Objective
The purpose of this study was to document cost that is associated with multiple births vs singleton births in the United States.
Study Design
This was a retrospective cohort study that used a claims database. Women 19-45 years old with live-born infants from 2005-2010 were identified. Infant deliveries were identified by International Classification of Diseases , 9th Revision, Clinical Modification diagnosis codes. The cost entailed all payment made by insurers and patients. For mothers, the cost included expenses from 27 weeks before delivery to 1 month after delivery. For infants, the cost contained all expenses until their first birthday. Adjusted cost was estimated by generalized linear models after adjustment for the potential confounding variables with a gamma distribution and a log link.
Results
The analysis included 437,924 eligible deliveries. Of them, 97.02% were singletons; 2.85% were twins, and 0.13% was triplets or more. Women with multiple pregnancies had higher systemic and localized comorbidities compared with women with singleton pregnancies ( P < .0001). Twins and triplets or more were more likely to have stayed in a neonatal intensive care unit than were singletons ( P < .0001). On average, adjusted total all-cause health care cost was $21,458 (95% confidence interval [CI], $21,302–21,614) per delivery with singletons, $104,831 (95% CI, $103,402–106,280) with twins, and $407,199 (95% CI, $384,984–430,695) with triplets or more.
Conclusion
Pregnancies with the delivery of twins cost approximately 5 times as much when compared with singleton pregnancies; pregnancies with delivery of triplets or more cost nearly 20 times as much.
For Editors’ Commentary, see Contents
Multiple pregnancies have been a major public health concern in the United States and the rest of the world because of the significantly high morbidity and mortality rates for both mothers and infants and increased health care cost. The prevalence of multiple pregnancies is increasing worldwide in parallel with increased use of assisted reproductive technology (ART). According to the Centers for Disease Control and Prevention, 3% of all infants born in the United States were multiple deliveries in 2010; the twin birth rate was 33.1 per 1000 total births, and the rate of triplets and higher-order multiple births was 1.4 per 1000 births. Accurate estimates of the relative proportions of multiple births that are attributable to ovulation induction or super ovulation and ART are difficult to determine, because ovulation induction/super ovulation cycles currently are not captured in a national registry. Nevertheless, there is consensus that most twin births result from natural conception (approximately 60%). For high-order multiple gestations, however, there is agreement that only approximately 20% result from natural conception.
There is a paucity of data in the literature that documents health care expenditures associated with multiple pregnancies. Callahan et al determined hospital charges and the use of ARTs in their hospital and showed that the total charges to the family in 1991 for a singleton delivery were $9845, compared with $37,947 for twins and $109,765 for triplets. Ettner et al investigated factors associated with high cost of multiple pregnancies and revealed that birthweight and gestational age accounted fully for the increased use of neonatal intensive care unit (NICU) services among multiples. Bromer et al modeled the financial burden of preterm birth in the United States as a consequence of ART use and estimated that total annual cost amounted to 1 billion US dollars. Although the cost associated with multiple pregnancies is expected to be significant, there has been no update in the literature on the economic impact of multiple pregnancies in the United States in recent years. The aim of our study was to document and compare cost that is associated with multiple pregnancies vs singleton pregnancies in the United States.
Materials and Methods
Data source
We investigated the cost that is associated with multiple vs singleton pregnancies by analyzing the MarketScan database (Truven Health Analytics Inc, Ann Arbor, MI), which is a commercial claims and encounters database. The database contains deidentified, member-specific health data that includes clinical use, costs, and enrollment across inpatient, outpatient, and prescription drugs. The data cover >20 million individuals with employer-sponsored benefits annually, including private sector claims data from approximately 100 payers and can be linked to track detailed patient information across geographic location, types of providers, and time.
Patients and study variable measurements
The source population included all women 19-45 years old who delivered at least 1 live-born infant; the delivery types were reported (singleton, twins, triplets or more) between Jan. 1, 2005, and Sept. 30, 2010. We included only women who had continuous enrollment for at least 1 year both before and after the delivery date. Deliveries of singletons, twins, and triplets or more were identified with the use of the International Classification of Diseases , 9th Revision, Clinical Modification (ICD-9-CM) diagnosis codes. The presence of comorbidities during pregnancy was tabulated based on ICD-9-CM diagnosis codes during the last 27 weeks of a pregnancy, which was expected to reflect the second and third trimesters of a full-term delivery. Comorbidities were categorized into systemic comorbidities and comorbidities localized to the reproductive tract. Systemic comorbidities included hypertension, cardiovascular disease, diabetes mellitus, edema/renal disease, genitourinary infection, thyroid disease and anemia; localized comorbidities included hemorrhage (placental abruption, placenta previa, other), chorioamnionitis, amniotic sac disorders (polyhydramnios, oligohydramnios, unspecified), cervical incompetence, and structural abnormality (uterus/cervix/vagina/vulva). Current Procedure Terminology codes in the previous 42 weeks’ gestation (294 days) before the delivery were used to determine whether a mother had received in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) for that pregnancy.
The cost entailed all payments made by insurers and patient out-of-pocket medical expenses, including all-cause payment for inpatient and outpatient services, and prescription drugs. For mothers, the cost included medical expenses during the 27 weeks before the delivery date and up to 30 days after the delivery date. For infants, the cost contained all medical expenses up to their first birthday. Infants were linked with their mother by the family identification number. In addition, their birth year must be the same as the year of the woman’s delivery date. Because we could not differentiate between siblings when a mother had >1 live-born delivery because of the database structure, costs for twins or triplets or more were summarized by each delivery. Costs were inflation-normalized to 2010 US dollars using the Consumer Price Index All Urban Consumers for medical care services in accordance with International Society for Pharmacoeconomics and Outcome Research recommendations for working with cost data.
Women’s age, plan type, and geographic region were based on the values recorded on the delivery date in the database. Plan type was reported by 4 categories: health maintenance organization, point of service, preferred provider organization, and other/unknown. Geographic region was reported as North Central, Northeast, South, West, and unknown. Institutional review board approval was not obtained because this study was an analysis of deidentified secondary data ( Appendix ; Supplementary Tables 1-4 ).
Data analysis
We first examined women’s baseline characteristics across delivery types (singleton, twins, triplets or more). For continuous variables, including age, analysis of variance was used. For categoric variables, including year of delivery, IVF/ICSI (yes/no), plan type and region, the Chi-square test was used. Presence of each comorbidity and clinical outcomes such as death, delivery type (vaginal vs cesarean delivery), and NICU stay were compared with the use of bivariate logistic regression for twins vs singletons and triplets or more vs singletons. Continuous clinical outcomes including mothers’ length of hospital stay and infants’ length of NICU stay were compared with the use of nonparametric Wilcoxon-sum-rank test because of nonnormal distribution.
Because health care expenses may vary by maternal age, year of the delivery, health care plan, and geographic region, we used generalized linear models to adjust for these variables with a gamma distribution and a log link. This approach resolves the issue of skewed cost distribution that is common in claims data. Further, it has been demonstrated that a generalized linear model can provide more robust coefficient estimates than logged ordinary least square regression, where the log transformation is often used to address skewed cost data. A negative binomial distribution and a log link function were performed to test the model. All statistical analyses were performed with SAS software (version 9.2; SAS Institute, Cary, NC).
Results
A total of 437,924 eligible delivery events were identified from January 1, 2005, to September 30, 2010 ( Figure ; Table 1 ). Of the eligible deliveries, 424,880 (97.02%) were singletons; 12,482 (2.85%) were twins, and 562 (0.13%) were triplets or more. The frequency of deliveries with singletons, twins; and higher-order multiples was relatively constant over the study period ( P = .0568). On average, mothers were 31.0 ± 4.6 years old at the delivery, and women who delivered twins or higher-order multiples were approximately 2 years older than their counterparts with singletons ( P < .0001; Table 2 ). IVF/ICSI was used in 1.0% of singletons, 16.9% of twins, and 24.7% of higher-order multiple births ( P < .0001). The most common health plan enrolled was preferred provider organization (61.6%), followed by health maintenance organization (18.3%) and point of service (10.5%). Table 3 shows the presence of comorbidities by delivery multiplicity. Women with twins or higher-order multiples had significantly higher comorbidities in each systemic and localized comorbidity that was examined compared with women who delivered singletons ( P < .0001); the most prevalent systemic comorbidities were hypertension (24.9% and 27.2%) and diabetes mellitus (19.5% and 17.3%) in contrast to singleton deliveries at 10.8% and 13.6%, respectively. The most common localized comorbidities for women with twins or higher-order multiples were cervical incompetence (10.5% and 22.2%) and hemorrhage (11.0% and 14.2%), compared with singleton deliveries at 2.0% and 8.6%, respectively. Table 4 displays the clinical outcomes by delivery multiplicity. Mothers with twins or triplets or more had a longer hospital stay for delivery and higher mortality rate compared with mothers who delivered singletons ( P < .0001). For mothers with singletons, 22.0% of deliveries were through cesarean section in contrast to women with twins or higher-order multiples, for whom cesarean section was the dominant delivery modality (79.1% and 96.3%, respectively). Infants of twins or triplets or more were more likely to be admitted to NICU and had a higher mortality rate compared with infants of singletons (47.7% [triplets or more] vs 24.2% [twins] and 2.9% [singletons]; 2.0% [triplets or more] vs 0.5% [twins] and 0.06% [singletons]; all P < .0001). Similarly, among those infants who stayed in NICU, twins or triplets or more had longer stay compared with singletons (63.6 [triplets or more] vs 31.1 [twins] and 15.2 [singletons] days; all P < .0001).
| Year | Overall, n | Singletons, % | Twins, % | Higher-order multiples, % | P value |
|---|---|---|---|---|---|
| 2005 | 50,513 | 97.00 | 2.87 | 0.17 | .0568 a |
| 2006 | 54,549 | 96.90 | 2.96 | 0.15 | |
| 2007 | 84,955 | 97.02 | 2.87 | 0.11 | |
| 2008 | 97,973 | 97.15 | 2.74 | 0.12 | |
| 2009 | 88,147 | 97.05 | 2.84 | 0.11 | |
| 2010 b | 61,787 | 96.96 | 2.91 | 0.13 | |
| Total | 437,924 | 97.02 | 2.85 | 0.13 |
| Characteristic | Overall | Singletons | Twins | Higher-order multiples | P value |
|---|---|---|---|---|---|
| Age, y a | 31.0 ± 4.6 | 31.0 ± 4.6 | 32.8 ± 4.8 | 33.2 ± 4.6 | < .0001 b |
| Plan type, n (%) | .0043 c | ||||
| Health maintenance organization | 79,960 (18.3) | 77,711 (18.3) | 2133 (17.1) | 116 (20.6) | |
| Point of service | 45,765 (10.5) | 44,365 (10.4) | 1351 (10.8) | 49 (8.7) | |
| Preferred provider organization | 269,838 (61.6) | 261,770 (61.6) | 7732 (62.0) | 336 (59.8) | |
| Other/unknown | 42,361 (9.7) | 41,034 (9.7) | 1266 (10.1) | 61 (10.9) | |
| Region, n (%) | < .0001 c | ||||
| North Central | 112,987 (25.8) | 109,583 (25.8) | 3237 (25.9) | 167 (29.7) | |
| Northeast | 47,864 (10.9) | 46,228 (10.9) | 1566 (12.6) | 70 (12.5) | |
| South | 205,816 (47.0) | 199,836 (47.0) | 5738 (46.0) | 242 (43.1) | |
| West | 69,789 (15.9) | 67,809 (16.0) | 1899 (15.2) | 81 (14.4) | |
| Unknown | 1468 (0.3) | 1424 (0.3) | 42 (0.3) | 2 (0.4) | |
| In vitro fertilization, n (%) | 6589 (1.5) | 4342 (1.0) | 2108 (16.9) | 139 (24.7) | < .0001 c |
| Variable | Pregnancy, % | Odds ratio (95% CI) a | ||||
|---|---|---|---|---|---|---|
| Overall (n = 437,924) | Singleton (n = 424,880) | Twins (n = 12,482) | Higher-order multiples (n = 562) | Twins vs singleton | Higher-order multiples vs singleton | |
| Systemic comorbidity | ||||||
| Hypertension | 11.2 | 10.8 | 24.9 | 27.2 | 2.8 (2.6–2.9) | 3.1 (2.6–3.7) |
| Cardiovascular disease | 1 | 1 | 1.3 | 2 | 1.4 (1.2–1.6) | 2.1 (1.1–3.8) |
| Diabetes mellitus | 13.8 | 13.6 | 19.5 | 17.3 | 1.5 (1.5–1.6) | 1.3 (1.1–1.7) |
| Edema/renal disease | 2.1 | 2.1 | 3.2 | 3.6 | 1.6 (1.4–1.8) | 1.8 (1.1–2.8) |
| Genitourinary infection | 4.4 | 4.4 | 6 | 7.5 | 1.4 (1.3–1.5) | 1.8 (1.3–2.4) |
| Thyroid disease | 2.7 | 2.7 | 4 | 6.2 | 1.5 (1.4–1.7) | 2.4 (1.7–3.4) |
| Anemia | 4.8 | 4.7 | 8.4 | 9.3 | 1.9 (1.8–2.0) | 2.1 (1.6–2.8) |
| Localized comorbidity | ||||||
| Hemorrhage | 8.7 | 8.6 | 11 | 14.2 | 1.3 (1.2–1.4) | 1.7 (1.4–2.2) |
| Chorioamnionitis | 1.5 | 1.5 | 2.1 | 2.9 | 1.4 (1.3–1.6) | 1.9 (1.2–3.2) |
| Amniotic sac disorder | 6.2 | 6.1 | 9.3 | 8.7 | 1.6 (1.5–1.7) | 1.5 (1.1–2.0) |
| Cervical incompetence | 2.2 | 2 | 10.5 | 22.2 | 5.9 (5.5–6.3) | 14.4 (11.8–17.5) |
| Structural abnormality | 4.7 | 4.5 | 9.3 | 14.8 | 2.2 (2.0–2.3) | 3.7 (2.9–4.6) |
a Bivariate logistic regression: probability values are all < .0001.
| Clinical outcome | Pregnancy | Odds ratio (95% CI)/ P value a | |||
|---|---|---|---|---|---|
| Singleton (n = 424,880) | Twins (n = 12,482) | Higher-order multiples (n = 562) | Twins vs singleton | Higher-order multiples vs singleton | |
| Maternal | |||||
| Death, % | 0.007 | 0.024 | 0.18 | 3.5 (1.1–11.6) | 26.1 (3.6–192.0) |
| Cesarean delivery, % | 22.0 | 79.1 | 96.3 | 13.5 (12.9–14.1) | 91.6 (59.2–141.6) |
| Length of hospital stay, d b | 3.3 ± 1.8 | 6.2 ± 8.5 | 13.4 ± 17.7 | < .0001 c | < .0001 c |
| Infant | |||||
| Death, % | 0.06 | 0.5 | 2 | 8.5 (6.4–11.1) | 33.2 (18.1–61.1) |
| Intensive care admission, % | 2.9 | 24.2 | 47.7 | 10.9 (10.4–11.4) | 31.1 (26.3–36.7) |
| Length of intensive care unit stay, d b | 15.2 ± 22.6 | 31.1 ± 37.4 | 63.6 ± 57.5 | < .0001 c | < .0001 c |
a Bivariate logistic regression: probability values are all < .0001
Table 5 shows the average all-cause health care cost of infants, mothers, and overall by health plan type. All-cause health care cost is significantly different across health plan types. Point of service health plans paid much less for higher-order multiples compared with other health plan types. Table 6 displays the mean health care expenses and their 95% CIs for infant, mother, and overall after the adjustment of maternal age, year of delivery, health plan, and geographic region. The expenses for maternal and infant care were significantly higher for known IVF/ICSI-conceived infants compared with other pregnancies for both singletons and twins. This pattern was also observed for high-order multiples; however, the difference was not statistically significant between known IVF/ICSI-conceived infants and other pregnancies. On average, for singleton deliveries, the combined all-cause health care expense from the second trimester to 30 days after the delivery for mothers and up to the first birthday for infants was $21,458 (95% confidence interval [CI], $21,302–21,614) compared with twins at $104,831 (95% CI, $103,402–106,280) and higher-order multiple births at $407,199 (95% CI, $384,984–430,695).
