Prevalence of Pregnancy in Drug Overdose Presenting to a Tertiary Toxicology Service

Introduction: Poisoning in pregnant women creates challenges to healthcare providers due to the potential for dual harm to the mother and fetus from the exposure. The unknown safety profile of antidotes in pregnancy and nature of supportive care for pregnant women further complicate this presentation. Within the ED, the prevalence of unexpected pregnancy is shown to be between 0.2 and 6.3% for all presentations, whilst studies specific to poisonings demonstrate a prevalence of 0.07– 0.6%. Materials and Methods: The Western Sydney Toxicology Service (WSTS) works in the Western Sydney Local Health District to provide specialist poisons care to patients. We conducted a retrospective cohort study of all women who presented to the ED in Western Sydney hospitals requiring specialist toxicology advice or admission between ages 14 and 50 years. Primary outcome was the rate of pregnancy, especially unexpected pregnancy, between Jan 2013 and Nov 2019. Secondary outcomes included determining compliance with department policy of blood β-HCG testing for all female patients in reproductive years, rates of polypharmacy ingestions, types of exposures and drug classes commonly associated with poisoning. Results: Overall: The pregnancy rate was 1.6% (n = 39), while the unexpected pregnancy rate was 0.78% (n = 19). About 99.3% (n = 2421) had a blood test taken in ED or day one of admission, with 65.8% (n = 1605) having a blood β-HCG level measured. There was a higher proportion of deliberate self-poisonings (72.6%, n = 1771) compared to other exposures. Single drug exposures occurred in 58.9% (n = 1436). There was a mean of 1.56 drug class exposures per patient (n = 3795), with paracetamol being the most common (26.9%, n = 656). Discussion and Conclusion: There was a low rate of pregnancy, especially unexpected pregnancy, in keeping with studies in the poisoned population. We noted moderate compliance with our department policy of blood β-HCG measurement and determined that most exposures were deliberate self-poisonings, with over a quarter involving paracetamol.