Inadequate birth spacing (less than 18 months between delivery and subsequent conception) is associated with low birth weight, preterm birth, and maternal complications.1 Women using highly effective contraception have nearly four times the odds of achieving adequate birth spacing than women using a barrier or no method.2 However, few U.S. women use long-acting reversible contraception (LARC; intrauterine devices [IUDs] and implants; 6%) or tubal sterilization (11%) by 3 months postpartum, partly as a result of poor access.3
Recent changes in practice guidelines and LARC reimbursement policies have created new opportunities for inpatient postpartum LARC provision.4,5 It is important to understand which groups use LARC and sterilization and in what delivery settings to ensure equitable access for women desiring these services.4,6 Moreover, reproductive justice advocates have highlighted the importance of avoiding coercion by balancing efforts to enhance access with efforts to prioritize patient autonomy.7 It is currently unknown whether inpatient postpartum LARC and sterilization use differs across patient groups or hospital types.
Our objective was to use the most recent nationally representative data to estimate changes in LARC insertion and tubal sterilization rates, identify correlates of their use during delivery hospitalizations, and compare characteristics across LARC and sterilization users. We hypothesized that LARC insertion would increase over time and be more likely among young women and those with medical comorbidities who might be particularly motivated to prevent recurrent pregnancy; those with nonprivate insurance who may have barriers to outpatient postpartum care; and those delivering at urban teaching hospitals where LARC expertise may concentrate.
MATERIALS AND METHODS
This retrospective cohort study used data from the National Inpatient Sample, the largest publicly available, all-payer, inpatient care database in the United States. The National Inpatient Sample was developed as part of the Healthcare Cost and Utilization Project of the Agency for Healthcare Research and Quality. The National Inpatient Sample is a stratified sample of 20% of hospital discharges from U.S. community hospitals (including academic medical centers and public hospitals) in 46 states. Using a self-weighting design, the National Inpatient Sample estimates more than 36 million hospitalizations annually and represents more than 95% of the U.S. population; full details about sampling and weighting procedures are available at the Healthcare Cost and Utilization website.8 The National Inpatient Sample has been used to generate national estimates of health care utilization since 1988 and specifically within the field of obstetrics, which has allowed for identification of delivery hospitalizations.9,10
The National Inpatient Sample contains clinical and nonclinical data for each hospitalization, including diagnostic and procedure codes, patient demographic characteristics, expected payment source, total charges, length of stay, and comorbidity measures. The National Inpatient Sample also contains data on hospital characteristics from the American Hospital Association Annual Hospital Survey, including hospital geographic region (Northeast, Midwest, South, and West), location (urban or rural), and teaching status (teaching or nonteaching; only reported for urban sites).
We generated a sample of delivery-related discharge records by identifying records with at least one Diagnosis-Related Group code for vaginal birth or cesarean delivery or International Classification of Diseases, 9th revision, Clinical Modification (ICD-9-CM) diagnosis or procedure code for delivery in all of the study years. Tubal sterilizations were identified by the presence of ICD-9-CM diagnosis code V25.2 in addition to ICD-9-CM procedure codes 65.6, 66.5, 66.63, or 66.97 or ICD-9-CM procedure code 66.2–66.3 alone. We excluded records if they contained codes for both IUD insertion and tubal sterilization or implant insertion and tubal sterilization (n=68). Although other investigators have also excluded cases with coincident hysterectomy codes,9 we elected to retain these cases (n=398 tubal+hysterectomy; n=1 LARC+hysterectomy) given our focus on access to inpatient postpartum contraception.
Comorbidities were identified using the Healthcare Cost and Utilization Project's comorbidity flags, which use the Elixhauser comorbidity measures to identify anemia, cancer, chronic lung disease, coagulation disorders, diabetes mellitus, heart disease, human immunodeficiency virus or acquired immunodeficiency syndrome, hypertension, hypothyroidism, liver disorders, obesity, neurologic disorders, renal failure, and rheumatoid arthritis or collagen vascular diseases.11 Teaching status is reported only for urban hospitals. We combined location and teaching status to create a hospital type variable (urban teaching, urban nonteaching, rural). The unit of analysis is the discharge record, because the National Inpatient Sample does not include any patient identifiers. Although possible that some women underwent more than one inpatient postpartum contraceptive procedure during the 5-year study period and are reflected in more than one record, we assume that this is exceedingly rare and that each case in the National Inpatient Sample therefore represents one unique woman.
Statistical analyses were performed using the survey analysis procedures in SAS. All analyses were conducted using Agency for Healthcare Research and Quality-specified discharge weights to obtain nationally representative estimates. All reported estimates are based on at least 35 unweighted cases and are weighted estimates, unless otherwise noted. The National Inpatient Sample sampling design changed in 2012; for many estimates, the confidence intervals (CIs) are approximately half the length of CIs under the previous design.8 We calculated a national estimate for total number of delivery hospitalizations. We calculated rates (count per 10,000 deliveries) of inpatient postpartum LARC insertion, IUD insertion, implant insertion, and tubal sterilization using Wald χ2 test. We performed simple logistic regression of each outcome with time as a predictor to assess for linear trends across the study period. To minimize imprecision resulting from small numbers of unweighted cases for LARC insertion, years for trend analyses were combined into 2-year intervals. We calculated the rates±standard error of inpatient postpartum LARC insertion and tubal sterilization across subgroups. We then built a multivariable logistic regression model with a three-level nominal outcome (LARC, tubal sterilization, or neither) to estimate adjusted odds ratios (ORs) and 95% CIs using the “neither” group as the referent. We also used a separate multivariable logistic regression model to compare the characteristics of LARC and tubal sterilization users. Each multivariable model controlled for patient age, delivery mode, presence of any medical comorbidity, primary payer, hospital type, geographic region, and year. Statistical significance was defined as P<.05. Because this study involved only the analysis of deidentified national data, it was deemed not regulated for human subject review by the University of Michigan Medical School institutional review board.
There were 4,691,683 unweighted delivery discharges in the 2008–2013 National Inpatient Sample, representing approximately 22,667,204 deliveries in the United States (compared with approximately 24 million total U.S. births during the study period). An estimated 1,613,340 women received either LARC (n=18,206) or tubal sterilization (n=1,595,134) during their delivery hospitalization. The LARC insertion rate increased from 1.86 per 10,000 deliveries in 2008–2009 to 13.5 per 10,000 deliveries in 2012–2013 (P<.001; Fig. 1) driven by significant increases in both IUD and implant use. The tubal sterilization rate did not change significantly during the study period (711/10,000 deliveries, 2008–2009; 683/10,000 deliveries, 2012–2013; P=.24). Variation in reported CIs may be the result of the data set's 2012 design change.8
Long-acting reversible contraception use was highest among woman with medical comorbidities, with a nonprivate payer, in urban teaching sites, in the West, and in later study years (Table 1). Sterilization rates were highest among women 35 years or older and those undergoing cesarean delivery. In a multivariable model controlling for patient demographics, hospital characteristics, and year, and comparing with neither LARC nor sterilization, LARC insertion was significantly associated with all variables except patient age. Independent variables strongly associated with LARC use included payer, hospital type, and study year. Women with a nonprivate payer were five times as likely as those with a private payer to receive LARC (adjusted OR 5.23, 95% CI 3.82–7.16). Women delivering at urban teaching hospitals were 20 times as likely to receive these devices (adjusted OR 20.85, 95% CI 12.73–34.15) as women delivering at rural hospitals. Compared with 2008–2009, the odds of LARC insertion increased in later years of the study period (2010–2011: adjusted OR 3.93, 95% CI 1.72–9.00; 2012–2013: adjusted OR 6.49, 95% CI 3.53–11.94). Long-acting reversible contraception use was also more likely with cesarean compared with vaginal delivery (adjusted OR 1.36, 95% CI 1.11–1.68) and presence of any medical comorbidity compared with none (adjusted OR 1.92, 95% CI 1.72–2.13) and less likely among women receiving care in the Midwest (adjusted OR 0.17, 95% CI 0.10–0.29) or the South (adjusted OR 0.38, 95% CI 0.18–0.78) compared with the West.
Conversely, tubal sterilization was independently associated with patient age and delivery mode (Table 1). Younger women were less likely than those 35 years or older to undergo sterilization (adjusted ORs 0.12–0.61), and those undergoing cesarean compared with vaginal delivery were more likely to undergo sterilization (adjusted OR 6.25, 95% CI 5.88–6.63). Medical comorbidity (adjusted OR 1.17, 95% CI 1.14–1.20), nonprivate payer (adjusted OR 2.20, 95% CI 2.10–2.30), and delivery in the South (adjusted OR 1.39, 95% CI 1.27–1.52) also increased odds of tubal sterilization. Odds of tubal sterilization were significantly lower at urban compared with rural hospitals (urban nonteaching: adjusted OR 0.59, 95% CI 0.55–0.63; urban teaching: adjusted OR 0.56, 95% CI 0.51–0.62), in the Northeast compared with the West (adjusted OR 0.83, 95% CI 0.76–0.91), and in later years of the study period compared with 2008–2009 (2010–2011: adjusted OR 0.93, 95% CI 0.88–0.99; 2012–2013: adjusted OR 0.88, 95% CI 0.83–0.95).
We observed significant differences in patient and hospital characteristics among women receiving LARC compared with tubal sterilization (Table 2). Compared with sterilization users, greater proportions of LARC users were women younger than 24 years (46.76% compared with 11.70%) and delivering vaginally (64.15% compared with 25.30%) with a nonprivate payer (84.95% compared with 57.17%). Urban teaching hospitals inserted nearly all LARC devices (94.65%), whereas tubal sterilizations were more evenly distributed across hospital types. Proportionally more LARC devices were placed in later study years (2010–2011, 36.08%; 2012–2013, 55.72%), whereas sterilization was evenly distributed across the study period.
In a multivariable model adjusting for patient and hospital characteristics and year, LARC use continued to be associated with patient age, delivery mode, medical comorbidity, payer, hospital type, geographic region, and year. Women younger than 24 years were 12 times more likely to receive LARC than tubal sterilization (adjusted OR 12.62, 95% CI 9.59–16.61), although many more young women received tubal sterilization than LARC (186,633 compared with 8,513). Women with medical comorbidity (adjusted OR 1.49, 95% CI 1.31–1.70), a nonprivate payer (adjusted OR 1.90, 95% CI 1.38–2.63), delivery at urban teaching hospitals (adjusted OR 38.39, 95% CI 23.52–62.64, compared with rural sites), and delivery later in the study period (2010–2011: adjusted OR 4.51, 95% CI 1.98–10.24; 2012–2013: adjusted OR 8.26, 95% CI 4.42–15.44, compared with 2008–2009) were more likely to receive LARC than tubal sterilization. Long-acting reversible contraception insertion was significantly less likely with cesarean delivery (adjusted OR 0.23, 95% CI 0.19–0.29) and delivery in the Midwest (adjusted OR 0.15, 95% CI 0.09–0.26) and the South (adjusted OR 0.25, 95% CI 0.12–0.52, compared with the West).
This study had three principal findings. First, LARC insertion rates during U.S. delivery hospitalizations increased sevenfold from 2008 to 2013, whereas tubal sterilization rates remained stable. Second, LARC insertion occurred almost exclusively at urban teaching hospitals (94.65%) and most commonly involved women with nonprivate payers (84.95%). Third, LARC users and sterilization users were demographically distinct; LARC users tended to be younger, with a medical comorbidity, delivering vaginally, and in the West.
Our findings build on prior work examining national inpatient postpartum IUD and sterilization rates from 2001 to 2008.9 We demonstrate continued increases in LARC use and stronger associations between LARC use and patient and hospital characteristics.
In our study, tubal sterilization occurred much more frequently than LARC placement during delivery hospitalizations. An estimated 1,595,134 women underwent sterilization compared with only 18,206 receiving LARC. These estimates, observed variation across hospital type and geographic region, and prior work identifying unmet demand for LARC after childbirth together suggest access barriers to inpatient LARC.12 Urban nonteaching and rural hospitals may face institutional barriers to providing inpatient LARC services, including challenges regarding health care provider training, device supply chain, and billing and reimbursement.13–15 Clinicians seeking to offer inpatient LARC may benefit from publicly available resources, including an implementation guide and health care provider training materials.16,17
Primary payer may influence postpartum contraceptive use. Women with nonprivate insurance were much more likely to receive LARC or tubal sterilization compared with those receiving neither. Other recent studies suggest that female sterilization varies by payer, but LARC use does not.9,18–21 Our findings could represent patient preferences; many Medicaid beneficiaries lose coverage 60 days postdelivery and may be particularly motivated to initiate highly effective contraception before hospital discharge. Alternatively, findings could result from biased counseling and care with clinicians disproportionately promoting LARC and sterilization to women with nonprivate insurance. Women with nonprivate insurance had 1.9 times the odds of LARC insertion compared with sterilization. Medicaid policy requiring signed consent 30 days in advance may limit use of sterilization.22,23 Additionally, covered benefits and reimbursement rates may differ between private and nonprivate plans and drive differences in LARC availability and use. Findings predate recent changes in Medicaid reimbursement for inpatient postpartum LARC, but variation in coverage across states may affect future utilization trends.5,24
Inpatient postpartum LARC use concentrated among certain demographic groups. A significantly higher proportion of LARC compared with sterilization users were aged younger than 30 years. This is reassuring given the known association between age younger than 30 years and risk of regret with sterilization.25 However, the estimated number of women younger than 30 years receiving tubal sterilization (n=616,781) still vastly outstripped those receiving LARC (n=12,969) during 2008–2013. Inpatient postpartum LARC insertion is safe and effective for adolescents and young women and is likely underused by this population.
Women with medical comorbidities were also more likely to use LARC or sterilization, possibly as a result of motivation to avoid high-risk pregnancy. These women accounted for higher proportions of LARC compared with sterilization users. Women with medical comorbidities and their health care providers may perceive LARC as particularly advantageous, because it has few medical contraindications and provides equivalent contraceptive effectiveness while avoiding potential risks of sterilization surgery.4
Our findings should be interpreted in light of limitations common to studies using nationally representative discharge data. These data rely on accurate coding, and errors of commission or omission may occur. Claims data may not accurately capture every LARC device inserted, especially because these claims have not traditionally generated a payment separate from bundled fees for delivery care. As a surgical procedure, tubal sterilization may be less likely to be undercaptured. Our data set is unable to ascertain whether increased LARC use results from decreased reliance on sterilization or other contraceptive methods, a shift in LARC insertion from the outpatient to the inpatient setting, or increased LARC uptake by prior nonusers of contraception. The National Inpatient Sample is designed to permit analyses of a nationally representative sample of all hospitalization discharge records, not delivery hospitalization discharge records; however, prior work suggests full capture of hospital-based births.10 Finally, although race is a known predictor of our outcomes, we could not include it in our models as a result of incomplete data in the National Inpatient Sample.26
Despite these limitations, our study provides the most recent national estimates of inpatient postpartum LARC insertion and tubal sterilization. Observed variation in these procedures across hospital type, region, and primary payer suggests possible access barriers to these services. Improving contraceptive access is the focus of ongoing national efforts to monitor LARC and sterilization use after childbirth.27 Women who are unable to initiate their preferred contraceptive method after childbirth are at increased risk of unintended short-interval pregnancy.28,29 Maternity clinicians and policymakers should strive to ensure that women have access to the full contraceptive method mix after childbirth and can make an informed, voluntary, personal choice about whether and when to have another child.
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