Association of Maternal Medical Conditions and Unfavorable Birth Outcomes: Findings from the 1996–2003 Mississippi Linked Birth and Death Data

This study aimed to identify factors contributing to high rates of preterm birth (PTB), low birth weight (LBW) and infant mortality in Mississippi while considering both traditional risk factors and maternal medical conditions. The retrospective cohort study used 1996–2003 Mississippi linked birth and infant death files. Multiple logistic regression was used to investigate association between maternal medical conditions and unfavorable birth outcomes. Along with traditional risk factors, hypertension was significantly associated with PTB and LBW. Women with hypertension were about 2.2 and 3.2 times as likely to have PTB and LBW, respectively. Hydramnios/oligohydramnios increased 1.8–4.4 folds of risk for PTB, LBW and infant death and was significantly associated with the unfavorable birth outcomes. Non-Hispanic black women were about 1.5–2.0 times as likely to have an unfavorable birth outcome compared to non-Hispanic white women. Maternal education and prenatal care effect appeared to be modified by maternal race. Certain maternal medical conditions may be contributing to PTB, LBW and infant mortality rates identifying preconception and prenatal healthcare as possible strategies for reducing unfavorable outcomes. Results suggest that different risk profiles for unfavorable outcomes may exist according to maternal race highlighting the need to consider racial groups separately when further exploring the sociodemographic and/or health-related factors that contribute to unfavorable birth outcomes.     

The Association Between Rural-Urban Continuum, Maternal Education and Adverse Birth Outcomes in Québec, Canada

ABSTRACT:  Context: Rural relative to urban area and low socioeconomic status (SES) are associated with adverse birth outcomes. Whether a graded association of increasing magnitude is present across the urban-rural continuum, accounting for SES, is unclear. We examined the association between rural-urban continuum, SES and adverse birth outcomes. Methods: Singleton births from 1999 to 2003 (n = 356,147) were linked to Québec municipalities ranked on a continuum of 3 urban and 4 rural areas based on population and economic base. Maternal education was used to represent SES. Odds ratios (OR) were calculated for preterm birth (PTB), low birth weight (LBW), and small-for-gestational-age (SGA) birth, accounting for municipality and individual-level covariates. We used stratified analyses to examine interaction between SES and rural-urban continuum. Findings: Relative to metropolitan area residence, living in small urban or rural areas was associated with adverse birth outcomes. Living in rural areas was associated with SGA birth (OR 1.11, 95% CI 1.05-1.17) and LBW (OR 1.15, 95% CI 1.05-1.26), and living in small urban areas was associated with PTB (OR 1.14, 95% CI 1.08-1.20). Upon stratification by education, living in remote rural relative to metropolitan areas was associated with adverse birth outcomes among university educated mothers only, and living in small urban areas was associated with adverse birth outcomes among mothers with lesser but not higher education. An SES gradient was present in all rural-urban areas, particularly for SGA birth. Conclusion: Differences in perinatal health exist across the rural-urban continuum, and maternal education has a modifying influence.     

Independent and Interactive Associations of Prenatal Mood and Substance Use With Infant Birth Outcomes

The main objective of this work is to examine low prenatal mood, alcohol and tobacco use and rates of preterm (PTB) and low birth weight (LBW) births among women in Minnesota between 2002 and 2006. We examined the Minnesota version of the national, cross-sectional survey of postpartum women, the Pregnancy Risk Assessment Monitoring System (MN PRAMS). Of the 11,891 women sampled in 2002–2006, 7,457 had complete data for analysis; the weighted response rates averaged 76%. The major variables of interest were: LBW, PTB, maternal mood during pregnancy, prenatal alcohol use, prenatal tobacco use and interaction terms created from the mood and substance use variables. Women with low mood who used tobacco during pregnancy were twice as likely to have a LBW infant as women who did not smoke and reported high mood (AOR = 2.12, 95% CI: 1.35, 3.33, P = 0.001). Among women who abstained from alcohol during pregnancy, those with low mood were at an increased risk for PTB (AOR = 1.95, 95% CI: 1.54–2.45, P < 0.0001) compared to women with high mood. Low maternal mood was associated with increased risks for PTB, and LBW births among MN PRAMS respondents. Substance use and low prenatal mood co-occur and the combined effect on PTB and LBW birth outcomes warrants further investigation.     

Factors Predicting Birth Weight in a Low-Risk Sample: The Role of Modifiable Pregnancy Health Behaviors

Objectives: The purpose of the present study was to examine background and modifiable pregnancy health behavior factors predicting infant birthweight in an economically and educationally disadvantaged sample with low medical risk. Methods: Participants were recruited from a family practice center in rural Appalachia. Participants: Over 220, predominantly Caucasian and lower SES women with low risk pregnancies were included in the sample. Data were collected through systematic chart review. Half of the women smoked during pregnancy and over 10% gave birth to low birth weight (LBW; < 2500 g) babies. Results: Compared with those who gave birth to normal weight newborns, women with LBW babies had more miscarriages, but did not differ significantly on other background factors. Women who delivered LBW babies gained less weight during pregnancy and were more likely to smoke than remaining women. After control for background factors, modifiable pregnancy health behavior factors (weight gain, prenatal care, smoking, alcohol and substance use) accounted for over 11% of birth weight variance, with nearly 7% attributable solely to smoking. Conclusions: Pregnancy smoking was the strongest behavioral predictor of LBW in this economically and educationally disadvantaged rural sample, suggesting that efforts to reduce LBW in similar populations should include targeting pregnancy smoking.     

Contrasting socioeconomic gradients in small for gestational age and preterm birth in Argentina, 2003–2007

Objectives

To examine the socioeconomic gradients in birth outcomes among singleton infants in Argentina, 2003–2007.

Methods

We analyzed data of 3,230,031 singleton infants born in 2003–2007, obtained from vital statistics. Associations between birth outcomes [small for gestational age (SGA), low birth weight (LBW), and preterm birth (PTB)] and socioeconomic indicators (maternal education and area-based material deprivation quintiles) were assessed with logistic regression.

Results

The risk of SGA increased with higher socioeconomic disadvantage, but that of PTB decreased. Compared to mothers who attained a tertiary or university degree, mothers who did not complete primary school were more likely to have a SGA infant [adjusted OR (95 % CI): 1.65 (1.62, 1.68)], but less likely to deliver preterm [0.92 (0.90, 0.94)]. As a result of the conflicting trends in SGA and PTB, LBW exhibited inconsistent socioeconomic gradients.

Conclusions

The excess risk of adverse birth outcomes associated with socioeconomic disadvantage was consistently reflected by SGA, but not by LBW and PTB. These findings challenge the usefulness of LBW as an indicator population health. Further research is needed to explain the reverse socioeconomic gradients in PTB.     

Rising Disparities in Severe Adverse Birth Outcomes Among Haitians in Québec, Canada, 1981–2006

Perinatal health data for Haitians are scant. We evaluated adverse birth outcomes for Haitians in Québec, Canada. We analyzed 2,124,909 live births from 1981 to 2006. Haitian ethnicity was assessed using maternal birth country (Haiti, other Caribbean country, other foreign country, Canada) and home language (Creole, French/English but Creole mother tongue, French/English, other). Associations between ethnicity and preterm birth (PTB), low birth weight (LBW), and small-for-gestational-age (SGA) birth were calculated. Adverse birth outcomes were more common among mothers with Haitian ethnicity. Relative to Canadian-born mothers, odds for Haitian-born mothers were 4 times greater for extreme PTB (≤27 weeks), twice greater for very PTB (28–31 weeks), and 25% higher for moderate PTB (32–36 weeks). Patterns were similar for SGA birth and severe cases of LBW. Despite overall decreases LBW and SGA birth, relative and absolute inequalities increased over time. Perinatal health inequalities are increasing for Haitian-born mothers.     

The Status of Women's Reproductive Rights and Adverse Birth Outcomes

BackgroundReproductive rights—the ability to decide whether and when to have children—shape women's socioeconomic and health trajectories across the life course. The objective of this study was to examine reproductive rights in association with preterm birth (PTB; <37 weeks) and low birth weight (LBW; <2,500g) across states in the United States.MethodsAnalysis included records for all live births in the United States in 2012 grouped by state. A reproductive rights composite index score was assigned to records from each state based on the following indicators for the year before birth (2011): mandatory sex education, expanded Medicaid eligibility for family planning services, mandatory parental involvement for minors seeking abortion, mandatory abortion waiting periods, public funding for abortion, and percentage of women in counties with abortion providers. Scores were ranked by tertile with the highest tertile reflecting states with strongest reproductive rights. We fit logistic regression models with generalized estimating equations to estimate the odds ratios and 95% confidence intervals for PTB and LBW associated with reproductive rights score controlling for maternal race, age, education, and insurance and state-level poverty.ResultsStates with the strongest reproductive rights had the lowest rates of LBW and PTB (7.3% and 10.6%, respectively) compared with states with more restrictions (8.5% and 12.2%, respectively). After adjustment, women in more restricted states experienced 13% to 15% increased odds of PTB and 6% to 9% increased odds of LBW compared with women in states with the strongest rights.ConclusionsState-level reproductive rights may influence likelihood of adverse birth outcomes among women residents.     

Residential Segregation and the Health of African-American Infants: Does the Effect Vary by Prevalence?

Segregation effects may vary between areas (e.g., counties) of low and high low birth weight (LBW; <2,500?g) and preterm birth (PTB; <37?weeks of gestation) rates due to interactions with area differences in risks and resources. We assess whether the effects of residential segregation on county-level LBW and PTB rates for African-American infants vary by the prevalence of these conditions. The study sample includes 368 counties of 100,000 or more residents and at least 50 African-American live births in 2000. Residentially segregated counties are identified alternatively by county-level dissimilarity and isolation indices. Quantile regression is used to assess how residential segregation affects the entire distributions of county-level LBW and PTB rates (i.e. by prevalence). Residential segregation increases LBW and PTB rates significantly in areas of low prevalence, but has no such effects for areas of high prevalence. As a sensitivity analysis, we use metropolitan statistical area level data and obtain similar results. Our findings suggest that residential segregation has adverse effects mainly in areas of low prevalence of LBW and preterm birth, which are expected overall to have fewer risk factors and more resources for infant health, but not in high prevalence areas, which are expected to have more risk factors and fewer resources. Residential policies aimed at area resource improvements may be more effective.     

Adverse Birth Outcomes Among Women of Advanced Maternal Age With and Without Health Conditions in Maryland

BackgroundAdvanced maternal age (AMA) has been linked to both higher risk of adverse birth outcomes and higher levels of comorbidities. It is unclear if adverse outcomes are higher for older healthy women. This study examined the association between AMA and adverse birth outcomes among women with and without preexisting and pregnancy-related health conditions.MethodsAnalysis of data for 14,933 singleton births between 2004 and 2015 from the population-based Maryland Pregnancy Risk Assessment Monitoring System was conducted, comparing women aged 20–34 years and 35 years and older. Multivariable logistic regression estimated the difference in odds of preterm birth (PTB) and low birthweight (LBW) by age group among women with and without health conditions. The analysis of women without health conditions was stratified by parity.ResultsAmong women without health conditions, AMA was associated with higher odds of PTB regardless of birthweight, LBW regardless of term, LBW term births, and LBW PTBs; stratified analysis showed higher risk of these outcomes among both older primiparas and multiparas. Compared with younger women with hypertensive disorders, older women with similar health conditions had higher odds of PTB regardless of birthweight. Older women with asthma had higher odds of LBW term births.ConclusionsAMA is associated with adverse birth outcomes among women with and without health conditions compared with younger women with similar health status. Improved screening and management of health conditions during pregnancy is needed for older women, regardless of parity.     

Low birthweight and prematurity in relation to paternal factors: a study of recurrence.

BACKGROUND: The importance of paternal determinants in the occurrence of low birthweight and prematurity is not well known. We investigated these outcomes in siblings and paternal half siblings as a function of changes in putative external determinants between two births in fathers who had experienced the birth of a premature and/or low birthweight (PTB/LBW) infant. METHODS: All fathers who, between 1980 and 1992, had an infant born before 37 completed weeks' gestation or weighing <2500 g and a following child were studied. We identified 14 147 pairs of siblings from Danish national registers. The recurrence risk was studied in three sub-cohorts defined by the outcome in the index child (PTB only, PTB/LBW, LBW only). We estimated the recurrence risk in the younger sibling according to changes of female partner, municipality type, occupation, and father's social status. RESULTS: The overall recurrence risk was 16.7% for preterm delivery and 16.8% for LBW. Changing female partner was, as expected, associated with a reduction in the recurrence risk for both outcomes (RR = 0.40; 95% CI: 0.27-0.60 for preterm delivery and RR = 0.38; 95% CI : 0.26-0.56 for LBW). None of the other studied factors was associated with changes in the recurrence risk. Fathers who changed partner had offspring with similar birthweight and gestational length between the three sub-cohorts, while a difference was evident in offspring to fathers whose female partner was unchanged. CONCLUSIONS: We did not identify any paternal factor of importance in the occurrence of LBW and preterm delivery.     

Estimating the Impact of Smoking Cessation During Pregnancy: The San Bernardino County Experience

We examined the relation between maternal smoking and adverse infant outcomes [low birth weight (LBW), and preterm birth (PTB)] during 2007–2008 in San Bernardino County, California—the largest county in the contiguous United States which has one of the highest rates of infant mortality in California. Using birth certificate data, we identified 1,430 mothers in 2007 and 1,355 in 2008 who smoked during pregnancy. We assessed the effect of never smoking and smoking cessation during pregnancy relative to smoking during pregnancy for the 1,843/1,798 LBW, and 3,480/3,238 PTB’s recorded for 2007/2008, respectively. To describe the effect of quitting smoking during pregnancy, we calculated the exposure impact number for smoking during pregnancy. Major findings are: (1) relative to smoking during pregnancy, significantly lower risk of LBW among never smoking mothers [OR, year: 0.56, 2007; 0.54, 2008] and for smoking cessation during pregnancy [0.57, 2007; 0.72, 2008]; (2) relative to smoking during pregnancy, significantly lower risk of PTB was found for never smoking mothers [0.68, 2007; 0.68, 2008] and for smoking cessation during pregnancy [0.69, 2007; 0.69, 2008]; (3) an exposure impact assessment indicating each LBW or PTB outcome in the county could have been prevented either by at least 35 mothers quitting smoking during pregnancy or by 25 mothers being never smokers during pre-pregnancy. Our findings identify an important burden of adverse infant outcomes due to maternal smoking in San Bernardino County that can be effectively decreased by maternal smoking cessation.     

Appalachian versus non-Appalachian U.S. traffic fatalities, 2008–2010

PurposeAlthough myriad health disparities exist in Appalachia, limited research has examined traffic fatalities in the region. This study compared traffic fatality rates in Appalachia and the non-Appalachian United States.MethodsFatality Analysis Reporting System and Census data from 2008 through 2010 were used to calculate traffic fatality rates. Poisson models were used to estimate unadjusted (rate ratio [RR]) and adjusted rate ratios, controlling for age, gender, and county-specific population density levels.ResultsThe Appalachian traffic fatality rate was 45% (95% confidence interval [CI], 1.42–1.47) higher than the non-Appalachian rate. Although only 29% of fatalities occur in rural counties in non-Appalachia versus 48% in Appalachia, rates in rural counties were similar (RR, 0.97; 95% CI, 0.95–1.00). However, the rate for urban, Appalachian counties was 42% (95% CI, 1.38–1.45) higher than among urban, non-Appalachian counties. Appalachian rates were higher for passenger vehicle drivers, motorcyclists, and all terrain vehicle riders, regardless of rurality, as well as for passenger vehicle passengers overall and for urban counties. Conversely, Appalachia experienced lower rates among pedestrians and bicyclists, regardless of rurality.ConclusionsDisparities in traffic fatality rates exist in Appalachia. Although elevated rates are partially explained by the proportion of residents living in rural settings, overall rates in urban Appalachia were consistently higher than in urban non-Appalachia.     

Incidence of and socio-demographic risk factors for stillbirth, preterm birth and low birthweight among Zimbabwean women

Data on birth outcomes are important for planning maternal and child health care services in developing countries. Only a few studies have examined frequency of birth outcomes in Zimbabwe, none of which has jointly examined the spectrum of poor birth outcomes across important demographic subgroups. We assessed delivery patterns and birth outcomes in 17 174 births over a one-year period from October 1997 to September 1998 at Harare Hospital, Zimbabwe. The annual rate of stillbirth was 61 per 1000 live births, rate of preterm birth (<37 weeks) was 168 per 1000, and low birthweight (LBW) (<2500 g) was 199 per 1000. Not attending antenatal care (prenatal care) was associated with increased risks of stillbirth [relative risk (RR) = 2.54, 95% CI 2.21, 2.92], preterm delivery [RR = 2.43, 95% CI 2.26, 2.61] and LBW births [RR = 2.16, 95% CI 2.02, 2.31]. Preterm births and LBW births were more likely to be stillborn [RR = 7.26, 95% CI 6.28, 8.39 and RR = 6.85, 95% CI 5.94, 7.91]. In conclusion, the rate of stillbirth is high and is predominantly associated with preterm births and to a lesser extent LBW. Reducing the frequency of stillbirth will require a better understanding of the determinants of preterm births and strategies for addressing this particular subset of high-risk births.     

Population attributable risk for adverse pregnancy outcomes related to smoking in adolescents and adults

BACKGROUND: Little is known about how population-attributable risks (PAR) for adverse birth outcomes due to smoking differ in adolescent and adult pregnancies. METHODS: An analysis of community and hospital-based cross-sectional studies in Liverpool was undertaken to estimate the PAR values of low birthweight (LBW), preterm birth, and small for gestational age (SGA) births resulting from pregnancy smoking covering the period between 1983 and 2003. Maternal smoking status and pregnancy outcomes were available for a sample of 12631 women. RESULTS: The prevalence of maternal pregnancy smoking was 40% in the community sample and 33% in adults and 40% among adolescent pregnancies in the hospital sample. The PAR values (95% CI) associated with LBW, preterm birth and SGA outcomes due to maternal pregnancy smoking in the community sample were 27% (25-30), 13% (11-15) and 25% (23-27), respectively. The PAR values in adults in the hospital sample were 29% (27-31) for LBW, 16% (14-19) for preterm birth and 28% (26-31) for SGA. The corresponding PAR values in adolescents were 39% (34-43), 12% (7-18) and 31% (23-40). The LBW risk attributed to pregnancy smoking in adolescents was significantly higher than for adults (P=0.05). CONCLUSION: About one-third of LBW, one-quarter of SGA and one-sixth of preterm births could be attributed to maternal smoking during pregnancy. The magnitude of the problem was greater among adolescent pregnancies, among whom a sub-group of mothers with very high risk for adverse birth outcomes due to pregnancy smoking was identified.     

Contextual effect of income inequality on birth outcomes

BACKGROUND: Though associations between income inequality and birth outcome have been suggested, mechanisms underlying this relationship are not known. In this analysis, we examined the relationship between income inequality and preterm birth (PTB) and post-neonatal mortality (PNM) to explore two potential mechanisms-the proposed psychosocial stress and neo-material pathways. METHODS: Data on singleton births from 1998 to 2000 were obtained from the CDC's National Center for Health Statistics' Linked Birth and Infant Death files. The Gini Index was utilized to measure income inequality and was divided into tertiles representing high, medium, and low county-level inequality. To determine the association between the birth outcomes and county income inequality and to account for clustering within counties, we employed generalized estimating equation (GEE) modelling. RESULTS: PTB increased from 8.3% in counties with low income inequality to 10.0% in counties with high inequality. The Gini Index remained modestly associated with PTB after adjusting for individual level variables and mean county-level per capita income within the total population (AOR: 1.06; 95% CI 1.03-1.09) as well as within most of the racial/ethnic groups. PNM increased from 1.15 deaths per 1000 live births in low inequality counties to 1.32 in high-inequality counties. However, after adjustment, income inequality was only associated with PNM within the non-Hispanic black population (AOR: 1.20; 95% CI 1.03-1.39). CONCLUSIONS: These findings may provide some support for the association between income inequality and PTB. Further research is required to elucidate the biological mechanisms of income inequality.     

中国低出生体重儿抽样调查结果

目的　调查全国活产儿出生体重情况和低出生体重儿发生率。方法　采用分层抽样方法 ,对中国 11个省的 16个市、2 8个县 ,1998年 7～ 10月出生的孕周≥ 2 8周的全部活产婴儿进行出生体重测查。结果　共测查活产儿 2 2 35 0人 (男 115 84人、女 10 76 6人 )。多胎率和早产率分别为 1 8%和 3 5 %。城市、农村和全国加权低出生体重儿发生率分别为 4 2 0 %、6 2 6 %和 5 87%。低出生体重儿中 6 1 2 %为足月儿 (≥ 37周 ) ,在农村则占 71 6 %。城市和农村活产儿平均出生体重分别为 330 1g和 32 2 5g,城市显著高于农村。男婴和女婴活产儿平均出生体重分别为 32 80g、3173g ,接近WHO推荐的出生体重均值。沿海、内地、边远地区活产儿平均出生体重呈逐渐下降趋势。低出生体重儿早期新生儿死亡率在城市为 5 0 0‰ ,农村为 179 4‰ ,全国为 15 1 5‰ ,显著高于正常出生体重婴儿。结论中国活产儿平均出生体重和低出生体重的发生率与发达国家水平接近 ,但地区间差异有显著性。低出生体重的主要原因是宫内发育迟缓 ,低出生体重儿的早期新生儿死亡率显著高于正常体重儿 ,应采取干预措施。     

Maternal obesity and diabetes as risk factors for adverse pregnancy outcomes: differences among 4 racial/ethnic groups

OBJECTIVES: We examined associations between obesity, diabetes, and 3 adverse pregnancy outcomes--primary cesarean delivery, preterm birth, and low birth-weight (LBW)--by racial/ethnic group. Our goal was to better understand how these associations differentially impact birth outcomes by group in order to develop more focused interventions. METHODS: Data were collected from the 1999, 2000, and 2001 New York City birth files for 329,988 singleton births containing information on prepregnancy weight and prenatal weight gain. Separate logistic regressions for 4 racial/ethnic groups predicted the adverse pregnancy outcomes associated with diabetes. Other variables in the regressions included obesity, excess weight gain, hypertension, preeclampsia, and substance use during pregnancy (e.g., smoking). RESULTS: Chronic and gestational diabetes were significant risks for a primary cesarean and for preterm birth in all women. Diabetes as a risk for LBW varied by group. For example, whereas chronic diabetes increased the risk for LBW among Asians, Hispanics, and Whites (adjusted odds ratios=2.28, 1.69, and 1.59), respectively, it was not a significant predictor of LBW among Blacks. CONCLUSIONS: In this large, population-based study, obesity and diabetes were independently associated with adverse pregnancy outcomes, highlighting the need for women to undergo lifestyle changes to help them control their weight during the childbearing years and beyond.     

Effects of Maternal Stress on Low Birth Weight and Preterm Birth Outcomes Across Neighborhoods of South Carolina, 2000–2003

Objective Studies evaluating the effect of maternal stress on preterm birth (PTB) or low birth weight (LBW) and variations across neighborhood contexts have been inconclusive. The purpose of the study was to examine the relationships among neighborhood contexts, prenatal stress, and birth outcomes, and to further explore the modifying effects of neighborhood contexts. Methods We evaluated this objective by using South Carolina Pregnancy Risk Assessment and Monitoring System (PRAMS), 2000–2003 data linked to the 2000 U.S. census data for 8064 women (N = 8064). Principal component analysis with varimax rotation was used to group stress constructs into four main domains (Financial, Emotional, Traumatic, and Spousal-related). We used multilevel logistic regression analysis to estimate the adjusted odds ratio for different models. Results Maternal stress was significantly associated with increased risks of low birth weight and preterm deliveries. Neighborhood high poverty and low education (upper quartiles) were independently associated with low birth weight but not preterm deliveries and stress appeared as a partial mediator of contextual effects on birth outcomes. The interaction models showed that the relationship between stress and LBW or PTB was modified by neighborhood contexts with risks being greater for infants born in disadvantaged neighborhoods. Conclusions Effects of maternal stress on LBW and PTB outcomes may be different for mothers living in different neighborhood contexts. Therefore, investigations that fail to examine places of residence would most likely not identify mothers at risk of LBW or PTB. Policies to improve birth outcomes need to target both places of residence and specific mediating or moderating factors associated with deprived neighborhoods of residence.     

A Bayesian growth mixture model to examine maternal hypertension and birth outcomes

Maternal hypertension is a major contributor to adverse pregnancy outcomes, including preterm birth (PTB) and low birth weight (LBW). Although several studies have explored the relationship between maternal hypertension and fetal health, few have examined how the longitudinal trajectory of blood pressure, considered over the course of pregnancy, affects birth outcomes. In this paper, we propose a Bayesian growth mixture model to jointly examine the associations between longitudinal blood pressure measurements, PTB, and LBW. The model partitions women into distinct classes characterized by a mean arterial pressure (MAP) curve and joint probabilities of PTB and LBW. Each class contains a unique mixed effects model for MAP with class-specific regression coefficients and random effect covariances. To account for the strong correlation between PTB and LBW, we introduce a bivariate probit model within each class to capture residual within-class dependence between PTB and LBW. The model permits the association between PTB and LBW to vary by class, so that for some classes, PTB and LBW may be positively correlated, whereas for others, they may be uncorrelated or negatively correlated. We also allow maternal covariates to influence the class probabilities via a multinomial logit model. For posterior computation, we propose an efficient MCMC algorithm that combines full-conditional Gibbs and Metropolis steps. We apply our model to a sample of 1027 women enrolled in the Healthy Pregnancy, Healthy Baby Study, a prospective cohort study of host, social, and environmental contributors to disparities in pregnancy outcomes.