Pregnancy with retained intrauterine device: national-level assessment of characteristics and outcomes

BACKGROUND Although intrauterine devices provide effective contraceptive protection, unintentional pregnancy can occur. Previous studies have shown that a retained intrauterine device during pregnancy is associated with adverse pregnancy outcomes but there is a paucity of nationwide data and analysis. OBJECTIVE This study aimed to describe characteristics and outcomes of pregnancies with a retained intrauterine device. STUDY DESIGN This serial cross-sectional study used data from the Healthcare Cost and Utilization Project's National Inpatient Sample. The study population comprised 18,067,310 hospital deliveries for national estimates from January 2016 to December 2020. The exposure was retained intrauterine device status, identified by the World Health Organization's International Classification of Diseases, Tenth Revision, code O26.3. The co-primary outcome measures were incidence rate, clinical and pregnancy characteristics, and delivery outcome of patients with a retained intrauterine device. To assess the pregnancy characteristics and delivery outcomes, an inverse probability of treatment weighting cohort was created to mitigate the prepregnant confounders for a retain intrauterine device. RESULTS A retained intrauterine device was reported in 1 in 8307 hospital deliveries (12.0 per 100,000). In a multivariable analysis, Hispanic individuals, grand multiparity, obesity, alcohol use, and a previous uterine scar were patient characteristics associated with a retained intrauterine device (all P<.05). Current pregnancy characteristics associated with a retained intrauterine device included preterm premature rupture of membrane (9.2% vs 2.7%; adjusted odds ratio, 3.15; 95% confidence interval, 2.41–4.12), fetal malpresentation (10.9% vs 7.2%; adjusted odds ratio, 1.47; 95% confidence interval, 1.15–1.88), fetal anomaly (2.2% vs 1.1%; adjusted odds ratio, 1.71; 95% confidence interval, 1.03–2.85), intrauterine fetal demise (2.6% vs 0.8%; adjusted odds ratio, 2.21; 95% confidence interval, 1.37–3.57), placenta malformation (1.8% vs 0.8%; adjusted odds ratio, 2.12; 95% confidence interval, 1.20–3.76), placenta abruption (4.7% vs 1.1%; adjusted odds ratio, 3.24; 95% confidence interval, 2.25–4.66), and placenta accreta spectrum (0.7% vs 0.1%; adjusted odds ratio, 4.82; 95% confidence interval, 1.99–11.65). Delivery characteristics associated with a retained intrauterine device included previable loss at <22 weeks’ gestation (3.4% vs 0.3%; adjusted odds ratio, 5.49; 95% confidence interval, 3.30–9.15) and periviable delivery at 22 to 25 weeks’ gestation (3.1% vs 0.5%; adjusted odds ratio, 2.81; 95% confidence interval, 1.63–4.86). Patients in the retained intrauterine device group were more likely to have a diagnosis of retained placenta at delivery (2.5% vs 0.4%; adjusted odds ratio, 4.45; 95% confidence interval, 2.70–7.36) and to undergo manual placental removal (3.2% vs 0.6%; adjusted odds ratio, 4.81; 95% confidence interval, 3.11–7.44). CONCLUSION This nationwide analysis confirmed that pregnancy with a retained intrauterine device is uncommon, but these pregnancies may be associated with high-risk pregnancy characteristics and outcomes. Although intrauterine devices provide effective contraceptive protection, unintentional pregnancy can occur. Previous studies have shown that a retained intrauterine device during pregnancy is associated with adverse pregnancy outcomes but there is a paucity of nationwide data and analysis. This study aimed to describe characteristics and outcomes of pregnancies with a retained intrauterine device. This serial cross-sectional study used data from the Healthcare Cost and Utilization Project's National Inpatient Sample. The study population comprised 18,067,310 hospital deliveries for national estimates from January 2016 to December 2020. The exposure was retained intrauterine device status, identified by the World Health Organization's International Classification of Diseases, Tenth Revision, code O26.3. The co-primary outcome measures were incidence rate, clinical and pregnancy characteristics, and delivery outcome of patients with a retained intrauterine device. To assess the pregnancy characteristics and delivery outcomes, an inverse probability of treatment weighting cohort was created to mitigate the prepregnant confounders for a retain intrauterine device. A retained intrauterine device was reported in 1 in 8307 hospital deliveries (12.0 per 100,000). In a multivariable analysis, Hispanic individuals, grand multiparity, obesity, alcohol use, and a previous uterine scar were patient characteristics associated with a retained intrauterine device (all P<.05). Current pregnancy characteristics associated with a retained intrauterine device included preterm premature rupture of membrane (9.2% vs 2.7%; adjusted odds ratio, 3.15; 95% confidence interval, 2.41–4.12), fetal malpresentation (10.9% vs 7.2%; adjusted odds ratio, 1.47; 95% confidence interval, 1.15–1.88), fetal anomaly (2.2% vs 1.1%; adjusted odds ratio, 1.71; 95% confidence interval, 1.03–2.85), intrauterine fetal demise (2.6% vs 0.8%; adjusted odds ratio, 2.21; 95% confidence interval, 1.37–3.57), placenta malformation (1.8% vs 0.8%; adjusted odds ratio, 2.12; 95% confidence interval, 1.20–3.76), placenta abruption (4.7% vs 1.1%; adjusted odds ratio, 3.24; 95% confidence interval, 2.25–4.66), and placenta accreta spectrum (0.7% vs 0.1%; adjusted odds ratio, 4.82; 95% confidence interval, 1.99–11.65). Delivery characteristics associated with a retained intrauterine device included previable loss at <22 weeks’ gestation (3.4% vs 0.3%; adjusted odds ratio, 5.49; 95% confidence interval, 3.30–9.15) and periviable delivery at 22 to 25 weeks’ gestation (3.1% vs 0.5%; adjusted odds ratio, 2.81; 95% confidence interval, 1.63–4.86). Patients in the retained intrauterine device group were more likely to have a diagnosis of retained placenta at delivery (2.5% vs 0.4%; adjusted odds ratio, 4.45; 95% confidence interval, 2.70–7.36) and to undergo manual placental removal (3.2% vs 0.6%; adjusted odds ratio, 4.81; 95% confidence interval, 3.11–7.44). This nationwide analysis confirmed that pregnancy with a retained intrauterine device is uncommon, but these pregnancies may be associated with high-risk pregnancy characteristics and outcomes.