Drugs in Pregnancy and Breastfeeding

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Suggestions for Prescribing Medication in Pregnant Women

    When possible:
  • Use medication only if absolutely indicated.
  • Avoid initiating therapy during the first trimester.
  • Select a medication with a proven track record in human pregnancy.
  • Use a single-agent.
  • Use the lowest effective dose.
  • Discourage the use of over-the counter drugs that might interact with prescription medications.

  Modified from:  Norwitz ER, Greenberg JA.Antibiotics in pregnancy: are they safe? Rev Obstet Gynecol. 2009
PMID: 19826569

Prescription Drugs of Choice During Pregnancy
      Medications recommended as first line agents during pregnancy by various organizations and authorities .

  • Breastfeeding and Maternal Medication(PDF file)
        World Health Organization, 2002
  • Daily Med Package insert information on prescription drugs.
  • Common Drugs of Abuse National Institute on Drug Abuse web site for physicians and other health professionals.
  • DART Database Developmental and Reproductive Toxicology Database - References to developmental and reproductive toxicology literature.
  • Drugs in Pregnancy Motherisk's published studies on the safety or risk of specific drugs during pregnancy
  • Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk Classic text by  Briggs GG, Freeman RK, Yaffe S.J.
  • Drugs, Pregnancy, and Lactation Archive of Ob.Gyn.News articles written by Lee Cohen, Gerald G. Briggs, and Gideon Koren.
  • Drug Safety in Lactation
     Presciber Update
  • FDA Use in Pregnancy Ratings  (Obsolete)
  • InfantRisk Forums  
    LactMed -Drugs and Lactation Database (LactMed) - A peer-reviewed and fully referenced database of drugs to which breastfeeding mothers may be exposed. Among the data included are maternal and infant levels of drugs, possible effects on breastfed infants and on lactation, and alternate drugs to consider.
  • MotherToBaby (Organization of Teratology Information Specialists) has compiled "fact sheets" on various exposures of concern. Fact Sheets answer frequently asked questions about exposures during pregnancy.
  • Motherisk
  • OBPharm
  • Office of Dietary Supplements
  • Pregnancy Drug Registries
  • Prescribing medicines in pregnancy database
  • Reprotox
     Fee required
      Download Acrobat Reader

    Factors that Appear to Determine the Extent of Placental Transfer of Drugs Administered to the Mother [1-5]
    • The molecular weight of the drug; Drugs with molecular weights (MW)  less than 500 D appear to cross the placenta easily, drugs with MW greater than 500  have  incomplete transfer across the human placenta. Drugs with very high MW , such as insulin with a M.W ~ 5800 do not normally cross the placenta.
    • The pKa (pH at which the drug is 50% ionised); Strongly dissociated acid drug molecules should have an incomplete transfer, but this does not seem to be an absolute rule
    • Physiological properties of the placenta (blood flow, gestational age)
    • Expression and activity of metabolizing enzymes and efflux transporters (e.g. ATP-binding cassette (ABC) transporters ). For example placental 11beta-hydroxysteroid dehydrogenase 2 (11beta-HSD2) enzyme inactivates prednisolone by interconversion into
      prednisone , and ABC transporters pump tenofovir disoproxil fumarate  from trophoblast back to maternal circulation.
    • The extent of drug binding to plasma protein does not appear to influence the type of drug transfer across the human placenta to a significant degree.

    1.Pacifici GM, Nottoli R. Placental transfer of drugs administered to the mother. Clin Pharmacokinet. 1995 Mar;28(3):235-69. PMID:7758253
    2. Menon RK, et. al. Transplacental passage of insulin in pregnant women with insulin-dependent diabetes mellitus. Its role in fetal macrosomia. N Engl J Med. 1990 Aug 2;323(5):309-15. Erratum in: N Engl J Med 1992 Jan 23;326(4):280. PMID:2195347
    3. van Runnard Heimel PJ, et al., The transplacental passage of prednisolone in pregnancies complicated by early-onset HELLP syndrome. Placenta. 2005 Nov;26(10):842-5.PMID: 16226134
    4. Neumanova Z, et. al Interactions of tenofovir and tenofovir disoproxil fumarate with drug efflux transporters ABCB1, ABCG2, and ABCC2; role in transport across the placenta.AIDS. 2014 Jan 2;28(1):9-17. PMID:24413260
    5. Hemauer SJ, et al., Role of human placental apical membrane transporters in the efflux of glyburide, rosiglitazone, and metformin.Am J Obstet Gynecol. 2010 Apr;202(4):383.e1-7. doi: 10.1016/j.ajog.2010.01.035.
    36. Nausea and vomiting of pregnancy. Practice Bulletin No. 153. American College of Obstetricians and Gynecologists. Obstet Gynecol 2015;126:e1224. PMID:26287788

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