Screening of substance use in pregnancy: A Danish cross-sectional study

Abstract

Introduction: There is a paucity of objectively verified data on substance use among Danish pregnant women. We estimated the prevalence of substance use including alcohol and nicotine among the general population of Danish pregnant women.

Material and methods: In this anonymous, national, cross-sectional, descriptive study, pregnant women were invited when attending an ultrasound scan between November 2019 and December 2020 at nine Danish hospitals. Women submitted a urine sample and filled out a questionnaire. Urine samples were screened on-site with a qualitative urine dipstick for 15 substances including alcohol, nicotine, opioids, amphetamines, cannabis, and benzodiazepines. All screen-positive urine samples underwent secondary quantitative analyses with gold standard, liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Results were compared to questionnaire information to analyze the validity of self-reporting and to examine possible cross-reactions.

Results: A total of 1903 of 2154 invited pregnant women participated (88.3%). The prevalence of dipstick-positive urine samples was 25.0%. 44.0% of these were confirmed positive, resulting in a total confirmed prevalence of 10.8%. The prevalence of nicotine use was 10.1%-and for all other substances, <0.5%. Nicotine use was more prevalent among younger pregnant women, while other substance use appeared evenly distributed over age groups. Self-reporting of use of nicotine products was high (71.1%), but low for cannabis and alcohol intake (0% and 33.3%, respectively). Prescription medication explained almost all cases of oxycodone, methylphenidate, and benzodiazepine use.

Conclusions: Substance use among pregnant women consisted mainly of nicotine. Dipstick screening involved risks of false negatives and false positives. Except for alcohol intake and cannabis use, dipstick analyses did not seem to provide further information than self-reporting. LC-MS/MS analyses remain gold standard, and future role of dipstick screenings should be discussed.

Keywords: alcohol; cannabis; high risk pregnancy; maternal–fetal medicine; maternity care; neonatology; pregnancy; prenatal care; substance use.

FIGURE 1

Inclusion of participants. Inclusion of participants across the five regions of Denmark.

FIGURE 2

Validity of dipsticks. This graph provides a visual representation of relative percentages in relation to all dipstick‐positive samples (N=) for rates of confirmation and rates of self‐reported use of medications that can cause a false‐positive result (=cross‐react) on the dipstick based on an up‐to‐date list from the producer Ferle ApS (including self‐reported use of prescribed medications, vitamins/herbal remedies/dietary supplements, and over‐the‐counter).

FIGURE 3

Age and Confirmed Positive Samples. This visualization allows for a comparison of substance use patterns among pregnant women at different ages, stratified by confirmed cotinine use. Each individual blue dot represents a pregnant woman when age is given. In the graph, a red smoothing line descriptively shows the relation between age and the probability of a positive test. The left graph shows the age distribution of pregnant women with confirmed vs not confirmed positive cotinine samples, indicating tobacco/nicotine product use. The right graph shows the age distribution of pregnant women with confirmed vs not confirmed positive samples for substances other than cotinine.

FIGURE 4

Gestational Age and Confirmed Positive Samples. This visualization allows for a comparison of substance use patterns at different stages of pregnancy, stratified by cotinine use. Each individual blue dot represents a pregnant woman when age is given. In the graph, a red smoothing line descriptively shows the relation between gestational age and the probability of a positive test. The graph on the left shows the gestational age distribution of pregnant women with confirmed vs not confirmed positive cotinine samples, indicating tobacco/nicotine product use. The right graph shows the gestational age distribution of pregnant women with confirmed vs not confirmed positive samples for substances other than cotinine.

FIGURE 5

Distribution of substances across Denmark. (A) Total prevalences and prevalences of cotinine stratified by city. Please note that some urine samples were positive for two substances and both results are shown. (B) Distribution of substances among confirmed positive urine samples stratified by city (parts of whole). Please note that some urine samples were positive for two substances and both results are shown. (C) Zoom‐in on the total bar showing the distribution of substances except for cotinine. Please note that some urine samples were positive for two substances and both results are shown.

FIGURE 6

Validity of self‐reporting. This graph provides a visual representation of the percentages in relation to all confirmed positive samples for rates of self‐reported use of substances (tobacco/nicotine products, alcohol intake, and non‐prescribed use of amphetamines = red lines) and medications (prescribed medications, vitamins/herbal remedies/dietary supplements, and over‐the‐counter medications = blue lines). Zoom‐in on the substances with lower prevalences.