Introduction

There is too little information on the impact of prescribed medicines on breastfeeding and breastfed infants. Families’ questions usually focus on the compatibility of the medicines with breastfeeding, and whether breastfeeding will leave infants vulnerable to adverse drug reactions from maternal medicines. However, the more insidious and pervasive harm from reduced breastfeeding rates following administration of medicines in late pregnancy, labour and postpartum is a more common and potentially soluble problem.

 Do prescribed medicines reduce the chances of successful breastfeeding?

Some medicines affect the biological processes of lactation, for example: amphetamines, antidepressants, oestrogens, aripiprazole, possibly diuretics, alcohol, oxytocin and opioids (Anderson 2017a,b). Systematic review suggests that prescription medicines, marijuana, and pesticides reduce breastfeeding rates and duration, due to weak suckling, adverse effects on infants and families’ concerns (Jordan et al 2023). Early discontinuation of breastfeeding is associated with mental health medicines, antidepressants and antiepileptics: we found that 22% of women using antidepressants were breastfeeding at 6 weeks, compared with 33% of women not prescribed antidepressants and 26% of unmedicated women with depression (Jordan et al 2019).

Opioids administered in labour by any route are sedative and may affect infants’ ability to root and latch, and oxytocin may weaken the milk-ejection reflex. Data from systematic reviews (Heeson et al 2021) and large cohorts indicate that medicines used in labour are associated with lower breastfeeding rates (Jordan et al 2009, Andrew 2022). Risks appear to increase with the dose of opioid received (Jordan et al 2005).

 Do infants suffer adverse drug reactions (ADRs) following exposure via breastmilk?

Most maternal medicines are safe for most infants. The benefits of breastfeeding outweigh the risks of harm from exposure to most medicines; however, the British National Formulary (BNF, 2023) reports exceptions, including some medicines prescribed for severe mental illness, cancer or conditions affecting the immune system. Seriously ill women may need powerful medicines where there is little or no information on breastfeeding in humans.

 Although healthy term neonates are able to remove most medicines from their bodies, the kidneys and livers of some preterm and sick infants may not be fully functional, risking accumulation of medicines and adverse effects. For some medicines, such as codeine, a few infants are genetically vulnerable to severe adverse reactions, and reviews suggest considerable variation in infants’ ability to metabolise maternal medicines (Jordan et al 2022). There is a remote possibility that even small amounts of a substance in breastmilk may trigger hypersensitivity or allergic responses (BNF 2023). Accordingly, infants should be monitored for the adverse effects of maternal medicines.  

Responding to the challenges: collective responsibility  

The professional group best suited to supporting women and monitoring infants should be identified at policy and practice level. These should not be ‘orphan tasks’.

Prescribers and pharmacists

• Women of childbearing age using long-term medicines need to discuss optimising prescribing for pregnancy and breastfeeding pre-conception, before and after birth, and in response to the results of infant monitoring.  

Midwifery and obstetric teams

• Women whose labours have been medicated should receive targeted breastfeeding support postpartum and over the first few days.
• Where women are using medicines long-term, practical support, and reassurance based on infant monitoring are needed. Many women using long-term medicines successfully breastfeed, and short-term support can overcome initial difficulties.

Primary care teams: community nurses, health visitors (in some countries), pharmacists, and doctors

• Information on prescription use is available to healthcare professionals: these electronic systems should be used to identify women needing support during pregnancy and breastfeeding.
• Women using prescription medicines are at risk of early discontinuation of breastfeeding.

• Infants should be checked regularly for adverse effects of prescription medicines in breastmilk. If sedative medicines, including mental health medicines, opioids or antiepileptics are used, infants must be monitored regularly for sleep duration, feeding difficulties, weight gain, and development. Standard, routine checks are insufficient, and additional contacts should be scheduled to pre-empt problems and offer reassurance.

• Women also need support to adhere to their prescription regimens, and reassurance that their infants are not being harmed by medicines in breastmilk. Women with long-terms conditions may discontinue their medicines whilst breastfeeding, jeopardising their own health (Scime et al 2023). We found that women discontinuing their asthma medicines had lower breastfeeding rates than more seriously affected women adhering to prescribed regimens (Davies et al 2020).

Policy makers

• Breastfeeding, infant development and medicines adherence are surrounded by social stigma, making for difficult conversations for busy professionals. Using protocols, checklists and decision support helps professionals by legitimising awkward questions on difficult topics. However, no structured monitoring protocols are available, and these should be developed and implemented as soon as possible.
• The pharmaco-epidemiology of breastfeeding is characterised by the absence of whole-population databases with information on breastfeeding, infant outcomes and prescribing (Jordan et al 2002, 2023). There is almost no information on hospital prescribing. Policy makers should ensure that data are available on all maternal and infant outcomes.

Sources of information

LACTMED: Drugs and lactation database (lactmed). In.: Bethesda (MD): National Library of Medicine (US); 2006.

 References

 Anderson P: Drugs that suppress lactation, part 1. Breastfeed Med 2017, 12:128-130, PMID: 28394656 DOI: 10.1089/bfm.2017.0012,

Anderson P: Drugs that suppress lactation, part 2. Breastfeed Med 2017, 12:199-201 PMID: 28338339 DOI: 10.1089/bfm.2017.0029

Andrew MS, Selvaratnam RJ, Davies-Tuck M, Howland K, Davey MA. The association between intrapartum interventions and immediate and ongoing breastfeeding outcomes: an Australian retrospective population-based cohort study. International breastfeeding journal. 2022;17(1):48.

Davies G, Jordan S, Thayer D, Tucker D, Humphreys I (2020) Medicines prescribed for asthma, discontinuation and perinatal outcomes, including breastfeeding: A population cohort analysis. PLOS ONE 15(12): e0242489. https://doi.org/10.1371/journal.pone.0242489

Heesen P, Halpern SH, Beilin Y, Mauri PA, Eidelman LA, Heesen M, Orbach-Zinger S. Labor neuraxial analgesia and breastfeeding: An updated systematic review. J Clin Anesth. 2021 Feb;68:110105. doi: 10.1016/j.jclinane.2020.110105. Epub 2020 Oct 15. PMID: 33069970.

Joint Formulary Committee. British National Formulary. 85^th ed. London: BMJ and Pharmaceutical Press; 2023

Jordan S, Bromley R, Damase-Michel C, Given J, Komninou S, Loane M, Marfell N, Dolk H. Breastfeeding, pregnancy, medicines, neurodevelopment, and population databases: the information desert. Int Breastfeed J. 2022 Aug 2;17(1):55. doi: 10.1186/s13006-022-00494-5. PMID: 35915474. https://internationalbreastfeedingjournal.biomedcentral.com/articles/10.1186/s13006-022-00494-5

Jordan S, Davies GI, Thayer DS, Tucker D, Humphreys I (2019) Antidepressant prescriptions, discontinuation, depression and perinatal outcomes, including breastfeeding: A population cohort analysis. PLOS ONE 14(11): e0225133. https://doi.org/10.1371/journal.pone.0225133

Jordan S, Emery S, Watkins A, Evans J, Storey M, Morgan G. Associations of drugs routinely given in labour with breastfeeding at 48 hours: analysis of the Cardiff Births Survey. BJOG 2009; 116(12) 1622-30 DOI: 10.1111/j.1471-0528.2009.02256.x.

Jordan S., Emery S., Bradshaw C., Watkins A., Friswell W. 2005 The Impact of Intrapartum Analgesia on Infant Feeding. BJOG: An International Journal of Obstetrics and Gynecology. 112, 927-34.  http://onlinelibrary.wiley.com/doi/10.1111/j.1471-0528.2005.00548.x/full  

Jordan S, Komninou S, Lopez Leon S (2023) Where are the data linking infant outcomes, breastfeeding and medicine exposure? A systematic scoping review. PLOS ONE 18(4): e0284128. https://doi.org/10.1371/journal.pone.0284128

Scime NV, Metcalfe A, Nettel-Aguirre A, Tough SC, Chaput KH. Association of postpartum medication practices with early breastfeeding cessation among mothers with chronic conditions: A prospective cohort study. Acta Obstet Gynecol Scand. 2023 Apr;102(4):420-429. doi: 10.1111/aogs.14516. Epub 2023 Jan 27. PMID: 36707933; PMCID: PMC10008275.