1. Blackburn, Susan PhD, RN, FAAN

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This column is part of an ongoing series on selected Internet and other resources that are useful for clinical practice or teaching. The focus of this column is on examples of online and print resources for information on the effects of drugs during pregnancy and lactation on the fetus and infant.


Surveys of drug utilization by pregnant women found that 59% to 94% take at least 1 prescribed drug (in addition to vitamins and iron) during their pregnancy.1-4 The fetus is a passive recipient of prescribed, over-the counter and illicit drugs and herbal agents entering the maternal system. These substances may cross the placenta and have an effect on the fetus and newborn. Over-the-counter, prescribed, and abused drugs have the potential to act as teratogens and alter embryonic and fetal development. "A teratogen is any substance, organism, physical agent, or deficiency state present during gestation that is capable of inducing abnormal postnatal structure or function (biochemical, physiologic, or behavioral) by interfering with normal embryonic and fetal development."5(p212) Other potential teratogens include infectious agents, ionizing radiation, hyperthermia, pesticides, metal (eg, mercury and lead), organic solvents, and excess or deficient nutrients.5


The majority of breast-feeding women take at least 1 prescribed drug during lactation.6,7 Drugs and environmental agents can cross the blood-milk barrier into human milk and have the potential to affect the infant. Most of these agents are found at levels significantly lower than those in the mother. Breast-feeding may be interrupted or discontinued for maternal therapy; however, this often does not need to happen as relatively few maternal medications are incompatible with breast-feeding.5,6 If the mother is on drugs with potential risks, these can be discussed along with the benefits of continued breast-feeding and "careful monitoring and strategies to minimize infants' exposure can be often used so that the mother can decide to continue breastfeeding if she chooses."5(p218)


For many drugs, teratogenic risks are not known or data are sparse.8-10 Information about drugs used during pregnancy and breast-feeding and concerns or potential hazards of specific agents can be found in general print reviews,11-19 reviews of specific classes of drugs,20-27 and online resources. Examples of free online resources include the following.


InfantRisk Center ( from Texas Tech University Health Sciences Center (Director: Thomas W. Hale) provides information on risks of medications use during pregnancy and breast-feeding either online or via the InfantRisk Helpline at 806-352-2519 (encouraged for specific questions). Online information is available via pages on specific topics and via Web forums on Medications and Breastfeeding Mothers and Medications and Pregnancy. Access is also currently available to Dr Hale's older Web forums from his earlier site. The InfantRisk Center also includes a series of forums for mothers with special conditions (such as multiple sclerosis, depression bipolar disorder, low milk volume, and others) where they can meet and discuss breast-feeding or pregnancy issues associated with their condition. An InfantRisk Center mobile App can be purchased for rapid access to information about information about prescription and nonprescription medications and their safety during pregnancy and breast-feeding.


LactMed, which is part of the National Library of Medicine Toxicology Data Network (TOXNET), is a database of drugs and other chemicals that breast-feeding mothers may be exposed to and can be accessed at This Web site includes information on the levels of various substances in breast milk and in the infant's blood and possible adverse effects.


Organization of Teratology Information Specialists (OTIS) is an organization of teratology information services in the United States and Canada. OTIS provides free telephone consultation to professionals and the public about possible effects of specific drugs or other substances during pregnancy and exposures during breast-feeding at 866-626-6847. The OTIS Web site at has lists of member groups, fact sheets about selected exposures information about their annual conference, and links to other resources.


MotherRisk ( is a Canadian site (and OTIS affiliate) that provides online, print, and telephone resources on drugs and other risks during pregnancy and lactation. The site includes both professionals and mothers Web sites, several toll-free help lines, and links to information on specific topics.


Pregnancy drug exposure registries have been established to collect experiences with specific drugs or groups of drugs (such as antiepileptic agents) during pregnancy and fetal and neonatal outcomes. Many of these registries have been developed by pharmaceutical companies; others are from individual academic sites or are population-based. Several of these registries are run by ORIS. A list of some sites is available at


-Susan Blackburn, PhD, RN, FAAN


Professor Emeritus


Department of Family and Child Nursing


University of Washington, Seattle




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