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Prescribing in pregnancy—therapeutic discrimination?

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It is estimated that 10% of pregnant women have a chronic medical disorder that requires regular use of medicines. In addition, some women develop health problems during pregnancy, and at least 40% take a prescription drug at some point.1,2 The impact of the increasing age and body mass index of the population has contributed to the proportion of women who require medication during pregnancy. For example, 4% of women delivering in England and Wales in 2011 were aged 40 years or over (compared with 1% in the 1990s) and 19% of women of child-bearing age in England in 2008 were obese.3,4 The relative lack of information on the use of medicines during pregnancy remains an area of concern for healthcare professionals.

Indirect maternal deaths in the UK, where a new or pre-existing medical or mental health problem is aggravated by pregnancy, have almost doubled in the last 20 years and exceed direct maternal deaths by 50%.5 The leading causes include cardiac conditions, neurological disorders, sepsis, thromboembolism and mental health problems. Yet it is clear that prescribing of, and adherence to, medication in pregnancy can be poor; many patients being wary of taking medicines when there is so little published evidence on the risks and benefits. Doctors are afraid of causing harm and the spectre of thalidomide-induced phocomelia continues to haunt healthcare professionals.6 The summary of product characteristics often advises that a drug should be used only if the benefits outweigh the risks, even though the risks may not have been properly identified. Drug companies and researchers generally exclude pregnant women from trials even when the medication is likely to be used by women of childbearing age. Trials aimed specifically at pregnant women in whom physiological changes, placental transfer kinetics and foetal exposure might be studied are rare.7 Although there are complex ethical issues associated with studying drugs in pregnant women, some researchers argue that it is unethical not to obtain dosing information for drugs that are frequently used by pregnant women. However, in the absence of robust trials, adverse effects can take many years to become apparent: sodium valproate was hailed as a wonder anticonvulsant in the 1960s, linked with neural tube defects in the 1980s and associated with adverse neurodevelopmental effects in the offspring with third trimester exposure in the 2000s. With increasing awareness that the intrauterine environment is important for long-term development of children, it is ever more important that those involved in drug development and trials look for ways to safely involve pregnant women rather than automatically exclude them.

Over recent years our approach to prescribing for children has improved significantly, helped by changes in legislation in the USA and Europe. For example, between 2008 and 2011, 13 new medicines as well as 30 new indications and nine new pharmaceutical forms of existing medicines were authorised for use in children.8 We need a similar approach for drug use in pregnancy so that we are not always saying “no” or “don't know” to pregnant women who need medication.2 The British National Formulary is cautious in its advice regarding drug use in pregnancy and refers readers to other sources of information that include the UK Teratology Information Service ( More input is needed from the pharmaceutical industry and medicine regulatory bodies with greater emphasis on research, registry data collection, wider availability of information, increased integration of information sources and the development of shared-decision aids for patients and healthcare professionals. Pregnancy is a natural state that has been ignored by the pharmaceutical industry for too long.


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