The use, perceptions and knowledge of safety of over-the-counter medications during pregnancy in a Canadian population

Abstract

Introduction

Over-the-counter (OTC) medications and herbal/alternative therapies are more commonly used in pregnancy than prescribed medications despite limited research on their safety.^{1 –4} OTC medications often are used without physician awareness, ² and many pregnant women consume more than one agent at a time.^5,6 Nausea and vomiting occurs in approximately 70% of pregnancies, and common treatments include OTC medications and herbal therapies. ⁷ Pregnant women also frequently use OTC medications to treat allergy, respiratory, gastrointestinal, and skin conditions, and for mild pain control. Acute/short-term illnesses have been reported as indication for OTC medications in about two-thirds of exposed pregnancies, with chronic conditions accounting for close to one-fifth. ⁸

The reported prevalence of prenatal OTC use has ranged from 28% in the United Arab Emirates, ⁹ 30% in low-income countries, ¹⁰ 55% in Ethiopia, ¹¹ and 60%–90% in the United States.^5,12,13 Despite these high rates of prenatal OTC medication use, a comprehensive review of current evidence of OTC medications in pregnancy concluded important knowledge gaps still exist, ¹⁴ with others suggesting little or no information about reproductive toxicity in humans for most OTC medications. ² Among pregnant women in the United Kingdom, important themes relating to prenatal medication experiences included a fear of medications and self-regulation, feeling overmedicated, and conflicting opinions. ¹⁵ Prenatal OTC medication has been considered a global reproductive health concern. ¹⁴ No studies in Canada have assessed OTC medication use in pregnant women. Our objectives were therefore to estimate the prevalence of prenatal OTC medication use and assess knowledge of OTC medication safety in a Canadian population of pregnant women.

Methods

A cross-sectional study was conducted in women attending a hospital obstetrics clinic in Eastern Ontario, Canada’s most populous province. All pregnant women and those within 6 months post-partum could participate; there were no exclusion criteria. The obstetrics clinic is within a third-level academic hospital with a catchment population of 500,000, with approximately 2000 deliveries annually. The survey questions (Supplemental Attachment) were based on a previously validated questionnaire, ⁹ and collected information on demographics, OTC medication use (analgesics, antihistamines, cold medications, herbal supplements) 1–2 months before conception and during pregnancy, and knowledge of OTC medication safety. Pre-conception OTC medication use could be distinguished from pregnancy use. Free text responses were also collected and are reported. The first three digits of the participant’s postal code were used to classify the respondent as having urban or rural residence. Data collection took place at intervals during November 2019 to February 2020.

Results

Seventy-two women completed the survey, a majority of whom reported using at least one OTC medication during pregnancy (N = 63, 87.5%); 13 women (18%) initiated OTC medications in pregnancy. OTC medication use by trimester of pregnancy was 55.6% in the first, 65.3% in the second, and 47.2% in the third trimesters. OTC medication use 1–2 months before conception also was common (73.6%). The most frequently used prenatal OTC medication was acetaminophen (N = 52, 73.2%), followed by aspirin (N = 8, 11.3%), ibuprofen (N = 4, 5.6%), and cold and flu medications (N = 3, 4.2%). Other OTC medications women reported using prenatally included Tums^® (5.6%), Gravol^® (2.8%), Pepto-Bismol^® (1.4%), Ranitidine^® (1.4%), NeoCitran^® (1.4%), and Unisom^® (1.4%). One woman reported using essential oils (peppermint, lavender, and frankincense) in pregnancy. No women reported herbal medication use.

The characteristics of the women by prenatal OTC medication use are shown in Table 1. Compared to women who did not use OTC medications in pregnancy, women who used OTC medications in pregnancy were more likely to have used OTC medications in the 1–2 months before conception. No other characteristics were statistically significantly different by prenatal OTC medication use. Most participants were Caucasian (90.3%), had a college/university degree (69.4%) with a mean age of 30.6 ± 5.7 years. Of the 16 women with a chronic disease (22.2%), asthma was most prevalent (N = 6 women who used OTC medications in pregnancy); the one woman who did not use any OTC medication in pregnancy with a chronic condition had psoriatic arthritis. Other chronic diseases included discord lupus, depression, anxiety, gastroesophageal reflux disease, hypothyroidism, interstitial cystitis, psoriatic arthritis, fibromyalgia, allergies, celiac disease, and Alport syndrome.

The study population was a convenience sample of women attending the site, with data collection affected by COVID lockdowns. To assess the representative of the survey participants to the pregnancy population at the study site, the characteristics of women who completed the survey were compared to women who delivered at the study site in 2019 using de-identified BORN data. The underlying pregnancy population had a mean age of 30.3 ± 5.1 years, 23.9% had a chronic condition, and approximately 40% lived in rural areas, comparable to the survey respondents (Table 1). BORN data were incomplete for prenatal OTC medication use.

Women’s self-reported level of knowledge of OTC medication safety did not differ by use in pregnancy, with most reporting medium-level knowledge (Table 1). Most women self-reported that not all OTC medications are safe prenatally (95.8%). Free text comments from women on the safety of OTC medications included there is not enough information about what pregnant women can take when they are sick; that while OTC medications are “safe” to take during pregnancy there was apprehension to take them; that OTC medications are contraindicated during pregnancy unless recommended by a doctor; that ibuprofen is not safe during pregnancy but is preferred for headaches when not pregnant; and that the only safe OTC medication during pregnancy is Tylenol^® (acetaminophen).

Discussion

Key findings of our study include a high prevalence of OTC medication use during pregnancy of 87.5%, an association between OTC medication use in the 1–2 months before conception and prenatal use, and the initiation of OTC medications in pregnancy in 18% of women.

The high level of OTC medication use in our study compared to others may partly reflect our contemporary data. In a study in Aberdeen, the United Kingdom, the overall prenatal OTC medication use was 29.1% from 1985 to 2015, and increased to greater than 60% in the last seven years of the study. ¹⁷ A US study of controls from a case–control study of infants born 1981–1987 reported that non-prescription prenatal medication use was 1.5 times higher than prescription medical use. ⁴ Rates of OTC medication use, excluding vitamins and minerals, were 88% before conception, 71% in the first trimester, and 79% in the third trimester at a US academic hospital in 1995. ¹³ Similarly, in a single-center study in Michigan, 62.8% of pregnant women used OTC medications. ⁵ The prevalence of prenatal OTC medication use was 66.9% in a large cross-sectional study of women in Europe, North and South America, and Australia in 2011 to 2012. ⁸ Lower levels of use have been reported in hospital pregnancies in Dublin, Ireland from 2000 to 2007 (19.5%), ¹⁸ in a cross-sectional study in the United Arab Emirates (28%), ⁹ and a survey of women in low-income countries (30%). ¹⁰ Pregnant women in rural Virginia had a high prevalence (92.6%) of OTC medication use, ¹² as observed in our study population, 36% of whom lived in rural areas. The wide range of reported prevalence estimates also may reflect differences in practices and healthcare systems. ¹⁹

Like other studies,^3,9,12,20 acetaminophen was the most commonly used prenatal OTC medication—72.2% of women in our study—followed aspirin and ibuprofen. Early data from the US showed that two-thirds of women took acetaminophen during pregnancy and approximately 1 in 6 took a decongestant or ibuprofen, ³ and a recent US study reported acetaminophen, ibuprofen, docusate, pseudoephedrine, aspirin, and naproxen were most common. ²¹ Herbal medication use in 45.2% of rural pregnant patients ¹² and 4.1% of pregnant patients from an academic hospital also have been reported. ⁵ No women in our study reported herbal medication use.

Most obstetricians consider OTC medicines to be safe in pregnancy because of their low dose with very short-term use. ² While acetaminophen is generally considered the safest analgesic in pregnancy, some but not all studies have suggested a small risk of asthma, autism spectrum disorder, neurodevelopmental problems, attention-deficit/hyperactivity disorder, and behavioral problems in exposed fetuses. ²² Likewise, non-steroidal anti-inflammatory drugs such as ibuprofen and aspirin generally appear safe during the first and second trimesters, but third trimester exposure has been associated with fetal heart anomalies, low levels of amniotic fluid, and fetal kidney damage.^23,24 A higher risk of asthma in infants prenatally exposed to ibuprofen has been reported, ²⁵ and there are discrepant findings on the risk of hypospadias from ibuprofen exposure. ¹⁴ It is possible that the combined effect of ingredients also might potentiate a harmful effect. ² A systematic review reported a prevalence of polypharmacy including OTC medications ranging from 4.9% to 38.3%, ²⁶ and an early study of women in Connecticut identified that women who use prescription medications were more likely to use OTC. ²⁷ Significant evidence gaps exist in understanding the teratogenic risk of the vast majority of medications used in early pregnancy, ²¹ particularly in combination.

Pregnancy is often accompanied by symptoms for which OTC medications are used or recommended. Indeed, in our study, 18% of women initiated OTC medications in pregnancy, suggests a new indication for treatment. A qualitative study of women’s experiences of antenatal medication use in the United Kingdom found that many pregnant women wished to reduce exposure to OTC and prescribed medications, but dietary supplements and vaccines were generally accepted. ¹⁵ Almost all women in our study reported that not all OTC medications are safe to use during pregnancy, yet most used at least one. Some data also suggest that pregnant women’s awareness of the risks associated with use of medication have decreased, and some pregnant women consider medications harmless.^8,20

Strengths of our study include the recruitment of patients from an obstetrics clinic with a large catchment area, and a study sample that was representative of the underlying pregnant population. Limitations include low power to detect statistically significant differences in OTC medication use by demographic and cultural factors; these factors should be further examined in a larger Canadian study. In addition, we did not have information on physician recommendations regarding OTC medication use, dose, and frequency.

Conclusion

In conclusion, these new data suggest a high prevalence of OTC use in a pregnant population in Canadian. Women who used OTC medications in the 1–2 months prior to conception were more likely to use OTC medications prenatally, and approximately 2 in 10 women in our study initiated OTC medications in pregnancy. Further research on the risk of OTC medications and combinations in pregnancy is needed to help women to make informed choices during pregnancy.

Supplemental Material

Acknowledgments

Footnotes

References