Methadone

For pregnant and postpartum women with opioid dependence in treatment, methadone maintenance has been the treatment of choice in the United States, Canada, and many other countries. In contrast to other substances, concentrations of methadone in human milk and the effects on the infant have been studied. The concentrations of methadone found in human milk are low, and all authors have concluded that women on stable doses of methadone maintenance should be encouraged to breastfeed if desired, irrespective of maternal methadone dose. *

* Refs. , , , , , , , , , .

The current thought is that environmental risk factors combine with prenatal exposures to promote epigenetic changes in gene expression and methylation patterns that have both immediate and long-term implications related to developmental programming. Note that these findings relate to infants exposed to methadone both prenatally and after birth via breastfeeding, and there is little information available on infants with chronic methadone exposure via breastfeeding alone.

In addition, about 70% of infants born to women prescribed methadone during pregnancy will experience neonatal abstinence syndrome (NAS), the constellation of signs and symptoms often presenting following in utero opioid exposure. Infants with significant NAS can experience difficulties with attaching and sucking/swallowing during breastfeeding that can impact their ability to breastfeed. However, given that there is increasing evidence supporting the conclusion that there is a reduction in the severity and duration of treatment of NAS when mothers on methadone maintenance therapy breastfeed, breastfeeding for these dyads should be encouraged. (II-1, II-3) Unfortunately, the rate of breastfeeding initiation in this cohort is generally low, less than half that reported in the U.S. general population. A small recent qualitative study demonstrated that lack of support from the health care community and misinformation about the dangers of breastfeeding while on methadone therapy are significant, yet modifiable, barriers to breastfeeding success in these women. Given the benefits to these mothers and infants to remain on methadone maintenance therapy and breastfeed, it is important for us to provide robust ongoing support for this vulnerable group.

Buprenorphine

Buprenorphine is a partial opioid agonist used for treatment of opioid dependency during pregnancy in some countries and increasingly in the United States. Multiple small case series have examined maternal buprenorphine concentrations in human milk. All concur that the amounts of buprenorphine in human milk are small and are unlikely to have short-term negative effects on the developing infant. In one study, 76% of 85 maternal-infant pairs breastfed, with 66% still breastfeeding 6 to 8 weeks postpartum. The breastfed infants had less severe NAS and were less likely to require pharmacological intervention than the formula-fed infants, similar to methadone discussed earlier, although this did not reach statistical significance with the size of the sample studied.

Other Opioids

Use of opioids in the United States has increased substantially over the past decade. A retrospective cross-sectional analysis of NAS in hospital births in the years from 2000 to 2009 found an increase in incidence from 1.2 to 3.39 per 1000 births. Antepartum maternal opioid use was also found to have risen from 1.19 to 5.63 per 1000 hospital births from 2000 to 2009; any use of opioids was included in data collection. A recent Centers for Disease Control and Prevention Morbidity and Mortality Weekly Report highlighted data demonstrating that approximately one third of women of reproductive age filled a prescription for opioids each year between 2008 and 2012.

When use of narcotics during pregnancy is determined to be consistent with an opioid use disorder rather than a modality for short-term pain relief, consideration of initiation of maintenance methadone or buprenorphine as previously discussed is strongly encouraged, and these mothers should be supported in breastfeeding initiation. (III) Short courses of most other low-dose prescription opioids can be safely used by a breastfeeding mother, but caution is urged with codeine, as CYP2D6 ultra-rapid metabolizers may experience high morphine (metabolite) blood levels, and there has been a single case report of a breastfeeding neonatal death after maternal use. (III) Information is lacking on the safety of breastfeeding when moderate to high doses of opioids are used for long periods of time. There is also a lack of information available about transitioning mothers from short-acting opioids to opioid maintenance therapy while breastfeeding rather than during pregnancy.

Marijuana

Uniform guidelines regarding the varied use of marijuana by breastfeeding mothers are difficult to create and cannot hope to cover all situations. The legality of possessing and using marijuana varies greatly from country to country; in the United States, there are increasing numbers of states where it is legal for “medicinal use” with a prescription, and a few states where it is legal for “recreational use,” but under federal law, it remains illegal in all states. Therefore, basing recommendations on marijuana use and concurrent breastfeeding from a purely legal standpoint becomes inherently complex, problematic, and impossible to apply uniformly across all settings and jurisdictions. As laws shift and marijuana use becomes even more common in some areas, it becomes increasingly important to carefully weigh the risks of initiation and continuation of breastfeeding while using marijuana with the risks of not breastfeeding while also considering the wide range of occasional, to regular medical, to heavy exposure to marijuana.

In addition to the potential legal risk, the health risks to the infant from the mother’s marijuana use must be carefully considered. Δ9-Tetrahydrocannabinol (THC), the main compound in marijuana, is present in human milk up to eight times that of maternal plasma levels, and metabolites are found in infant feces, indicating that THC is absorbed and metabolized by the infant. It is rapidly distributed to the brain and adipose tissue and stored in fat tissues for weeks to months. It has a long half-life (25 to 57 hours) and stays positive in the urine for 2 to 3 weeks, making it impossible to determine who is an occasional versus a chronic user at the time of delivery by urine toxicology screening. Evidence regarding the effects of THC exposure on infant development via breastfeeding alone is sparse and conflicting, and there are no data evaluating neurodevelopmental outcomes beyond the age of 1 year in infants who are only exposed after birth. Also notable in this discussion of risk is that the potency of marijuana has been steadily increasing, from about 3% in the 1980s to 12% in 2012, so data from previous studies may no longer even be relevant. Additionally, current concern over marijuana use during lactation stems from possible infant sedation and maternal inability to safely care for her infant while directly under its influence; however, this remains a theoretical problem and has not been well established in the literature.

Human and animal evidence examining the behavioral and neurobiological effects of exposure to cannabinoids during pregnancy and lactation shows that the endocannabinoid system plays a crucial role in the ontogeny of the central nervous system and its activation, during brain development. As Campolongo et al. concluded, cannabinoid exposure during critical periods of brain development can induce subtle and long-lasting neurofunctional alterations. Several preclinical studies highlight how even low to moderate doses during particular periods of brain development can have profound consequences for brain maturation, potentially leading to long-lasting alterations in cognitive functions and emotional behaviors. Exposure to second-hand marijuana smoke by infants has been associated with an independent two times possible risk of sudden infant death syndrome (SIDS) (III); because breastfeeding reduces the risk of SIDS, this needs to be additionally considered. Thus careful contemplation of these issues should be fully incorporated into the care plans of the lactating woman in the setting of THC use. Breastfeeding mothers should be counseled to reduce or eliminate their use of marijuana to avoid exposing their infants to this substance and advised of the possible long-term neurobehavioral effects from continued use. (III)

Alcohol

Use of alcohol during pregnancy is strongly discouraged, as it can cause fetal alcohol syndrome, birth defects, spontaneous abortion, and premature births, among other serious problems. (III) Many women who significantly decrease or eliminate their alcohol intake during pregnancy may choose to resume consuming alcohol after giving birth, with approximately half of breastfeeding women in Western countries reported to consume alcohol at least occasionally. Alcohol interferes with the milk ejection reflex, which may ultimately reduce milk production through inadequate breast emptying. (III) Human milk alcohol levels generally parallel maternal blood alcohol levels, and studies evaluating infant effects of maternal alcohol consumption have been mostly mixed, with some mild effects seen in infant sleep patterns, amount of milk consumed during breastfeeding sessions, and early psychomotor development. (III) Possible long-term effects of alcohol in maternal milk remain unknown. Most sources advise limiting alcohol intake to the equivalent of 8 oz of wine or two beers, and waiting 2 hours after drinking to resume breastfeeding. (III) To ensure complete elimination of alcohol from breastmilk, mothers may consult a normogram devised by the Canadian Motherisk program to determine length of time needed based on maternal weight and amount consumed. (III)

Tobacco

Approximately two thirds as many pregnant women as nonpregnant women smoke tobacco, with decreasing numbers of women smoking as pregnancy progresses. Many mothers quit during pregnancy, but postpartum relapse is common, with about 50% resuming tobacco use in the first few months after birth. Data on the epidemiology of breastfeeding mothers who smoke cigarettes remains complex, and smoking in many series has been found to be associated with reduced rates of breastfeeding. Nicotine and other compounds are known to transfer to the infant via milk, and considerable transfer of chemicals via second-hand smoke also occurs when infants are exposed to environmental tobacco smoke. Increases in the incidence of respiratory allergy in infants and in SIDS are just two significant well-known risks of infant exposure to environmental tobacco smoke. (III) Most sources endorse promotion of breastfeeding in the setting of maternal smoking while vigorously supporting smoking cessation. (III) Some smoking cessation modalities (nicotine patch, nicotine gum, and possibly buproprion) are compatible with breastfeeding and can be encouraged in many circumstances. (III)