Excess drug prescriptions during influenza and RSV seasons in the Netherlands: potential implications for extended influenza vaccination.

Influenza and respiratory syncytial virus (RSV) infections are responsible for considerable morbidity, mortality and health-care resource use. For the Netherlands, we estimated age and risk-group specific numbers of antibiotics, otologicals and cardiovascular prescriptions per 10,000 person-years during periods with elevated activity of influenza or RSV, and compared these with peri-season rates. Data were taken from the University of Groningen in-house prescription database (www.iadb.nl) and virological surveillance for the period 1998-2006. During influenza and RSV periods excess antibiotic prescriptions were estimated for all age groups. In the age groups 0-1 and 2-4 years, excess antibiotic prescriptions during periods with elevated RSV activity (65% and 59% of peri-seasonal rates) exceeded the surpluses estimated during the influenza-activity periods (24% and 34% of peri-seasonal rates) while for otologicals excess prescriptions were higher for influenza (22% and 27%) than for RSV (14% and 17%). Among persons of 50 years and older, notably those without medical high-risk conditions, excess prescriptions for cardiovascular medications were estimated during the influenza periods at approximately 10% (this was also already seen in persons aged 45-49). Our results may have implications for influenza vaccination policies. In particular, extension of influenza vaccination to groups of non-elderly adults and young children may lower excess prescriptions during these influenza periods for all three types of drug prescriptions investigated.

The documentation of health problems in relation to prescribed medication in people with profound intellectual and multiple disabilities.

BACKGROUND: Persons with profound intellectual and multiple disabilities (PIMD) suffer from a wide range of health problems and use a wide range of different drugs. This study investigated for frequently used medication whether there was a health problem documented in the medical notes for the drug prescribed. METHOD: Persons with PIMD with an estimated intelligence quotient of 25 and profound or severe motor disorders were studied. Data on health problems were taken from medical notes and prescribing data were obtained from pharmacies. Data covering 1 year were analysed. For four therapeutic areas (anticonvulsants, laxatives, drugs for peptic ulcer and gastro-oesophageal reflux disease and psycholeptics), we determined whether we could find an indication for prescribed medication. RESULTS: Some 254 persons with PIMD (46% male, 54% female; median age 49 years, range 6-82) from eight residential facilities participated. Some 226 participants (89%) were prescribed medication over the course of 1 year. An indication for the prescribed medication was documented for 92% (n = 130) (95% confidence interval 88-96%) of 141 participants on anticonvulsants, for 68% (n = 112) (61-75%) of 165 participants on laxatives, for 44% (n = 58) (36-52%) of 132 participants on drugs for peptic ulcer and gastro-oesophageal reflux disease, and for 89% (n = 102) (83-95%) of 115 participants on psycholeptic drugs. CONCLUSIONS: The best level of documentation was found for anticonvulsants the worst for drugs for peptic ulcer and gastro-oesophageal reflux disease. Lack of documenting an indication may be due to off-label use, inadvertent continuation of no longer indicated medication, inadequate documentation and underdiagnosis. Adequate documentation practices are essential because of the communication problems that are characteristic for persons with PIMD.

Antiepileptic drug utilization in children from 1997-2005--a study from the Netherlands.

OBJECTIVE: To investigate the utilization of antiepileptic drugs (AEDs) in Dutch children and compare this with guidelines on the treatment of epilepsy in children. METHOD: From the Dutch Interaction Database (IADB.nl) we selected children aged 0-19 years who received at least one prescription for an AED (ATC-code beginning with N03A) between 1997 and 2005. We calculated cumulative incidences and prevalences per 1000 children per year, stratified by age-category, sex and type of AED, and the total number of months each patient received at least one prescription of AEDs, and we counted the number of person-months and AEDs prescribed. For each AED, proportions of person-months were calculated for mono- and combination therapy. Kaplan-Meier survival analysis was used to analyse the duration of AED use, stratified by sex. RESULTS: The overall prevalence of the prescription of AEDs to children was constant at approximately 4.0 per 1000 children during the years of the study. The overall cumulative incidence from 1997-2005 was 0.67 per 1000 children. When stratified by age category or sex, there were no relevant differences in incidence or prevalence. Valproic acid was the most frequently prescribed drug, followed by carbamazepine and lamotrigine. In 20.3% of all person-months, patients received combination therapy; of these, 34.2% received combination therapy for 3 person-months or less. The older AEDs were prescribed more often as monotherapy than combination therapy, in contrast with the newer AEDs, for which the opposite was true. The 50% survival probability (= time period when 50% of children had stopped using AEDs) was around 2 years, with a significantly lower discontinuation of treatment for girls than boys (P = 0.04). CONCLUSION: The overall cumulative incidence of AEDs was determined to be 0.67 per 1000 children, and the prevalence 4.0 per 1000 children. The most frequently prescribed drug is valproic acid, followed by carbamazepine and lamotrigine. The prescribing of AEDs seems to be in conformity with the overall recommendations of the guidelines on the treatment of epilepsy in children.

Corticosteroid-induced osteoporosis prevention: longitudinal practice patterns in The Netherlands 2001-2005.

UNLABELLED: We investigated prevention trends and predictors for osteoporosis prevention in long term corticosteroid users. The use of bisphosphonates increased from 2001 to 2005. Longer duration of corticosteroid use and DMARD use were predictors for receiving prevention. Females appear reasonably well treated; however, men require more attention. INTRODUCTION: Previous studies have shown that long-term corticosteroid users are undertreated for osteoporosis prevention. Our aim was to identify prevention trends in long-term corticosteroid users from 2001-2005 in The Netherlands and to identify predictors for bisphosphonate prophylaxis. METHODS: Pharmacy dispensing data were used from 9 community pharmacies. All oral corticosteroid doses were converted to "prednisolone equivalents". We then identified long-term (> or =90 days) corticosteroid episodes, which required bisphosphonate prophylaxis as per 2002 Dutch guidelines; Multivariate logistic regression was used to identify predictors for receiving prevention. RESULTS: We identified 615 different corticosteroid patients requiring prophylaxis. From 2001-2005 the use of bisphosphonates increased from 38% to 54% (p = 0.001). In 2005 females were prescribed more bisphosphonates than males (61% vs. 39%; p = 0.002), or any treatment (72% vs. 45%; p < 0.001). Multivariate analysis showed that longer duration of corticosteroid use and disease-modifying anti-rheumatic drug (DMARD) use were independent predictors of bisphosphonate use. Use of respiratory medication was a negative predictor of bisphosphonate use. CONCLUSION: There has been a significant increase in osteoporosis prophylaxis in a population at high risk for osteoporosis/fractures. In particular, females appear reasonably well treated; however, men are still not receiving prevention to the same degree as women.

Drug prescription patterns before, during and after pregnancy for chronic, occasional and pregnancy-related drugs in the Netherlands.

OBJECTIVE: To compare the prescription of drugs in women over a period from 2 years before until 3 months after pregnancy, regarding the type of drugs used and the fetal risk. DESIGN: A cohort study based on pharmacy records of women giving birth to a child between 1994 and 2003. SETTING: The study was performed with data from the InterAction database, containing prescription-drug-dispensing data from community pharmacies. POPULATION: The study population included 5412 women for whom complete pharmacy records were available. METHODS: Drugs were classified into three categories: (1) drugs for chronic conditions, (2) drugs for occasional use and (3) drugs for pregnancy-related symptoms and also classified according to the Australian classification system. MAIN OUTCOME MEASURES: The prescription rate was calculated as the number of women per 100 women who received one or more prescriptions for a given drug within a specified time period. RESULTS: About 79.1% of the women received at least one prescription during pregnancy. The prescription rate for most drugs for chronic diseases and for occasional use decreased during pregnancy, whereas, as expected, the prescription rate for pregnancy-related drugs increased. During the first trimester of pregnancy, 1.7% of all drugs prescribed for chronic conditions and 2.3% of the occasional drugs were classified as harmful. CONCLUSIONS: The increase in prescription rate during pregnancy is caused by an increase in prescription rate of drugs for pregnancy-related symptoms. The prescription of harmful drugs is more commonly associated with drugs for occasional use rather than with drugs for chronic conditions. Therefore, a more cautious prescribing of drugs to healthy women in the fertile age is necessary.

[Use of oral contraceptives in the years 1994-2002: different but not less]. / Gebruik van orale anticonceptiva in de jaren 1994-2002: wel anders, niet minder.

OBJECTIVE: To describe the use of contraceptives among women aged 10-59, particularly in relation to the type of oral contraceptives (OCs) among starting users and women already using OCs. DESIGN: Descriptive. METHOD: Data on the use of medication in the period 1994-2002 by women in the age range 10-59 years were selected from the Interaction Database of North and East Netherlands. The study population was 33,795 women in 1994 and 102,894 in 2002. Cross-sectional studies were performed of prevalent and incident OC users per year and the contribution of the various types of OC was measured. RESULTS: The use of contraceptives among women aged 10-59 years has remained fairly constant since 1994, being about 33%. However, Dutch women started using OCs at an increasingly younger age: 47% of the 15-19-year-olds in 2002 compared with 35% in 1994. The use of third-generation OCs among young starting OC-users (10-19 years of age) in 2002 was very low (3.5% of all OCs). Among women who already used OCs, the switch from third- to second-generation OCs was less pronounced. In 2002, 23% of all OC-users used third-generation preparations compared with 46.5% in 1994. The proportion using cyproteron-ethinylestradiol increased slightly over the years. CONCLUSION: After 1994, mainly second-generation OCs have been prescribed. The switch from third- to second-generation OCs was especially marked among the young starting users. The use of cyproteron-ethinylestradiol increased slightly during the years.

[Hormone replacement therapy in the peri-menopausal and post menopausal period: more than half of the women were treated for more than one year]. / Hormoonsuppletietherapie in de peri- en postmenopauzale periode: bij meer dan de helft van de vrouwen langer dan een jaar.

OBJECTIVE: To describe the use of hormone replacement therapy (HRT) and oral contraceptives (OC) among women in the Netherlands in the 45 to 69 years age group during the year 2002. DESIGN: Descriptive. METHOD: Pharmaceutical data on 42,032 women who were in the 45-69 years age group on 31 December 2002 was selected from the InterAction database, a collection of community pharmacy data from the north of the Netherlands. The duration of the therapy was investigated for women who had received at least one HRT or OC prescription in 2002. RESULTS: Oral contraceptives were used by 11.3% of women aged 50-54 years and 1.8% of women aged 55-59 years. The prevalence of HRT ranged from 6.0% to 11.7% depending on age. Of these users (n = 3885) 28.6% used an oestrogen-progestagen preparation. A treatment period of more than one year was found in 62.3% of women aged 45-49 years and 82.6% of women aged 55-59 years. In particular, preparations containing just oestrogen had been used for a longer period; 43.4% had used these for more than 5 years. CONCLUSION: More than half of the women who used HRT had done so for more than one year.

Concomitant prescribing of benzodiazepines during antidepressant therapy in the elderly.

A follow-up study was performed in two ambulatory cohorts aged > or =65 to investigate whether the prevalence and incidence of anxiolytic/hypnotic benzodiazepine drug prescribing is comparable between users of serotonin reuptake inhibitors (SSRIs) and users of tricyclic antidepressants (TCAs). The prevalence and incidence of benzodiazepines during antidepressant therapy was estimated among users of TCAs and SSRIs. Coprescribing of benzodiazepines occurred in 53% of the TCA users and 57% of the SSRI users (prevalence RR 1.1; CI(95) 0.9-1.2). The average duration of benzodiazepine drug use was >65 days per 100 days of antidepressant use. During SSRI therapy, significantly more people started benzodiazepine drug therapy than during TCA therapy (incidence rate ratio (RR) 1.7; CI(95) 1.2-2.4). Analyses repeated 5 years later yielded similar results (overall incidence RR(MH) 1.6; CI(95) 1.3-2.0). These data indicate that SSRI use is associated with a significantly higher chance of starting benzodiazepines compared with TCA use.

Prescribing of gastroprotective drugs among elderly NSAID users in The Netherlands.

BACKGROUND: Use of non-steroidal anti-inflammatory drugs (NSAIDs) is associated with an increased risk of gastrointestinal toxicity, in particular when risk factors are present. METHODS: A study was performed to investigate concomitant prescribing of gastroprotective agents (H2-receptor antagonists, proton pump inhibitors, or misoprostol) in an ambulatory cohort of NSAID users aged 65 years and over. The prevalence of concomitant prescribing was studied, as well as the prophylactic prescribing of gastroprotective drugs. A stepwise logistic regression was performed to determine predictive variables of prophylactic and concomitant gastroprotective drug prescribing. RESULTS: Co-prescribing of gastroprotective drugs occurred in 1522 (23%) (of which 944 concerned prophylactic prescribing) of the NSAID users (n = 6557), with an average duration of 67 days per 100 days of NSAID use. Co-prescribing of gastroprotective drugs varied among individual NSAIDs. Concomitant use of oral corticosteroids (ORadj 2.4; Cl95 2.0-2.9), coumarins (ORadj 1.6; Cl95 1.3-2.0), and low dose aspirin (ORadj 1.6; Cl95 1.4-1.9) were significantly associated with both prophylactic and concomitant prescribing of gastroprotective agents during NSAID therapy. DISCUSSION: Despite current guidelines recommending gastroprotective drug prescribing among high risk groups, the rate of concomitant prescribing of gastroprotective agents in NSAID users aged 65 years and over is low. Feedback to prescribers should be given to improve prescribing practices in this high risk group.

Drug utilisation in Dutch nursing homes.

OBJECTIVE: To quantify and evaluate drug utilisation in a sample of Dutch nursing homes. METHODS: A retrospective analysis of computerised medication data of 2355 residents aged 65 years and over from six nursing homes in the Netherlands was performed. For each therapeutic drug group, the number of users was determined. The ten therapeutic groups used most frequently were investigated further. For these, patient characteristics, use of therapeutic subgroups, the average daily dosages and the chronicity of drug use were determined. Chronicity was expressed as the percentage of treatment days divided by the number of residents' days in the nursing home. RESULTS: During the study period, 89%, 77% and 56% of the study population used a drug from the anatomical therapeutic chemical (ATC) main group N (nervous system), A (alimentary tract and metabolism) and C (cardiovascular system), respectively. Eight of the ten therapeutic drug groups prescribed most frequently were used for more than 50% of the time. In particular, psycholeptic drugs, diuretics and laxatives were used chronically (83%, 81%, and 80% of the nursing home stay, respectively). Except for a few drug groups, such as laxatives and diuretics, the prescribed daily dosages were relatively low. Twenty-eight percent of the residents received loop diuretics; these were prescribed in relatively high dosages. CONCLUSION: Drug utilisation in the nursing homes was high and many drugs were used chronically. In view of the risk of possible adverse effects and drug-drug interactions, the prescribing and dosage of psycholeptic drugs, laxatives, loop diuretics and ulcer-healing drugs should be re-evaluated, carefully.

Predictors for prophylactic antithrombotic prescribing in ischaemic heart disease and the impact of national guidelines.

OBJECTIVES: Assessment of predictors for initiating prophylactic antithrombotic prescribing for patients newly diagnosed with ischaemic heart disease (IHD) and the impact of the introduction of national guidelines. DESIGN AND SETTING: A retrospective case-control study was performed using pharmacy prescription data from 120,000 Dutch patients over a 5-year period. IHD patients were identified using as a marker multiple nitrate prescriptions [anatomical-chemical-therapeutic (ATC) code CO1D] indicating chronic use. Initiation of antithrombotic therapy was likewise identified using ATC codes B01AA and B01AC (oral anticoagulants and thrombocyte aggregation inhibitors), prescribed within 6 months following the first nitrate prescription. Statistically significant (P<0.05) predictors were assessed using multivariable analysis considering patient, prescriber and medication characteristics. RESULTS: Of the 2598 patients who met specified inclusion criteria for newly diagnosed IHD, approximately 35% was not prescribed any type of antithrombotic therapy. Male patients [odds ratio (OR) 2.4, 95% confidence interval (CI) 2.0-2.9], patients with cardiovascular (other than IHD) and diabetic co-morbidity (OR 6.4, 95% CI 4.8-7.9 and OR 1.6, 95% CI 1.1-2.1, respectively) and patients using isosorbide mononitrate rather than isosorbide dinitrate as anti-ischaemic main therapy (OR 2.1, 95% CI 1.3-2.5) were most likely to be prescribed antithrombotic therapy. Furthermore, initiating antithrombotic prescribing was more likely after the introduction of national guidelines (OR 1.4, 95% CI 1.1-1.7). CONCLUSIONS: Initiating antithrombotic prescribing in newly diagnosed IHD patients can be predicted by patient gender, certain co-morbidity and main type of nitrate therapy. The introduction of national guidelines has resulted in an increase of prophylactic antithrombotic prescribing in accordance with their contents.

Prescription data as a tool in pharmacotherapy audit (II). The development of an instrument.

In many countries, prescription data are used as an instrument to provide feedback on prescribing. This article describes the development and implementation of a computer program as a tool for pharmacotherapy audit meetings and it illustrates the possibilities of such a program. The program was developed to support the optimisation of prescribing in the various stages of behavioural change. It enables pharmacists to make sophisticated overviews of prescribing by physicians in their audit group and furthermore, pharmacists can conduct drug utilisation studies or pharmaco-epidemiological studies in their own patient population. Forty percent of Dutch pharmacies have purchased the computer program since its introduction; it was distributed together with a technical handbook and a course book, which elaborated on the types of graphs available and their interpretation. An educational course was developed regarding the optimal selection and interpretation of graphs. Examples of prescription data as a tool to support various aims of audit meetings are given. The program is acknowledged as a welcome contribution to pharmacotherapy audit and to the pharmacists' advisory role in pharmacotherapy.

Constipation as an adverse effect of drug use in nursing home patients: an overestimated risk.

AIMS: To investigate whether results from case control and cross sectional studies which suggest an association between laxative use and other drug use could be confirmed in a cohort study of nursing home patients. METHODS: A prospective cohort study of 2355 nursing home patients aged 65 years and over was performed to estimate the incidence relative risk of constipation associated with drug use. The study was conducted with prescription sequence analysis of each resident's detailed pharmacy records and data on morbidity and mobility. RESULTS: Use of drugs, which according to the summaries of product characteristics (SPC) and the literature on adverse drug effects have moderately to strongly constipating properties, was associated with a relative risk of 1.59 (95% CI 1.24-2.04) for the occurrence of constipation during exposure time. Use of drugs with mildly to moderately constipating effects was not associated with laxative use (RR 1.13; 95% CI 0.93-1.38). Stratification on the level of age, gender, type of nursing (psychogeriatric or somatic), morbidity, number of medications taken and mobility showed no confounding effects of these variables on outcome measurements. These variables all acted as effect modifiers. Effect of age and number of medications taken on the relative risk was nonlinear. CONCLUSIONS: Although an association between drugs that exhibit moderately to strongly constipating effects and occurrence of constipation was found, the risk was not as high as seen in previous studies. The high prevalence of constipation in nursing home patients is only partly due to adverse drug effects.

Oral contraceptive use before and after the latest pill scare in The Netherlands. Changes in oral contraceptive use and how users change.

In October 1995, a "pill scare" developed in Europe. In the Netherlands, the recommendations given were 1) to not alarm women without risk for deep vein thrombosis (DVT), and 2) to be reserved in prescribing third generation oral contraceptives (OC) for young women who were beginning OC use. To determine whether there is a change in the prescription of third generation OC after the latest pill scare, prescription data from 1/10/94 to 1/10/96, covering a population of +/- 120,000 persons, were studied with respect to OC use before and after the pill scare. Trend analyses revealed a significant decline in third generation compared with total OC prescribing only in the youngest age category (p = 0.0034). Further, switch behavior was studied. Switches from third to second generation OC were more prevalent after the pill scare than before (odds ratio = 2.63; 95% confidence interval 1.84-3.75) and switches from second to third generation OC were significantly less prevalent after the pill scare. This indicates that Dutch prescribers have reacted to the pill scare in the way that the government recommended.

PIP: In response to studies demonstrating a moderately increased risk of deep vein thrombosis in users of third-generation oral contraceptives (OCs) with pre-existing risk factors for this condition, the UK Committee on Safety of Medicines issued a statement in October 1995 urging providers to advise OC acceptors of this finding. While some European countries imposed strict limits on the use of third-generation OCs, others decided to await publication of the OC studies. The present study assessed the impact of the "pill scare" on OC use in the Netherlands, where the recommendations were 1) not to alarm women without risk of deep vein thrombosis and 2) to be conservative in prescribing third-generation OCs for young women initiating OC use. Trend analyses were conducted of prescription data from 12 pharmacies in the northeastern part of the Netherlands covering the period from January 1, 1994, to January 10, 1996. A significant decline in third-generation compared with total OC prescribing was found during the study period only in the youngest age group (under 20 years). After the pill scare, the incidence rate of switches from second- to third-generation OCs compared with switches from one second-generation OC to another was less than before (odds ratio (OR), 0.50; 95% confidence interval (CI), 0.36-0.70). Compared with switches from one third-generation OC to another, switches from a third- to a second-generation OC increased (OR, 2.63; 95% CI, 1.84-3.75). These findings indicate that the 1995 pill scare had resulted in slight changes in Oc use that are consistent with recommendations issued by Dutch health authorities.

Vulvo-vaginal candidiasis associated with acitretin.

The aim of this study was to estimate the risk of vulvo-vaginal candidiasis among the users of acitretin. The incidence rate ratio of vulvo-vaginal candidiasis was estimated in a cohort of acitretin users by using prescription sequence analysis. Study subjects were 196 women between 15 and 45 years of age, exposed to acitretin in 1990. Prescriptions of drugs for treatment of vulvo-vaginal candidiasis were used as proxy for the occurrence of vulvo-vaginal candidiasis. Validation of the proxy drug was performed by record linkage of pharmacy and medical records. In addition to the risk estimation by incidence rate ratios a case-crossover study with patient-stratified logistic regression analysis was performed to control for distortion due to individual differences in contribution of exposure time. The positive predictive value of the proxy drug for vulvo-vaginal candidiasis ranged between 57 and 100%, the sensitivity was 87% and the specificity estimated 99%. The crude incidence rate ratio for vulvo-vaginal candidiasis following acitretin exposure was 2.8 (CI95%: 1.1-7.1). The pooled Mantel-Haenszel incidence rate ratio was 3.3 (CI95%: 1.1-9.6) after stratification for accumulated level of exposure. Patient-stratified analysis on the subgroup of cases (n = 15) revealed an odds ratio of 6.5 (CI95%: 2.3-18.2). This study strongly suggests that the higher occurrence of vulvo-vaginal candidiasis during acitretin exposure is attributable to the drug.

Handling of risk-bearing drugs during pregnancy. Do we choose less risky alternatives?

The drug use of nearly 2,000 pregnant women was evaluated at the level of the individual patient for the drugs belonging to the Australian risk categories B3, C and D. The pattern of changes in the use of these drugs is studied in terms of women who discontinue (d), continue (c) or begin (b) using the drug during pregnancy. The ratios d/(c+b) and d/b were the highest for the drugs belonging to the high-risk groups and the lowest for drugs from the low-risk categories. This suggests a congruence between theoretical knowledge and daily practice. Patients who had already been using a drug for a long time before pregnancy, more frequently continued using that drug than patients who had been using the drug only incidentally before. The described daily dose for the riskful drugs was approximately 20% lower in patients who started to use a drug during pregnancy compared to those who continued drug use. The data from this analysis indicate that the prescribing physician is generally aware of the possible risks of drug use during pregnancy. The d/(b+c) and d/b ratios are shown to be a good measure of prescribing behaviour in relation to pregnancy and can be used to compare knowledge of theory and daily practice.

Ovulation-inducing drugs: a drug utilization and risk study in the Dutch population.

This study describes the use of the ovulation stimulating drugs clomifene, human chorionic gonadotropin (hCG) and human menopausal gonadotropin (hMG) in a representative sample of a population of Dutch women in the child-bearing age group. Clomifene or hMG/hCG are seldom used alone. A considerable percentage of the women received at least four different ovulation-inducing and related drugs during the observation period of two years. Thirty percent of the women who used clomifene were treated for 6 or more cycles. These findings argue for a relative "overuse" and "misuse" of clomifene. Buserelin, a drug not registered for the indication ovulation induction in The Netherlands but used in in vitro fertilization (IVF) programs as inhibitors of pituitary gonadotropin production, was nevertheless prescribed to 38% of the hMG /hCG users and to 11 % of the clomifene users. Our study indicates that, though the potential risks of congenital malformations due to clomifene are difficult to assess, they may be considerable; this, and the fact that different ovulation-inducing drugs are used together with clomifene, emphasizes the need for post-marketing surveillance.

Investigating drug use in pregnancy. Methodological problems and perspectives.

In this study the use of prescribed drugs before, during and after pregnancy is described. The study is based on data obtained from pharmacy records of 1,948 women who delivered a live-born infant. Different measures to evaluate drug exposure are used. During the nine months of pregnancy 86% of the women used on average 4.2 prescriptions. During the course of pregnancy the use of gastro-intestinal and blood-forming drugs increased, whereas the use of cardiovascular, antiphlogistic and central nervous system drugs decreased. Anti-emetics were predominantly used in the first trimester, and antacids in the last trimester, whereas laxatives were especially used after delivery. The percentage of women who used a treatment for vaginal infections increased from 2 to 7 during pregnancy. Most of the women (73%) received one or more iron prescriptions during the course of pregnancy, however, the prescribed daily dose was low (prescribed daily dose/defined daily dose = 0.6). At least 1% of the women filled a new prescription for anticonceptives in the first trimester of pregnancy. Most likely, our data reflect the general prescribing pattern for Dutch pregnant women who delivered a live-born baby. Therefore, they form a good and detailed base for further studies, for instance, on the exposure to drugs with known or suspected risks or on the use of drugs in patients with chronic concomitant diseases. Such studies may lead to recommendations that may improve prescribing behaviour.