Objective
The purpose of this study was to estimate US rates of postpartum intrauterine device (IUD) insertion and postpartum tubal sterilization.
Study Design
Data from the 2001-2008 Nationwide Inpatient Sample were used to identify delivery hospitalizations with IUD insertion or tubal sterilization procedure codes.
Results
Estimated rates of postpartum IUD insertion and postpartum tubal sterilization were 0.27 and 770.67 per 10,000 deliveries, respectively. Although the rate of IUD insertion was similar across age groups, the rate of tubal sterilization increased with age. Nonetheless, 15% of tubal sterilizations occurred among women who were ≤24 years old. IUD insertion was more likely among women who delivered at teaching hospitals (odds ratio, 3.02; 95% confidence interval, 1.43–6.37); tubal sterilization was more likely among women without private insurance (odds ratio, 2.04; 95% confidence interval, 1.97–2.11).
Conclusion
Among US postpartum women, IUD insertion occurs considerably less frequently than tubal sterilization, even among younger women for whom poststerilization regret is a concern.
Use of effective contraception in the postpartum period is an essential strategy to both prevent unintended pregnancies and ensure optimal birth spacing. Nonetheless, among women who were surveyed at 2-9 months after delivery in 12 states and New York City from 2004-2006, only 62% of the women reported using effective contraceptive methods, with failure rates of <10% under typical use (hormonal methods, male or female sterilization, or intrauterine devices [IUDs]). The initiation of contraception before hospital discharge after delivery is a potentially practical and cost-effective strategy to increase effective postpartum contraceptive use, given that the women are already within the health care system and motivation for contraception may be high.
Tubal sterilization and both types of IUDs that are available in the United States (the copper IUD and the levonorgestrel-releasing IUD) are all highly effective contraceptive methods that may be initiated safely in the immediate postpartum period before hospital discharge, regardless of breastfeeding status. IUDs are similar to tubal sterilization in their effectiveness but are also easily reversible. IUDs can be inserted any time in the postpartum period; immediate postplacental insertion is associated with lower expulsion rates than delayed postpartum insertion (up to 72 hours after delivery) but is associated with slightly higher expulsion rates than interval insertion (unrelated to pregnancy).
Among all US women of reproductive age, usage of the IUD has increased but remains low; it was used by 2% of contraceptive users in 2002 and by 5.5% in 2006-2008. To date, little information exists regarding the rate of postpartum IUD insertion or factors that are associated with undergoing the procedure in the United States. Additionally, recent information regarding postpartum tubal sterilization is limited. The objectives of our study were to estimate national rates of postpartum IUD insertion and tubal sterilization procedures and to describe recent trends in these rates, to examine whether maternal or hospital characteristics are associated with the likelihood of undergoing these procedures, and to compare the characteristics of women who undergo postpartum IUD insertion with those who undergo postpartum sterilization. This information will provide baseline rates to monitor future trends and may facilitate the development of targeted interventions or programs to increase the use of effective postpartum contraception that may be provided during delivery hospitalization.
Materials and Methods
We used data from the Nationwide Inpatient Sample (NIS) of the Healthcare Cost and Utilization Project (HCUP) for 2001–2008. The Healthcare Cost and Utilization Project is a family of health care databases developed through a federal-state-industry partnership sponsored by the Agency for Healthcare Research and Quality in which state partners contribute data. The NIS is the largest all-payer inpatient care database in the United States and contains data on 7-8 million hospital stays from approximately 1000 hospitals per year from 2001-2008, which approximates a 20% stratified sample of US hospitals. The sampling frame for the NIS changes annually; in 2001 the NIS included 33 states and in 2008 the NIS included 42 states. Each record includes a discharge weight to account for these differences and to allow for national estimates.
The design of the NIS is described in detail elsewhere. Briefly, the NIS is a stratified probability sample of community hospitals in the United States that is based on a sampling frame using 5 strata: geographic region (Northeast, Midwest, West, and South), hospital size (based on number of beds), location (urban or rural), teaching status, and control (public, voluntary, or, proprietary). The universe of US community hospitals includes all those hospitals that were open during any part of the calendar year and were designated as community hospitals in the American Hospital Association Annual Survey of Hospitals. The American Hospital Association defines community hospitals as all nonfederal short-term (average length of stay <30 days) general and specialty hospitals that are accessible by the general public. Data are retained for 100% of discharges for each sampled hospital. In the NIS, inpatient-stay records include information on patient characteristics, medical diagnoses, and surgical procedures. The NIS also contains hospital-level data from the American Hospital Association Annual Survey of Hospitals, which includes hospital geographic region, location, and hospital teaching status.
We restricted our analysis to delivery-related discharge records that were identified with the use of the Diagnosis-Related Groups codes for vaginal birth and for cesarean delivery or International Classification of Diseases , ninth revision, Clinical Modification (ICD-9-CM) procedure codes for cesarean delivery. IUD insertions were identified by the presence of ICD-9-CM diagnosis code V25.1 or ICD-9-CM procedure code 69.7. Tubal sterilizations were identified by the presence of ICD-9-CM procedure codes 66.2-66.3 or ICD-9-CM diagnosis code V25.2 in conjunction with ICD-9-CM procedure codes 65.6, 66.5, 66.63, or 66.97. We excluded records if they contained codes for hysterectomy or if they contained codes for both IUD insertion and tubal sterilization; the excluded records comprised <1% of all delivery-related discharge records. Discharge records with comorbidities were identified by the Healthcare Cost and Utilization Project’s Comorbidity Software; comorbidities that were considered included heart disease, hypertension, diabetes mellitus, HIV/AIDS, chronic lung disease, thyroid disorders, cancer, obesity, anemia, neurologic disorders, renal failure, liver disorders, rheumatoid arthritis/collagen vascular diseases, and coagulation disorders. Because there is no patient identifier in the NIS, the unit of analysis typically is considered to be the hospital discharge record because a patient can be admitted multiple times. However, because this analysis involved long-acting and permanent methods of contraception, we assume that each hospitalization represents 1 woman. Nonetheless, it is possible that some women underwent >1 postpartum procedure (eg, IUD insertion and tubal sterilization) that was associated with different deliveries during the 8-year study period.
SAS–callable SUDAAN software (version 9.2; Research Triangle Institute, Research Triangle Park, NC) was used to account for the complex sampling design in the NIS. Rates of postpartum IUD insertion and tubal sterilization were calculated per 10,000 deliveries. We considered estimates to be reportable if they were based on >10 unweighted cases and had a relative standard error <30%. To obtain reportable estimates for postpartum IUD insertions, years for all trend analyses were combined into 2-year intervals. We used the SUDAAN procedure PROC RATIO to test for linear and quadratic trends in rates over the study period. Trends in postpartum tubal sterilization rates were assessed overall and within subgroups of interest that were defined by age, geographic region, and delivery mode. The small number of postpartum IUD insertions was insufficient to examine trends in rates within subgroups. Race was not examined because a large proportion of records did not have race information.
We used the SUDAAN procedure PROC MULTILOG to construct a polytomous logistic regression model using data for 2001-2008 to assess factors that were associated with postpartum IUD insertion or postpartum tubal sterilization vs neither procedure. A 3-level nominal outcome was used in the model (postpartum IUD insertion, postpartum tubal sterilization, and neither postpartum IUD insertion nor tubal sterilization [Referent]) to estimate odds ratios (ORs) and 95% confidence intervals (CIs). A separate logistic regression model was constructed to compare the characteristics of women who underwent postpartum IUD insertion with those of women who underwent postpartum tubal sterilization. Because the NIS data are publicly available and do not contain personal identifiers, the Centers for Disease Control and Prevention determined that this project did not require human subject research review.
Results
During 2001-2008, the estimated rate of IUD insertions that were performed during delivery hospitalizations in the United States was 0.27 per 10,000 deliveries; by contrast, the rate of postpartum tubal sterilization was 770.67 per 10,000 deliveries. The rate of postpartum IUD insertion increased linearly from 0.10 per 10,000 deliveries in 2001-2002 to 0.55 per 10,000 deliveries in 2007-2008 ( P for trend, < .001; Figure ). A quadratic trend was detected in the rate of postpartum tubal sterilization over the time period ( P for trend, < .01); the rate increased from 753.95 per 10,000 deliveries in 2001-2002 to 804.40 per 10,000 deliveries in 2005-2006 and then decreased to 743.58 per 10,000 deliveries in 2007-2008.
