A Population-Based Prescription Study of Asthma Drugs during Pregnancy: Changing the Intensity of Asthma Therapy and Perinatal Outcomes

Abstract

Background: Among the goals of gestational asthma, therapy is optimisation of pulmonary function. According to the US Food and Drug Administration, no asthma drugs can be considered ‘safe’ during pregnancy. Fear of adverse fetal effects may thus lead to restrictive use of asthma drugs during pregnancy, and no population-based studies concerning gestational asthma therapy exist. Objectives: To examine whether asthma drugs or changing intensity of asthma therapy during pregnancy was associated with deviations from expected values of gestational age, birth weight, length at birth, or malformations. Methods: The Birth Registry was used to identify all 15,756 primiparous women who gave birth in the County of North Jutland between 1991 and 1996. According to the North Jutland Prescription Database, 303 of these women received prescriptions for asthma drugs during pregnancy. Women who did not purchase any prescription drugs during pregnancy constituted the reference group. Conclusion: Women who received prescriptions for asthma drugs during pregnancy gave birth to infants with birth weight and length at birth within the expected limits. Reducing intensity of asthma treatment during pregnancy was associated with lower birth weight and length at birth. This may indicate that pregnant women chose to discontinue therapy although their disease severity justifies continuation of treatment. However, analyses did not take into account important clinical variables, and results could also be due to confounding factors or chance.

Asthma during pregnancy: mechanisms and treatment implications

“…Historical cohort studies (table 1) conducted prior to ICS use [10], or where subjects were either not on any preventer treatment [11] or reduced their use of ICS during pregnancy [18], also support the conclusion that ICS medication may protect against low birth weight in pregnant females with asthma. Pre-term labour or delivery is associated with the use of oral steroids [31,33] and theophylline [31], or having a respiratory problem during the pregnancy [24], suggesting that this may be an effect of more severe asthma or asthma exacerbations.…”

“…In particular, asthma requiring hospitalisation during pregnancy [26,56], or asthma that is not treated with ICS [18,30] may increase the risk of low birth weight. The greatest risk factor for pre-term labour and delivery, based on recent large prospective cohort studies, is oral steroid and theophylline use [31,33].…”

“…A Danish population-based study collected data from a birth registry and prescriptions database (1991)(1992)(1993)(1994)(1995)(1996) to study the use of asthma medications by pregnant females and relate this to perinatal outcome [18]. Less than 2% of all Danish females were prescribed asthma medications during pregnancy.…”

“…This was particularly evident among 22 females who decreased their medication use from inhaled steroid to inhaled b 2 -agonist. This study was limited by a lack of information regarding compliance and the reasons for alterations in asthma management [18]. These may have included a clinical improvement in lung function and asthma symptoms, or may have been due to a reduction in prescribing as a result of fears of drug use during pregnancy.…”

Effects of asthma severity, exacerbations and oral corticosteroids on perinatal outcomes

“…Several studies have reported a relationship between increased asthma severity or decreased asthma control and increased risk of low birth weight, small for gestational age and pre-term delivery [6][7][8][9][10][11][12][13][14][15][16][17][18]. One recent meta-analysis found that pregnant asthmatic females with a history of severe exacerbation during pregnancy are at a significantly increased risk of perinatal complications including low birth weight [19].…”