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The impact of Centering Pregnancy Group Prenatal Care on postpartum family planning

Published:September 09, 2013DOI:https://doi.org/10.1016/j.ajog.2013.09.001

      Objective

      The objective of the study was to evaluate the impact of group prenatal care (GPNC) on postpartum family-planning utilization.

      Study Design

      A retrospective cohort of women continuously enrolled in Medicaid for 12 months (n = 3637) was used to examine differences in postpartum family-planning service utilization among women participating in GPNC (n = 570) and those receiving individual prenatal care (IPNC; n = 3067). Propensity scoring methods were used to derive a matched cohort for additional analysis of selected outcomes.

      Results

      Utilization of postpartum family-planning services was higher among women participating in GPNC than among women receiving IPNC at 4 points in time: 3 (7.72% vs 5.15%, P < .05), 6 (22.98% vs 15.10%, P < .05), 9 (27.02% vs 18.42%, P < .05), and 12 (29.30% vs 20.38%, P < .05) months postpartum. Postpartum family-planning visits were highest among non-Hispanic black women at each interval, peaking with 31.84% by 12 months postpartum. After propensity score matching, positive associations between GPNC and postpartum family-planning service utilization remained consistent by 6 (odds ratio [OR], 1.42; 95% confidence interval [CI], 1.05–1.92), 9 (OR, 1.43; 95% CI, 1.08–1.90), and 12 (OR, 1.44; 95% CI, 1.10–1.90) months postpartum.

      Conclusion

      These findings demonstrate the potential that GPNC has to positively influence women's health outcomes after pregnancy and to improve the utilization rate of preventive health services. Utilization of postpartum family-planning services was highest among non-Hispanic black women, further supporting evidence of the impact of GPNC in reducing health disparities. However, despite continuous Medicaid enrollment, postpartum utilization of family-planning services remained low among all women, regardless of the type of prenatal care they received.

      Key words

      For Editors’ Commentary, see Contents
      See related editorial, page 14
      The interconception period from the postpartum visit and until the following pregnancy is an important time for a woman's health, offering an opportunity to address chronic medical and psychosocial conditions, smoking cessation, and weight loss.
      • Tsui A.O.
      • McDonald-Mosley R.
      • Burke A.E.
      Family planning and the burden of unintended pregnancies.
      Equally important is family planning to enable women to space their pregnancies, lowering their risk for low birthweight and premature birth, both linked with infant mortality.
      • Conde-Agudelo A.
      • Rosas-Bermudez A.
      • Kafury-Goeta A.C.
      Birth spacing and risk of adverse perinatal outcomes: a meta-analysis.
      This is important because nearly half (49%) of all pregnancies in the United States each year are unintended, and of these, about 43% end in abortion.
      • Finer L.B.
      • Zolna M.R.
      Unintended pregnancy in the United States: incidence and disparities, 2006.
      Pregnancy intention and appropriate birth spacing also carry many personal benefits, affording women greater chances of achieving educational and career goals. The realization of such goals translates to economic benefits for both families and society because of the personal and public cost savings associated with fewer unplanned children.
      • Frost J.J.
      • Finer L.B.
      • Tapales A.
      The impact of publicly funded family planning clinic services on unintended pregnancies and government cost savings.
      Many states recognize the importance of this sensitive time period and subsidize the receipt of family-planning services through the various mechanisms that include Medicaid, Medicaid family-planning waiver programs, Title X, and the Title V Maternal and Child Health Block Grant. These services are delivered through a network of public and private providers including local health departments and other safety net providers.
      • Vamos C.A.
      • Daley E.M.
      • Perrin K.M.
      • Mahan C.S.
      • Buhi E.R.
      Approaching 4 decades of legislation in the national family planning program: an analysis of Title X's history from 1970 to 2008.
      Developing appropriate programs and policies that enable women to access postpartum family-planning services is important for women's and infant health as well as for women to be able to realize their personal and professional goals. Currently routine postpartum care includes patient education that informs women about family-planning services and the benefits of using them; however, evidence demonstrating the effectiveness offering such education postpartum is relatively weak.
      • Lopez L.M.
      • Hiller J.E.
      • Grimes D.A.
      • Chen M.
      Education for contraceptive use by women after childbirth.
      Limited research suggests prenatal counseling may play a significant role in initiation of postpartum family-planning utilization.
      • Hernandez L.E.
      • Sappenfield W.M.
      • Goodman D.
      • Pooler J.
      Is effective contraceptive use conceived prenatally in Florida? The association between prenatal contraceptive counseling and postpartum contraceptive use.
      Centering Pregnancy is an innovative prenatal care program that may contribute positively to the transition from childbirth to postpartum life that includes the use of family planning. The Centering Pregnancy model of group prenatal care (GPNC) has been described by Sharon Schindler-Rising
      • Rising S.S.
      • Kennedy H.P.
      • Klima C.S.
      Redesigning prenatal care through CenteringPregnancy.
      • Lathrop B.
      A systematic review comparing group prenatal care to traditional prenatal care.
      • Ickovics J.R.
      • Kershaw T.S.
      • Westdahl C.
      • et al.
      Group prenatal care and perinatal outcomes: a randomized controlled trial.
      • Tanner-Smith E.E.
      • Steinka-Fry K.T.
      • Lipsey M.W.
      The effects of CenteringPregnancy group prenatal care on gestational age, birth weight, and fetal demise.
      in publications detailing the content of the unique curriculum and style of care.
      • Klima C.
      • Norr K.
      • Vonderheid S.
      • Handler A.
      Introduction of CenteringPregnancy in a public health clinic.
      The Centering Healthcare Institute (Boston, MA) provides technical assistance and curricular materials to practices providing this model of prenatal care. This GPNC model includes a curriculum delivered in a series of 10 group sessions over a 6 month period of time.
      During each 2-hour session, groups of 8-12 pregnant women due to deliver in the same month receive a physical assessment from a credentialed health care provider, participate in an educational curriculum, and are provided with a supportive environment that allows for relationship-building among participants.
      • Klima C.
      • Norr K.
      • Vonderheid S.
      • Handler A.
      Introduction of CenteringPregnancy in a public health clinic.
      In most groups, prenatal care is provided by certified nurse midwives or nurse practitioners. Women with medically high-risk pregnancies, such as those with chronic hypertension, pregestational diabetes, or multiple gestations, are typically considered ineligible for group care because they might require more intensive medical management than can be provided in a group setting.
      • Lathrop B.
      A systematic review comparing group prenatal care to traditional prenatal care.
      Initial studies on the GPNC model have been encouraging and suggest that women participating in GPNC may experience improvements in both health outcomes and health behaviors.
      • Lathrop B.
      A systematic review comparing group prenatal care to traditional prenatal care.
      Although the body of literature is not fully conclusive, selected studies do suggest that GPNC participants experience decreases in the rates of preterm birth
      • Ickovics J.R.
      • Kershaw T.S.
      • Westdahl C.
      • et al.
      Group prenatal care and perinatal outcomes: a randomized controlled trial.
      • Picklesimer A.H.
      • Billings D.
      • Hale N.
      • Blackhurst D.
      • Covington-Kolb S.
      The effect of CenteringPregnancy group prenatal care on preterm birth in a low-income population.
      and increased birthweights
      • Lathrop B.
      A systematic review comparing group prenatal care to traditional prenatal care.
      • Tanner-Smith E.E.
      • Steinka-Fry K.T.
      • Lipsey M.W.
      The effects of CenteringPregnancy group prenatal care on gestational age, birth weight, and fetal demise.
      relative to their counterparts receiving individual prenatal care (IPNC). Other studies also suggest increased rates of breastfeeding,
      • Lathrop B.
      A systematic review comparing group prenatal care to traditional prenatal care.
      • Ickovics J.R.
      • Kershaw T.S.
      • Westdahl C.
      • et al.
      Group prenatal care and perinatal outcomes: a randomized controlled trial.
      • Klima C.
      • Norr K.
      • Vonderheid S.
      • Handler A.
      Introduction of CenteringPregnancy in a public health clinic.
      • Grady M.A.
      • Bloom K.
      Pregnancy outcomes of adolescents enrolled in a CenteringPregnancy program.
      improved patient satisfaction with prenatal care received,
      • Lathrop B.
      A systematic review comparing group prenatal care to traditional prenatal care.
      • Ickovics J.R.
      • Kershaw T.S.
      • Westdahl C.
      • et al.
      Group prenatal care and perinatal outcomes: a randomized controlled trial.
      • Klima C.
      • Norr K.
      • Vonderheid S.
      • Handler A.
      Introduction of CenteringPregnancy in a public health clinic.
      • Robertson B.
      • Aycock D.M.
      • Darnell L.A.
      Comparison of centering pregnancy to traditional care in Hispanic mothers.
      and improved readiness for childbirth and parenting.
      • Lathrop B.
      A systematic review comparing group prenatal care to traditional prenatal care.
      • Ickovics J.R.
      • Kershaw T.S.
      • Westdahl C.
      • et al.
      Group prenatal care and perinatal outcomes: a randomized controlled trial.
      • Baldwin A.
      Comparison of selected outcomes of CenteringPregnancy versus traditional. prenatal care.
      The Centering Pregnancy educational curriculum includes sessions on family planning. However, the effects of participation in GPNC on postpartum health service utilization, including family-planning services, have not been studied. We posit that targeted facilitation of group discussion on key material contained in the curriculum and continued peer support could serve to reinforce important messages related to postpartum family-planning utilization among women participating in GPNC that would not be present for women receiving IPNC delivered through a traditional clinic-based service delivery model.
      We sought to evaluate the effects of participation in GPNC on the utilization of family-planning services following delivery, compared with women who had received IPNC.

      Materials and Methods

      In March 2009, the Greenville Health System obstetric practice began providing Centering Pregnancy GPNC according to the trademarked curriculum. Formal site approval was granted by the Centering Healthcare Institute in February 2010. Participation in GPNC was not randomized; rather, women were free to select the care pathway they preferred. Each month, approximately 30-45 women chose to receive GPNC and were assigned to one of 3 or 4 new groups each month. The total number of groups attended was recorded for each participant, and women were permitted to withdraw from GPNC and continue with IPNC if desired. Participation in GPNC was defined as attendance at even 1 group session.
      Medical care in groups was provided by nurse practitioners and certified nurse midwives, who also served as the main facilitators of each group. Nursing assistants served as cofacilitators. Historically, the majority of Medicaid-eligible women delivering at Greenville Memorial Hospital (85%) receive their prenatal care in the same hospital-owned clinic offering GPNC. Therefore, the majority of women in the matched cohort would have received IPNC from the same nurse practitioners and nurse midwives providing GPNC. A minority would have been seen in 1 of the 5 affiliated private practices also seeing Medicaid-eligible patients. After the first 8 months of implementation, many groups also included a medical student, a resident physician in family medicine, or a resident physician in obstetrics and gynecology.
      In October 2011, the authors received approval from the Institutional Review Boards of the Greenville Health System and the University of South Carolina (Pro00013703) to analyze postpartum family-planning utilization among participants in GPNC and recipients of IPNC. A retrospective cohort of Medicaid-insured women with a singleton live birth occurring at Greenville Memorial Hospital between March 2009 and March 2012 was drawn from the vital statistics databases maintained at the Office of Research and Statistics (ORS) of the South Carolina Budget and Control Board. ORS serves as a repository for all health information in the State of South Carolina, including mandatory reporting for all vital records, hospital discharges, and Medicaid billing files. The ORS data oversight committee, which is equivalent to an institutional review board, also approved the data release.
      Because women must enroll in GPNC early in gestation and because the program is offered only to medically low-risk women, only women entering prenatal care within the first 16 weeks of pregnancy with no indication of pregestational diabetes or hypertension were included in the study. For women with more than 1 birth during the study period, only the first delivery was included in the analysis. Furthermore, the study was limited to only women with continuous Medicaid coverage for 12 months following delivery. This included women enrolled in a traditional Medicaid program and those enrolled under the Medicaid Family Planning Waiver. Receipt of family planning services was tracked using secondary billing records from Medicaid available from ORS.
      Utilization of family-planning services postpartum served as the primary outcome variable of interest. A dichotomous (yes/no) variable was created indicating a visit made by 3, 6, 9, or 12 months postpartum. Visit data were obtained using the Medicaid-approved family-planning program billing and modifier codes. Effectively these codes encompass any visit billed under the Medicaid Family Planning Program including initial (Current Procedural Terminology [CPT] codes 99201-99205), annual (CPT codes 99212-99215), supply (CPT codes 99211-99215), or counseling (CPT codes 99401 or 99402) visits.
      The initial and annual visits include a complete physical examination, appropriate laboratory testing, the distribution of contraception prescriptions/supplies, or counseling on sexually transmitted disease prevention. Supply and counseling visits are less intense but specifically address contraception needs or adjustments of methods for enrolled women. Participation in GPNC served as the primary independent variable of interest.
      Additional variables were included in the analysis and used to establish the propensity-based matched cohort. The Anderson's Behavioral Model for Health Services Use served as the conceptual framework for selecting appropriate covariates.
      • Anderson R.
      Revisiting the behavioral model and access to medical care: does it matter?.
      The Anderson model conceptualizes health utilization as a function of the influences of predisposing characteristics, enabling factors, and individual need or perception of need for services.
      Predisposing characteristics included parity, maternal race/ethnicity, age, and educational achievement. Enabling factors included marital status and adequacy of prenatal care as defined by Adequacy of Prenatal Care Utilization Index (APCNU).
      • Kotelchuck M.
      An evaluation of the Kessner Adequacy of Prenatal Care Index and a proposed Adequacy of Prenatal Care Utilization Index.
      The APNCU characterizes prenatal care utilization according to the timing of initiation and adequacy of visits received. Care is defined as inadequate for women initiating prenatal care after the fourth month of pregnancy or women receiving less than 50% of recommended visits. Intermediate/adequate prenatal care includes women entering prenatal care in months 1-4 who received 50-109% of the recommended visits. Finally, adequate plus care includes women entering prenatal care in months 1-4 who received more than 110% of the recommended visits.
      Need factors included overweight/obesity (defined as a body mass index [BMI] higher than 25.0 kg/m2) and smoking during pregnancy. Additional need factors also included gestational diabetes and gestational hypertension. These variables were also included to account for potential differences in pregnancy complications emerging after selection into a mode of prenatal care. These variables were derived from birth certificate records.
      Initial analysis focused on examining the impact of GPNC on postpartum family-planning utilization among the full cohort of Medicaid eligible women. The specific location of prenatal care for the control group women was not available. However, no other affiliated practices were providing GPNC during this time period. Bivariate analysis of categorical outcomes was assessed using a χ2 test for independence and unadjusted odds ratios were obtained. An additional bivariate analysis was conducted among racial/ethnic subgroups. It should be noted that the original cohort included a very small number of Hispanic women with continuous Medicaid coverage; therefore, analysis by ethnicity was not included in the results.
      Multivariate logistic regression was used to examine differences in utilization of postpartum family-planning services among women participating in GPNC compared with those receiving IPNC.
      To improve the rigor of the study design, propensity scores were also used to establish a matched cohort for further analysis. Propensity scoring is a method of matching that uses available background information on the characteristics of the study population to establish matched pairs of treated participants and controls.
      • Rubin D.B.
      The design versus the analysis of observational studies for causal effects: parallels with the design of randomized trials.
      This form of matching provides a mechanism for balancing data and minimizing observable differences between the 2 groups.
      • Rubin D.B.
      The design versus the analysis of observational studies for causal effects: parallels with the design of randomized trials.
      To derive the propensity score used for matching, a logistic regression model with participation in group prenatal care as the primary outcome variable was estimated using the previously mentioned covariates. The predicted probability of participating in GPNC from the model serves as the propensity score. The propensity score was transformed using a logarithmic scale and entered into the Stata PSMATCH2 command (StataCorp, College Station, TX) and used to establish matched pairs on a 1:1 basis. Only values included in the common support region, the area in which the distribution of propensity scores for participation in GPNC overlaps with the distribution of propensity scores for participation in IPNC, were used in the analysis. This excluded women who were least likely to produce a reliable match based on the observed characteristics. In addition, a caliper representing 0.25 of the SD of the mean propensity score was used when matching. Use of the caliper limits the range in which matches can be made further assuring ideal matching and producing a balanced cohort.
      • Guo S.
      • Fraser M.W.
      Propensity score analysis: statistical methods and applications.
      Characteristics of the study population before and after propensity score matching were assessed using a χ2 test for independence to ensure that the data were fully balanced with respect to the covariates used to derive the propensity score. Utilization of the postpartum family-planning services at 3, 6, 9, and 12 months also was examined using the propensity-matched cohort.

      Results

      During the study period, there were 9974 deliveries to women with Medicaid at the study institution. After initial exclusions, 3637 women remained in the study cohort. Of these, 570 (16%) participated in the GPNC program (Figure). Women in group care attended a median of 8 (interquartile range, 5–9) sessions of the scheduled 10 sessions. Approximately 50 women (of the 570) withdrew from group care after at least 1 completed group visit but were evaluated with the GPNC cohort in an intent-to-treat model.
      Figure thumbnail gr1
      FigureStudy population and exclusion criteria
      The figure provides an overview of the study population and exclusion criteria imposed on the cohort.
      Hale. Group prenatal care and postpartum family planning. Am J Obstet Gynecol 2014.
      The characteristics of the study population before and after propensity score matching are presented in Table 1. Prior to propensity score matching, notable differences in the characteristics of the study population existed. Well over half (64.91%, n = 370) of pregnancies among GPNC were first births compared with 42.78% (n = 1312) among IPNC (P < .05). Moreover, women participating in GPNC were more often of black race, younger maternal age, and had less educational attainment relative to their counterparts in IPNC (P < .05 for all).
      Table 1Characteristics of the study population before and after propensity score matching (March 2009 through March 2012)
      Maternal characteristicsBefore propensity score matchingAfter propensity score matching
      Group PNCIndividual PNCP valueGroup PNCIndividual PNCP value
      n5703067550550
      Parity< .001.751
       Nulliparous370 (64.91%)1312 (42.78%)364 (66.18%)359 (65.27%)
       Multiparous200 (35.09%)1755 (57.22%)186 (33.82%)191 (34.73%)
      Race< .001.952
       White303 (53.16%)1918 (62.54%)293 (53.27%)294 (53.45%)
       Black/other267 (46.84%)1149 (37.46%)257 (46.73%)256 (46.55%)
       Hispanic ethnicity42 (7.37%)161 (5.25%).04341 (7.45%)38 (6.91%).726
      Age, y< .001.880
       Younger than 20142 (24.91%)497 (16.20%)140 (25.45%)142 (25.82%)
       20-34406 (71.23%)2373 (77.37%)390 (70.91%)385 (70.00%)
       Older than 3522 (3.826)197 (6.42%)20 (3.64%)23 (4.18%)
      Education.003.849
       Less than high school157 (27.54%)896 (29.21%)154 (28.00%)157 (28.55%)
       High school diploma/some college384 (67.37%)1897 (61.85%)367 (66.73%)368 (66.91%)
       College/graduate degree29 (5.09%)274 (8.93%)29 (5.27%)25 (4.55%)
      Enabling
       Marital status< .001.867
       Single/divorced449 (81.49%)2121 (73.31%)448 (81.45%)450 (81.82%)
       Married102 (18.51%)772 (26.69%)102 (18.55%)100 (18.18%)
      Adequacy of prenatal care< .001.947
       Inadequate19 (3.33%)148 (4.83%)18 (3.27%)20 (3.64%)
       Intermediate/adequate172 (30.18%)1548 (50.47%)166 (30.18%)165 (30.00%)
       Adequate plus379 (66.49%)1371 (44.70%)366 (66.55%)365 (66.36%)
      Individual need
       Overweight/obese (BMI >25.0 kg/m2)275 (48.33%)1488 (48.82%).172266 (48.36%)265 (48.18%).952
       Smoking during pregnancy112 (19.65%)773 (25.20%).005106 (19.27%)110 (20.00%).761
       Gestational diabetes12 (2.11%)202 (6.59%)< .00112 (2.18%)9 (1.64%).509
       Gestational hypertension82 (14.39%)505 (16.47%).21279 (14.36%)77 (14.00%).863
      Hale. Group prenatal care and postpartum family planning. Am J Obstet Gynecol 2014.
      Among enabling factors, 81.49% (n = 449) of women participating in GPNC were unmarried compared with 73.31% (n = 2121) among those receiving IPNC (P < .05). Adequacy of prenatal care was higher among GPNC (P < .05). Among need factors, smoking during pregnancy was lower among women participating in GPNC (19.65%, n = 112) compared with 25.2% (n = 773) among those receiving IPNC (P < .05). Moreover, only 2.11% (n = 12) of women participating in GPNC developed gestational diabetes relative to 6.59% (n = 202) among women in receiving IPNC (P < .05).
      After propensity score matching, approximately 20 women participating in GPNC lacked a suitable match based on the matching criteria imposed on the cohort. These women were excluded from further analysis. The remaining 550 matched pairs yielded a balanced cohort with no observable differences in covariates between the study groups (Table 1).
      Utilization of a family-planning service and unadjusted odds of using postpartum family-planning services prior to propensity score matching are shown in Table 2. Utilization of postpartum family-planning services was higher among women participating in GPNC at 3, 6, 9, and 12 months postpartum, compared with their counterparts receiving IPNC. By 3 months postpartum, 7.72% of women in GPNC received a visit compared with 5.15% among those in IPNC (odds ratio [OR], 1.54; 95% confidence interval [CI], 1.09–2.18).
      Table 2Results of bivariate analysis before propensity score matching
      VariablePercentageOR (95% CI)
      Group PNC (n = 570)Individual PNC (n = 3067)
      Total
       3 months
      Statistically significant at P < .05.
      7.725.151.54 (1.09–2.18)
       6 months
      Statistically significant at P < .05.
      22.9815.101.68 (1.35–2.09)
       9 months
      Statistically significant at P < .05.
      27.0218.421.64 (1.33–2.01)
       12 months
      Statistically significant at P < .05.
      29.3020.381.62 (1.32–1.98)
      White
       3 months6.934.801.48 (0.91–2.41)
       6 months
      Statistically significant at P < .05.
      21.4513.191.79 (1.33–2.44)
       9 months
      Statistically significant at P < .05.
      25.4115.951.79 (1.35–2.39)
       12 months
      Statistically significant at P < .05.
      27.0617.731.72 (1.30–2.78)
      Black
       3 months8.615.741.55 (0.94–2.53)
       6 months
      Statistically significant at P < .05.
      24.7218.281.47 (1.07–2.01)
       9 months
      Statistically significant at P < .05.
      28.8422.541.39 (1.03–1.88)
       12 months
      Statistically significant at P < .05.
      31.8424.801.42 (1.06–1.89)
      CI, confidence interval; OR, odds ratio; PNC, prenatal care.
      Hale. Group prenatal care and postpartum family planning. Am J Obstet Gynecol 2014.
      a Statistically significant at P < .05.
      Utilization of a family-planning service was higher by 6 months postpartum among women in GPNC (22.98%) compared with 15.10% of women receiving IPNC (OR, 1.68; 95% CI, 1.35–2.09). Approximately 1 in 4 women participating in GPNC (27.02%) used a family-planning service by 9 months postpartum compared with 18.42% among women receiving IPNC (OR, 1.64; 95% CI, 1.33–2.01). By 12 months postpartum, using family-planning services remained markedly higher among women participating in GPNC (29.30%) compared with 20.38% of women receiving IPNC (OR, 1.62; 95% CI, 1.32–1.98).
      Observed relationships were consistent among the racial subgroups. Receipt of family-planning services was higher among both non-Hispanic white and non-Hispanic black women participating in GPNC relative to their counterparts receiving IPNC by the 6, 9, and 12 month intervals. Moreover, postpartum family-planning visits was highest among non-Hispanic black women at each interval, peaking with 31.84% of non-Hispanic black women utilizing a service by the 12 month interval.
      Adjusted odds ratios before and after propensity score matching are presented in Table 3. Before propensity score matching, the adjusted odds of using a family planning service by 3 (adjusted OR [AOR], 1.48; 95% CI, 1.02–2.14), 6 (AOR, 1.42; 95% CI, 1.11–1.81), 9 (AOR, 1.42; 95% CI, 1.13–1.79), and 12 (AOR, 1.40; 95% CI, 1.13–1.74) months postpartum are markedly higher among women participating in GPNC compared with women receiving IPNC. After propensity score matching, the increased likelihood of seeking a postpartum family-planning visit among women receiving GPNC was attenuated at the 3 month interval (OR, 1.33; 95% CI, 0.83–2.15). However, observed relationships at the 6 (OR, 1.42; 95% CI, 1.05–1.92), 9 (OR, 1.43; 95% CI, 1.08–1.90), and 12 (OR, 1.44; 95% CI, 1.10–1.90) month intervals remained consistent.
      Table 3Results from the multivariate and propensity matched analysis
      OutcomeAOR (95% CI)
      Multivariate regression models
      Model adjusted for parity, mother's age, mother's education, mother's race/ethnicity, marital status, adequacy of PNC, BMI, smoking during pregnancy, gestational diabetes, and gestational hypertension.
      Propensity score–matched cohort regression models
      Utilization of family-planning visit
      By 3 months
       Group PNC1.45 (1.00–2.10)1.33 (0.83–2.15)
       Individual PNCReferentReferent
      By 6 months
       Group PNC1.42 (1.12–1.80)1.42 (1.05–1.92)
       Individual PNCReferentReferent
      By 9 months
       Group PNC1.40 (1.12–1.74)1.43 (1.08–1.90)
       Individual PNCReferentReferent
      By 12 months
       Group PNC1.40 (1.13–1.74)1.44 (1.10–1.90)
       Individual PNCReferentReferent
      AOR, adjusted odds ratio; BMI, body mass index; CI, confidence interval; PNC, prenatal care.
      Hale. Group prenatal care and postpartum family planning. Am J Obstet Gynecol 2014.
      a Model adjusted for parity, mother's age, mother's education, mother's race/ethnicity, marital status, adequacy of PNC, BMI, smoking during pregnancy, gestational diabetes, and gestational hypertension.

      Comment

      Our main finding is that continuously insured women enrolled in Medicaid who participate in group prenatal care are more likely to access family-planning services by 3, 6, 9, and 12 months postpartum, relative to a comparable cohort of women who received individual prenatal care. This result demonstrates the potential that GPNC has to positively influence women's health outcomes after pregnancy. Additionally, within the GPNC cohort, we found utilization of postpartum family-planning services to be higher among non-Hispanic black women compared with their non-Hispanic white counterparts. Thus, GPNC may be a pathway toward improving racial disparities related to perinatal health and health service-seeking outcomes.
      • Ickovics J.R.
      • Kershaw T.S.
      • Westdahl C.
      • et al.
      Group prenatal care and perinatal outcomes: a randomized controlled trial.
      Although our finding suggests GPNC is associated with an increased likelihood of postpartum family-planning service utilization, the overall utilization of these services was relatively low for both the GPNC and IPNC groups. This finding is particularly relevant given the study population was limited to only those women with continuous Medicaid coverage for the duration of the study period (12 months).
      Presumably, reforms from the Patient Protection and Affordable Care Act (PPACA) extending Medicaid coverage to previously uninsured women would remove lack of insurance coverage as a barrier for using important postpartum health services such as family planning. However, utilization of these services was low, even among women who were continuously insured. Additional factors beyond insurance coverage that potentially influence the uptake of these important services warrants further investigation.
      The strengths of this study include the large, racially diverse cohort available for evaluation. The large study population made it possible for us to use propensity score matching to eliminate potential selection bias evident in the sample. This study design is an improvement on traditional regression models prone to selection bias from observed differences between comparison groups. Results from the balanced propensity matched cohort analysis are more reliable than traditional cross-sectional study designs and improve the ability to make causal inferences.
      • Kotelchuck M.
      An evaluation of the Kessner Adequacy of Prenatal Care Index and a proposed Adequacy of Prenatal Care Utilization Index.
      • Rubin D.B.
      The design versus the analysis of observational studies for causal effects: parallels with the design of randomized trials.
      • Guo S.
      • Fraser M.W.
      Propensity score analysis: statistical methods and applications.
      • Rubin D.B.
      Estimating causal effects from large data sets using propensity scores.
      We note several study limitations. Although claims data are useful for obtaining results on larger cohorts of women, a certain amount of precision is sacrificed. These data came from administrative billing data and were not collected for research purposes. Misclassification of Medicaid enrollment, coverage, and family-planning service utilization is possible. We also would have liked to capture information on the specific method of contraception chosen postpartum; however, this level of detail was not available for this study in the data available.
      In addition, it is possible that the family-planning needs of women were addressed during the initial postpartum visit but were not billed as a family-planning visit. In these instances results from our analysis would underestimate the level of utilization among the study populations. Furthermore, differences in postpartum sterilization among the study populations could affect the need for postpartum family-planning services; however, no evidence was found in the data to suggest systematic differences in sterilization was present.
      It should be noted that no intrauterine contraceptive devices were inserted during the inpatient hospital stay. The South Carolina Medicaid program did not cover the placement of long-acting reversible contraceptive methods during the study period. Finally, although propensity score matching is among the strongest study designs available, given the available data, unobserved differences in the characteristics of the study groups can not be accounted for and can be a source of bias.
      These findings suggest that GPNC promotes improved pregnancy outcomes by affecting maternal health behaviors and improves health literacy by establishing a continuum of care for women extending from pregnancy through the postpartum period. Our findings suggest that GPNC does exert some influence on transitioning to postpartum family-planning services, particularly in non-Hispanic black women. Although the mechanisms explaining our findings are unclear, continued reinforcement of key messages with facilitated group discussion and peer support are important features of GPNC that are not routinely present in IPNC.
      Larger prospective, randomized trials are needed to confirm the favorable effects of GPNC on selected health and health service outcomes and provide additional insight on the specific mechanisms underpinning observed results. Future studies should also examine the content of GPNC visits and address long-term outcomes, such as the duration of the interconceptional interval and the outcome of subsequent pregnancies.

      Acknowledgments

      We would like to acknowledge the South Carolina Chapter of the March of Dimes for their continued support of the implementation of the Centering Pregnancy program at the study site. We would also like to acknowledge the contributions of the South Carolina Budget and Control Board, Office of Research and Statistics, in compiling and linking the data used for the study.

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