Frequency and Variety of Medication Use Among Pregnant Women

FREQUENCY AND VARIETY OF MEDICATION USE AMONG PREGNANT WOMEN

In the United States alone, 119 new drug or biologic applications were approved by the Food and Drug Administration (FDA) in 2004. In the same year, an additional 147 approvals were issued by the FDA for new or expanded uses of currently marketed drugs or biologics (U.S. FDA, 2005). New drugs do not come to market with clinical trial safety data specifically designed to address questions related to human preg-nancy. Once a new drug is available for clinical use, or a previously marketed drug is approved for a new indication, the frequency with which it is prescribed and the specific medical conditions that it is used to treat influence the likelihood that women of reproduc-tive age and pregnant women will use the drug.

However, numerous studies have demonstrated that pregnant women are commonly using several medications over the course of gestation. For exam-ple, in a review of drug utilization studies, Bonati et al. (1990) identified 13 publications originating from sites in the United States and Europe in which pregnant women used an average of 4.7 drugs per person with the mean number ranging from 3 to 11. A 1996 survey of records of the French Health Insur-ance Service demonstrated that in a sample of 1000 women living in southwest France, 99% of women received a prescription for at least one drug during pregnancy with a mean of 13.6 medications prescribed per woman (Lacroix et al., 2000). Similarly, a 2004 study conducted across eight health maintenance orga-nizations in the United States, in which prescription records for 152 531 pregnant women were reviewed, found that 64% of these women were prescribed at least one drug other than a vitamin or mineral some-time during pregnancy. Moreover, 39% of all women in the sample received at least one prescription during the first trimester. On average, women received 2.7 drug dispensings and 1.7 different chemical entities over the course of pregnancy (Andrade et al., 2004).

In addition to the frequent occurrence of prescrip-tion medication use during pregnancy, recent evidence suggests that over-the-counter medications are used even more commonly. Using two large case–control data sets, Werler et al. (2005) demonstrated that acetaminophen, ibuprofen and pseudoephedrine were used by at least 65%, 18% and 15% of pregnant women, respectively. Furthermore, for some over-the-counter medications, use was reportedly higher during pregnancy than in the period before conception.

Given that a substantial proportion of pregnancies occur without prior planning – in the United States estimates are that as many as 56% of pregnancies are not planned – women may be inadvertently exposed to medications before pregnancy is recognized, and this vulnerable period may extend into the first 4–6 weeks or longer following conception (Forrest, 1994). Thus, unintentional fetal exposures can occur during part or all of the most critical period in embryonic development for drug-induced malformations.

In addition to medication exposures that take place before pregnancy recognition, many maternal condi-tions, both acute and chronic, may require treatment after pregnancy is confirmed. A variety of relatively common diseases that occur in women of reproductive age may necessitate treatment throughout the course of pregnancy. For example, the prevalence of clinical depression among women in their reproductive years is estimated to be as high as 8.0%–20.0% (Kessler et al., 1993), asthma 3.7%–8.4% (Kwon, Belanger and Bracken, 2003), epilepsy 0.4%–1.0% (Yerby, 2000; Holmes, Wyszynski and Lieberman, 2004) and rheumatoid arthritis and other autoimmune disorders 1.0%–2.0% (Belilos and Carsons, 1998). For some of these maternal conditions, a decision not to treat (or to under treat) could lead to events, such as uncontrolled seizure activity or psychiatric episodes, which could be detrimental to the woman, the pregnancy and/or the fetus itself (Goldberg and Nissim, 1994; Bracken et al., 2003; Cohen et al., 2006). Thus, the develop-ment of adequate information on drug safety in preg-nancy involves two equally important objectives: the identification of potentially harmful exposures that might be avoided or managed and the establishment of acceptable margins of safety for drugs that offer potential benefit to women during their pregnancies.