The pregnancy category of a pharmaceutical

Medication

A pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease.- Classification :...

 agent is an assessment of the risk of fetal injury due to the pharmaceutical, if it is used as directed by the mother during pregnancy

Pregnancy

Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...

. It does not include any risks conferred by pharmaceutical agents or their metabolites that are present in breast milk.

Every drug has specific information listed in its product literature

Product literature

Product literature is a primary subset of business publishing specifically geared toward the selection, purchase and use of a business' products....

. In the UK, while no preset categories are applied, the British National Formulary

British National Formulary

The British National Formulary is a medical and pharmaceutical reference book that contains a wide spectrum of information and advice on prescribing and pharmacology, along with specific facts and details about all medicines available on the National Health Service , including indication,...

 gives a table of drugs to be avoided or used with caution in pregnancy, and does so using a limited number of key phrases.

United States

In 1979, the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 Food and Drug Administration

Food and Drug Administration

The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...

 (FDA) introduced a classification of fetal risks due to pharmaceuticals

Drug

A drug, broadly speaking, is any substance that, when absorbed into the body of a living organism, alters normal bodily function. There is no single, precise definition, as there are different meanings in drug control law, government regulations, medicine, and colloquial usage.In pharmacology, a...

. This was based on a similar system that was introduced in Sweden one year earlier.

The United States FDA has the following definitions for the pregnancy categories:

United States FDA Pharmaceutical Pregnancy Categories
Pregnancy Category A	Adequate and well-controlled human studies have failed to demonstrate a risk to the fetus in the first trimester of pregnancy (and there is no evidence of risk in later trimesters).
Pregnancy Category B	Animal reproduction studies have failed to demonstrate a risk to the fetus and there are no adequate and well-controlled studies in pregnant women OR Animal studies have shown an adverse effect, but adequate and well-controlled studies in pregnant women have failed to demonstrate a risk to the fetus in any trimester.
Pregnancy Category C	Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.
Pregnancy Category D	There is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experience or studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.
Pregnancy Category X	Studies in animals or humans have demonstrated fetal abnormalities and/or there is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experience, and the risks involved in use of the drug in pregnant women clearly outweigh potential benefits.

One characteristic of the FDA definitions of the pregnancy categories is that the FDA requires a relatively large amount of high-quality data on a pharmaceutical for it to be defined as Pregnancy Category A. As a result of this, many drugs that would be considered Pregnancy Category A in other countries are allocated to Category C by the FDA. See below.

The FDA has proposed updating its approach to labeling http://edocket.access.gpo.gov/2008/pdf/E8-11806.pdf

Australia

Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

 has a slightly different pregnancy category system from the United States - notably the subdivision of Category B. The system, as outlined below, was established by the Congenital Abnormalities Sub-committee of the Australian Drug Evaluation Committee

Australian Drug Evaluation Committee

The Australian Drug Evaluation Committee or ADEC, was a committee that provided independent scientific advice to the Australian Government regarding therapeutic drugs. The committee was originally formed in 1963 and more recently authorised under the Therapeutic Goods Act 1989 as part of the...

 (ADEC).

ADEC Pregnancy Categories (Australia)
Pregnancy Category A	Drugs which have been taken by a large number of pregnant women and women of childbearing age without an increase in the frequency of malformations or other direct or indirect harmful effects on the fetus having been observed.
Pregnancy Category B1	Drugs which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals have not shown evidence of an increased occurrence of fetal damage.
Pregnancy Category B2	Drugs which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals are inadequate or may be lacking, but available data show no evidence of an increased occurrence of fetal damage.
Pregnancy Category B3	Drugs which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals have shown evidence of an increased occurrence of fetal damage, the significance of which is considered uncertain in humans.
Pregnancy Category C	Drugs which, owing to their pharmaceutical effects, have caused or may be suspected of causing, harmful effects on the human fetus or neonate without causing malformations. These effects may be reversible.
Pregnancy Category D	Drugs which have caused, are suspected to have caused or may be expected to cause, an increased incidence of human fetal malformations or irreversible damage. These drugs may also have adverse pharmacological effects.
Pregnancy Category X	Drugs that have such a high risk of causing permanent damage to the fetus that they should NOT be used in pregnancy or when there is a possibility of pregnancy.

The subcategorisation of Category B, while offering additional information which may be of benefit in evaluating the risk vs benefit, presents its own problem of data reliability - since human data is lacking or inadequate, the subcategorisation is based on animal data. Furthermore, allocation of a drug in Category B does not necessarily imply greater safety than Category C.

Drugs in Category D are not absolutely contraindicated in pregnancy, unlike Category X. In some cases Category D was assigned to a drug on the basis of suspicion.

Germany

Category	Description
Gr 1	Extensive human tests and animal studies have not shown the drug to be embryotoxic / teratogenic.
Gr 2	Extensive human tests of the drug have not shown the drug to be embryotoxic / teratogenic.
Gr 3	Extensive human tests of the drug have not shown the drug to be embryotoxic / teratogenic. However, the drug appears to be embryotoxic / teratogenic in animals.
Gr 4	No adequate and well-controlled studies of the drug's effects on humans are available. Animal studies have shown no embryotoxic / teratogenic effects.
Gr 5	No adequate and well-controlled studies of the drug's effects on humans are available.
Gr 6	No adequate and well-controlled studies of the drug's effects on humans are available. Animal studies have shown embryotoxic / teratogenic effects.
Gr 7	There is a risk that the drug is embryotoxic / teratogenic in humans, at least in the first trimester.
Gr 8	There is a risk that the drug is toxic to fetuses throughout the second and third trimesters.
Gr 9	There is a risk that the drug causes prenatal complications or abnormalities.
Gr 10	There is a risk that the drug causes hormone specific action on the human fetus.
Gr 11	There is a known risk that the drug is a mutagen/carcinogen.

Categorization of selected agents

The data presented is for comparative and illustrative purposes only, and may have been superseded by updated data.

Classification of some agents, based on different national bodies
Pharmaceutical agent	Australia	United States
Acetaminophen/Paracetamol Paracetamol Paracetamol INN , or acetaminophen USAN , is a widely used over-the-counter analgesic and antipyretic . It is commonly used for the relief of headaches and other minor aches and pains and is a major ingredient in numerous cold and flu remedies...	A	B
Acetylsalicylic acid/Aspirin Aspirin Aspirin , also known as acetylsalicylic acid , is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication. It was discovered by Arthur Eichengrun, a chemist with the German company Bayer...	C	D
Amoxicillin Amoxicillin Amoxicillin , formerly amoxycillin , and abbreviated amox, is a moderate-spectrum, bacteriolytic, β-lactam antibiotic used to treat bacterial infections caused by susceptible microorganisms. It is usually the drug of choice within the class because it is better absorbed, following oral...	A	B
Amoxicillin with clavulanic acid Co-amoxiclav Amoxicillin/clavulanic acid or co-amoxiclav is a combination antibiotic consisting of amoxicillin trihydrate, a β-lactam antibiotic, and potassium clavulanate, a β-lactamase inhibitor...	B1	B
Cefotaxime Cefotaxime Cefotaxime is a third-generation cephalosporin antibiotic. Like other third-generation cephalosporins, it has broad spectrum activity against Gram positive and Gram negative bacteria...	B1	B
Diclofenac Diclofenac Diclofenac is a non-steroidal anti-inflammatory drug taken to reduce inflammation and as an analgesic reducing pain in certain conditions....	C	C
Isotretinoin Isotretinoin Isotretinoin, INN, is a medication used mostly for cystic acne. It was first developed for brain, pancreatic and other cancers. It is used to treat harlequin-type ichthyosis, a usually lethal skin disease, and lamellar ichthyosis. Its effects are systemic and nonselective...	X	X
Leflunomide Leflunomide Leflunomide is a medication of the DMARD type, used in active moderate to severe rheumatoid arthritis and psoriatic arthritis. It is a pyrimidine synthesis inhibitor.-Basic chemical, pharmacological, and marketing data:...	X	X
Loperamide Loperamide Loperamide , a synthetic piperidine derivative, is an opioid drug used against diarrhea resulting from gastroenteritis or inflammatory bowel disease. In most countries it is available generically and under brand names such as Lopex, Imodium, Dimor, Fortasec, and Pepto Diarrhea Control...	B3	B
Paroxetine Paroxetine Paroxetine is an SSRI antidepressant. Marketing of the drug began in 1992 by the pharmaceutical company SmithKline Beecham, now GlaxoSmithKline...	C	D
Phenytoin Phenytoin Phenytoin sodium is a commonly used antiepileptic. Phenytoin acts to suppress the abnormal brain activity seen in seizure by reducing electrical conductance among brain cells by stabilizing the inactive state of voltage-gated sodium channels...	D	D
Rifampicin Rifampicin Rifampicin or rifampin is a bactericidal antibiotic drug of the rifamycin group. It is a semisynthetic compound derived from Amycolatopsis rifamycinica ...	C	C
Thalidomide Thalidomide Thalidomide was introduced as a sedative drug in the late 1950s that was typically used to cure morning sickness. In 1961, it was withdrawn due to teratogenicity and neuropathy. There is now a growing clinical interest in thalidomide, and it is introduced as an immunomodulatory agent used...	X	X
Theophylline Theophylline Theophylline, also known as dimethylxanthine, is a methylxanthine drug used in therapy for respiratory diseases such as COPD and asthma under a variety of brand names. Because of its numerous side-effects, the drug is now rarely administered for clinical use. As a member of the xanthine family, it...	A	C
Tetracycline	D	D
Triamcinolone Triamcinolone Triamcinolone is a long-acting synthetic corticosteroid given orally, by injection, inhalation, or as a topical ointment or cream.... (skin)	A	C