Date Published: March 6, 2019
Publisher: Public Library of Science
Author(s): Christine Leong, Dan Chateau, Matthew Dahl, Jamie Falk, Alan Katz, Shawn Bugden, Colette Raymond, Barbara Mintzes.
We aimed to describe medication use in pregnancies that resulted in births and abortions, as well as use after a pregnancy-related visit to characterize the receipt of medication after knowledge of pregnancy. Abortions included both spontaneous and induced abortions. Rates of medication use among women with a pregnancy outcome (2001–2013) were described using the Manitoba Population Research Data Repository at the Manitoba Centre for Health Policy. Use was determined as ≥ 1 prescription filled during pregnancies that resulted in births (livebirth/stillbirth) and abortions. Rates were calculated at any time during pregnancy and after a pregnancy-related visit. Rates were additionally characterized by risk in pregnancy using Briggs classification (2017). Of 174,848 birth pregnancies, overall 64.9% filled ≥ 1 prescription during pregnancy (a significant increase from 62.3% to 68.8% from 2001–2013, p<0.0001); 55.4% filled ≥ 1 prescription after a pregnancy-related visit. Of 71,967 abortions, 44.7% filled ≥ 1 prescription (a significant increase from 42.6% to 46.8% from 2001–2013, p<0.0001). Only 3.7% of birth pregnancies had at least one prescription for a contraindicated medication (according to Briggs classification), whereas 10.8% of abortions filled a prescription for a contraindicated medication. The most common drugs used in pregnancy were amoxicillin, doxylamine, codeine combinations, nitrofurantoin, cephalexin, salbutamol and ranitidine. Fewer women filled prescriptions for undesirable medications according to Briggs classification during pregnancy after a pregnancy-related visit.
Drug prescribing in pregnancy remains a complex and controversial issue for pregnant women and clinicians [1–3]. As the availability and use of medications change over time, understanding the real world use of prescription medications during pregnancy is imperative to assessing exposure and risk at a population level .
This study was approved by the University of Manitoba Human Research Ethics Board.
There were a total of 174,848 (70.8%) birth pregnancies between 2001 and 2013, of which, 173,680 (99.3%) resulted in a livebirth and 1,168 (0.7%) resulted in a stillbirth. The mean gestational age for birth pregnancies was 38.93 weeks (SD 2.24 weeks). There were 71,969 (29.2%) abortions that were identified, in which a gestational age was available from health records (i.e., hospital, physician claims, and pregnancy-related visits) for 15,766 (21.9%). The gestational age was estimated to be eight weeks for the remaining pregnancies that resulted in abortion 56,201 (78.1%). The mean gestational age for abortions was 8.56 weeks (SD 2.21 weeks), which includes the eight-week imputed estimate. Table 1 describes the characteristics of the study population. A higher proportion of women under 25 years and over 40 years of age had a pregnancy resulting in an abortion compared to women with a pregnancy resulting in birth (43.0% vs. 30.2% and 4.6% vs. 2.2%, respectively). A higher proportion of women with a pregnancy resulting in an abortion resided in the lowest income quintile neighborhood compared to the proportion of women with a pregnancy resulting in a livebirth (29.4% vs. 26.3%).
We found an increase in the proportion of pregnancies involving at least one medication from 2001 to 2013, with a higher proportion of pregnancies resulting in abortion exposed to a medication considered “Contraindicated” compared to pregnancies resulting in birth. We also observed a drop in the receipt of undesirable medication among birth pregnancies after a pregnancy-related health visit, which may indicate a decrease in the intentional use of medication in pregnancy.
There was an increase in the proportion of pregnancies involving at least one medication from 2001 to 2013. Few women fill prescriptions for medications undesirable during pregnancy after a pregnancy-related visit. Contraindicated medications in pregnancy were dispensed to a higher proportion of pregnancies resulting in abortion compared to pregnancies resulting in a birth. We observed a drop in the receipt of medication among birth pregnancies after a pregnancy-related health visit. When describing intentional use of medication during pregnancy, it is important to consider prescriptions filled after the first pregnancy-related visit.