opioid, and synthetic oxytocin (synOT), and their potential impact on infants’ likelihood of suckling within the first hour after birth.
Nursing immediately following birth, the researchers note, has been shown in other studies to increase other desirable breastfeeding outcomes.
To look at the effects of fentany and synOT on infants’ ability to suckle, Kajsa Brimdyr, PhD, and colleagues at the Healthy Children Project, East Sandwich, MA, recruited healthy, clinically uncomplicated mother–infant dyads. Eligible participants included women aged 18 years or older who were 37–42 weeks pregnant and had planned for a vaginal birth. Inclusion criteria for infants included full-term gestation, good health, and no known abnormalities. Study subjects self-selected to labor either without any pain medication or with epidural anesthesia.
After birthing, the newborns were “placed ventrally on the mother’s bare chest in a semireclined position, dried and covered with a warm blanket.” Per routine hospital procedure, the infants maintained skin-to-skin contact with their mothers for at least the first hour following birth, unless there was a medical reason to remove the infant.
Babies were monitored as they were allowed to move unassisted through Widström’s Stages–nine instinctive patterns of normal neonatal behavior that occur immediately after birth. The eighth stage, suckling, “involves the baby self attaching to the nipple and initiating breastfeeding.”
To track the infants’ activities just after birth, video researchers were positioned behind the mothers’ heads to film their actions.
Of the 63 mother–infant pairs who completed the study, 10 women received no synOT and no fentanyl during labor, while 25 received both drugs. Sixteen received fentanyl alone, and 12 received synOT without fentanyl.
Epidurals Squelch Suckling
Using a logistic regression, the investigators analyzed the likelihood of babies suckling shortly after birth relative to the amount of fentanyl their mothers received during labor. Three independent variables — fentanyl (p = 0.01), synOT (p = 0.026), and Apgar score at 5 minutes (p = 0.046) — were all identified as significant predictors for whether or not an infant suckled in the first hour.
The amount and duration of epidural fentanyl and the amount of synOT were all found to be negatively correlated with suckling immediately after birth.
These data indicate a “dose-dependent inverse relationship between the likelihood of achieving suckling within the first hour 
after birth” and increased fentanyl exposure (p = 0.001, R2 = 0.264, constant significant at 0.05, CI 0.987, 0.997). The researchers explain that the number of infants who began nursing within an hour is “related to the amount of fentanyl in a stepwise decreasing pattern,” with the decrease in suckling beginning at approximately 150 mcg of fentanyl (Brimdyr, K. et al. Birth. 2015; 42(4): 319-328).
The study protocol permitted medical personnel to remove the infants from direct contact with their mothers for periods of 10 minutes or less for medical examinations. Notably, there were no differences in nursing between babies that stayed in continuous skin-to-skin contact with their mothers after birth and those that were removed from skin-to-skin contact for less than 10 minutes.
Dr. Brymdir’s data suggest that epidural fentanyl and synOT exposure adversely impacts newborn behavior, which could contribute to breastfeeding difficulties later in infancy. The authors acknowledge that the relationship is complex, and that further exploration of the combined effects of synOT and fentanyl is necessary in order to draw definitive conclusions.
In the meantime, they note that the correlation between the drugs and infants’ likelihood of suckling after birth “should be taken into account when considering risks and benefits of administering these medications during the course of labor management.”
They urge any mothers desiring to breastfeed their babies to carefully evaluate all risks when considering the use of labor medications.
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