Identifying Multiple Risks of Low Birth Weight Using Person-Centered Modeling

Pregnancy with multiple high-risk factors: a systematic review and meta-analysis

Background

A wide spectrum of high-risk factors in pregnancy can lead to adverse pregnancy outcomes or short- or long-term health effects. Despite this, there has been no synthesis of findings on the measurement, potential causes, and health outcomes of multiple high-risk factors in pregnancy (MHFP). We aimed to address this gap by summarising the existing research on this topic.

Methods

We retrieved studies published up to 3 June 2024 through systematic database searches and used a narrative synthesis approach to summarise the measurement, patterns, causes, and outcomes of MHFP. We also estimated the pooled MHFP prevalence through meta-analysis with a random effects model and performed subgroup analyses and meta-regression to examine potential sources of between-study heterogeneity.

Results

We included 83 observational studies published between 2010 and 2024, of which 72% were from high-income countries. These studied factors can be grouped into four categories: physical conditions, mental conditions, sociobehavioural problems, and pregnancy history. We identified 16 MHFP patterns, among which co-existing multiple physical conditions were the most common pattern. The overall pooled prevalence of MHFP was 12% (95% confidence interval (CI) = 12-13), with an increasing trend and relatively higher levels in low- and middle-income countries (LMICs). We observed heterogeneity in the measurement of MHFP across the studies, possibly due to the number of risk factors in the definition of MHFP. About 78% of included studies investigated MHFP-associated health outcomes for women and offspring, with only two studies examining long-term maternal or offspring outcomes later in life.

Conclusions

Research into MHFP has been emerging over the past decade, but is far from complete. The burden of MHFP is increasing worldwide, particularly LMICs. Maternal healthcare systems must shift to a multidisciplinary and integrated framework so as to better design and implement prevention and intervention programmes and sustain the healthy development of the next generation.

Registration

PROSPERO: CRD42022358889.

Associations between prenatal exposure to phthalates and birth weight: A meta-analysis study

Previous studies have suggested that phthalates are associated with birth weight. However, most phthalate metabolites have not been fully explored. Therefore, we conducted this meta-analysis to assess the relationship between phthalate exposure and birth weight. We identified original studies that measured phthalate exposure and reported its association with infant birth weight in relevant databases. Regression coefficients (β) with 95% confidence intervals (CIs) were extracted and analyzed for risk estimation. Fixed-effects (I² ≤ 50%) or random-effects (I² > 50%) models were adopted according to their heterogeneity. Overall summary estimates indicated negative associations of prenatal exposure to mono-n-butyl phthalate (pooled β = -11.34 g; 95% CI: -20.98 to -1.70 g) and mono-methyl phthalate (pooled β = -8.78 g; 95% CI: -16.30 to -1.27 g). No statistical association was found between the other less commonly used phthalate metabolites and birth weight. Subgroup analyses indicated that exposure to mono-n-butyl phthalate was associated with birth weight in females (β = -10.74 g; 95% CI: -18.70 to -2.79 g). Our findings indicate that phthalate exposure might be a risk factor for low birth weight and that this relationship may be sex specific. More research is needed to promote preventive policies regarding the potential health hazards of phthalates.

Sociodemographic patterns of preterm birth and low birth weight among pregnant women in rural Mysore district, India: A latent class analysis

Few studies have utilized person-centered approaches to examine co-occurrence of risk factors among pregnant women in low-and middle-income settings. The objective of this study was to utilize latent class analysis (LCA) to identify sociodemographic patterns and assess the association of these patterns on preterm birth (PTB) and/or low birth weight (LBW) in rural Mysore District, India. Secondary data analysis of a prospective cohort study among 1540 pregnant women was conducted. Latent class analysis was performed to identify distinct group memberships based on a chosen set of sociodemographic factors. Binary logistic regression was conducted to estimate the association between latent classes and preterm birth and low birth weight. LCA yielded four latent classes. Women belonging to Class 1 "low socioeconomic status (SES)/early marriage/multigravida/1 child or more", had higher odds of preterm birth (adjusted Odds Ratio (aOR): 95% Confidence Intervals (CI): 1.77, 95% CI: 1.05-2.97) compared to women in Class 4 "high SES/later marriage/primigravida/no children". Women in Class 2 "low SES/later marriage/primigravida/no children" had higher odds of low birth weight (aOR: 2.52, 95% CI: 1.51-4.22) compared to women in Class 4. Women less than 20 years old were twice as likely to have PTB compared to women aged 25 years and older (aOR: 2.00, 95% CI: 1.08-3.71). Hypertension (>140/>90 mm/Hg) was a significant determinant of PTB (aOR: 2.28, 95% CI: 1.02-5.07). Furthermore, women with a previous LBW infant had higher odds of delivering a subsequent LBW infant (aOR: 2.15, 95% CI: 1.40-3.29). Overall study findings highlighted that woman belonging to low socioeconomic status, and multigravida women had increased odds of preterm birth and low birth weight infants. Targeted government programs are crucial in reducing inequalities in preterm births and low birth weight infants in rural Mysore, India.

Predictors of preterm birth and low birth weight: A person-centered approach

Objective

Profound disparities exist among Black and White families who experience adverse infant health outcomes, yet much is unclear regarding factors that predict disparate outcomes. In order to address this gap, this study applied a person-centered, intersectional analysis to determine ways that women's typological risk profiles inform risk for preterm birth and low birth weight.

Materials and methods

In order to examine the role that social determinants play in predicting risk, this study implemented a latent class mixture modeling analysis of data from the Pregnancy Risk Assessment Monitoring System (PRAMS). Data were extracted from Pennsylvania and Illinois PRAMS surveys from 2012 to 2015 (n = 4336).

Results

Results of the study indicate three distinct risk types among women in the sample: low-, moderate- and high-risk. Three latent classes were identified: (1) low risk for PTB/LBW (44%); (2) moderate risk (19%); and (3) high risk (36%). Compared to class one, the likelihood of experiencing PTB were significantly higher for class three (x²_PTB = 9.54, p < .001; x²_LBW = 35.51, p < .001). The likelihood of experiencing LBW were significantly higher for class three, compared to class two (x²_PTB = 9.21, p < .05; x²_LBW = 21.17, p < .001).Within the three risk groups, racial disparities are particularly notable, with 76% of the sample's African American mothers falling into the “high-risk” category.

Conclusion

Public and perinatal health researchers, organizations, and funders are increasingly recognizing the need to identify methods that will best support health-promoting interventions that have the potential to close the racial disparity in PTB and LBW. Although racial disparities have long been noted, the findings from this study's analysis help to better understand how determinants of health intersect to create an overarching risk profile, which can be used to inform health interventions and services that may reduce the current Black-White gap in infant health outcomes.

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Profound race-based infant health disparities exist, yet much is unclear regarding factors that predict disparate outcomes.

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Disparities-related science has largely neglected theoretical models that could help conceptualize this complex issue.

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This article drew from a comprehensive theoretical framework to investigate disparities in infant health outcomes.

To What Extent Is the Association Between Race/Ethnicity and Fetal Growth Restriction Explained by Adequacy of Prenatal Care? A Mediation Analysis of a Retrospectively Selected Cohort

Race/ethnicity is associated with intrauterine growth restriction (IUGR) and small-for-gestational age (SGA) birth. We evaluated the extent to which this association is mediated by adequacy of prenatal care (PNC). A retrospective cohort study was conducted using US National Center for Health Statistics natality files for the years 2011-2017. We performed mediation analyses using a statistical approach that allows for exposure-mediator interaction, and we estimated natural direct effects, natural indirect effects, and proportions mediated. All effects were estimated as risk ratios. Among 23,118,656 singleton live births, the excess risk of IUGR among Black women, Hispanic women, and women of other race/ethnicity as compared with White women was partly mediated by PNC adequacy: 13% of the association between non-Hispanic Black race/ethnicity and IUGR, 12% of the association in Hispanic women, and 10% in other women was attributable to PNC inadequacy. The percentage of excess risk of SGA birth that was mediated was 7% in Black women, 6% in Hispanic women, and 5% in other women. Our findings suggest that PNC adequacy may partly mediate the association between race/ethnicity and fetal growth restriction. In future research, investigators should employ causal mediation frameworks to consider additional factors and mediators that could help us better understand this association.

Latent Class Analysis of Low Birth Weight and Preterm Delivery among Australian Women

OBJECTIVES

To identify patterns of health, socioeconomic, behavioral, and psychosocial indicators that may be associated with low birth weight delivery or preterm birth.

STUDY DESIGN

Data were analyzed from the Australian Longitudinal Study on Women's Health. A total of 9075 live singleton births among 3801 women were linked to state perinatal records with birth outcome data. Survey data were used to identify 11 indicators for latent class analysis. Latent classes were tested for association to birth outcomes. These indicators also were used along with covariates in main effect multiple logistic regression analyses of birth outcomes.

RESULTS

Latent class analysis revealed 5 classes, including those characterized by low education, recent drug use, stress/anxiety/depression, smoking/drinking/low education/multi-risk, and a low risk referent group. The stress/anxiety/depression class was associated with preterm delivery (OR 1.87, 95% CI 1.20-2.92), and the smoking/drinking/low education/multirisk class was associated with low birth weight (OR 1.54, 95% CI 1.02-2.30). Traditional logistic regression analyses for main effects identified some measures not captured by the latent classes, and the latent classes identified variable combinations not captured by the main effect analysis.

CONCLUSIONS

Unique latent classes were associated with preterm delivery vs low birth weight. Both latent class analysis and main effects analyses may be combined to improve understanding of birth outcome risks. Clinical and programmatic interventions to reduce risks of low birth weight and preterm delivery may benefit from risk profiles that women experience.

Medical and Psychosocial Risk Profiles for Low Birthweight and Preterm Birth

OBJECTIVES

Low birthweight and preterm birth are risk factors for infant mortality and persistent problems. This study uses representative data to assess whether distinct latent profiles of co-occurring medical and psychosocial factors have implications for preterm birth and low birthweight.

METHODS

Data are from the Pregnancy Risk Assessment Monitoring System, a cross-sectional survey constituting representative data on pregnancies from 2012 to 2013. Latent class analysis derived classes of pregnant women potentially at risk for low birthweight and/or preterm birth.

RESULTS

Latent class analysis identified five homogenous profiles of interrelated psychosocial and medical factors. Risk was greatest for the profile marked by high rates of medical factors, followed by a high risk for a profile marked by a combination of very low income and psychosocial factors. Two profiles involving low income and very low income also indicated greater risk for adverse birth outcomes related to socioeconomic status.

CONCLUSIONS

More attention should be paid to screening for and addressing psychosocial risk in concert with prenatal care. Women who show high-risk profiles can be monitored and supported by an interdisciplinary care team, when warranted.

Latent class analysis of the association between polycyclic aromatic hydrocarbon exposures and body mass index

BACKGROUND

People experience multiple co-occurring exposures to environmental pollutants, but analyses of multiple exposures have rarely been reported.

OBJECTIVES

We used latent class analysis to estimate co-exposures to multiple polycyclic aromatic hydrocarbons (PAH), and tested the associations of latent classes to body mass index.

METHODS

We analyzed National Health and Nutrition Examination Survey (NHANES) 2013-2014 data. The sample included 2354 people aged 6-80 years. Measures included seven urinary PAH metabolites, BMI, and demographic and behavioral covariates. People were classified into mutually exclusive latent classes characterized by unique profiles of multiple PAH exposures. These classes were used as categorical independent variables in weighted multiple regression models with BMI as the dependent measure. Models were analyzed overall and by age groups (6-19, 20-59, and 60 and over.) We compared results using latent classes to results using a summed PAH exposure measure.

RESULTS

Five latent classes were identified. Two of these classes were significantly associated with higher BMI overall (p < .0001) and for the two youngest age groups. One of these classes was characterized by high multiple exposures across all PAHs, and one by moderate exposures but relatively high naphthalene and phenanthrene. The summed PAH score was associated with higher BMI only for the youngest age group.

CONCLUSIONS

Persons experience multiple co-exposures to PAHs that are related to BMI and obesity across age groups. Latent class analysis provides information on higher order interactions among multiple chemicals that a summed score does not. Future work may apply this approach to other outcomes or types of co-exposures.

Profiles of Contextual Risk at Birth and Adolescent Substance Use

This study examined whether there are subgroups of families with distinct profiles of prenatal/birth contextual risk, and whether subgroup membership was differentially related to adolescent substance use. Data from the Northern Finland Birth Cohort 1986 were used. A five-class model provided the most meaningful solution. Large Family Size (7.72%) and Low Risk (69.69%) groups had the lowest levels of alcohol, cigarette, and illegal drug use. Similar high levels for each of the three substance-related outcomes were found for Parent Substance Misuse (11.20%), Maternal School Dropout (4.66%), and Socioeconomic Disadvantage (6.72%) groups. Maternal smoking and drinking while pregnant and paternal heavy alcohol use were found to be key prenatal risk factors that tended to cluster together and co-occur with other prenatal risk factors differently for different subgroups of youth.

Evaluation of Health in Pregnancy grants in Scotland: a natural experiment using routine data

Background

Pregnancy and the period around birth are critical for the development and improvement of population health as well as the health of mothers and babies, with outcomes such as birthweight influencing adult health.

Objectives

We evaluated the clinical effectiveness and cost-effectiveness of the Health in Pregnancy (HiP) grants in Scotland, looking for differential outcomes when the scheme was in place, as well as before its implementation and after its withdrawal.

Design

The HiP grants were evaluated as a natural experiment using interrupted time series analysis. We had comparison groups of women who delivered before the grants were introduced and after the grants were withdrawn.

Setting

Scotland, UK.

Participants

A total of 525,400 singleton births delivered between 24 and 44 weeks in hospitals across Scotland between 1 January 2004 and 31 December 2014.

Intervention

The HiP grant was a universal, unconditional cash transfer of £190 for women in Great Britain and Northern Ireland reaching 25 weeks of pregnancy if they had sought health advice from a doctor or midwife. The grant was introduced for women with a due date on or after 6 April 2009 and subsequently withdrawn for women reaching the 25th week of pregnancy on or after 1 January 2011. The programme was paid for by Her Majesty’s Treasury.

Main outcome measures

Our primary outcome measure was birthweight. Secondary outcome measures included maternal behaviour, measures of size, measures of stage and birth outcomes.

Data sources

The data came from the Scottish maternity and neonatal database held by the Information and Services Division at the NHS National Services Scotland.

Results

There was no statistically significant effect on birthweight, with births during the intervention period being, on average, 2.3 g [95% confidence interval (CI) –1.9  to 6.6 g] lighter than would have been expected had the pre-intervention trend continued. Mean gestational age at booking (i.e. the first antenatal appointment with a health-care professional) decreased by 0.35 weeks (95% CI 0.29 to 0.41 weeks) and the odds of booking before 25 weeks increased by 10% [odds ratio (OR) 1.10, 95% CI 1.02 to 1.18] during the intervention but decreased again post intervention (OR 0.91, 95% CI 0.83 to 1.00). The odds of neonatal death increased by 84% (OR 1.84, 95% CI 1.22 to 2.78) and the odds of having an emergency caesarean section increased by 7% (OR 1.07, 95% CI 1.03 to 1.10) during the intervention period.

Conclusions

The decrease in the odds of booking before 25 weeks following withdrawal of the intervention makes it likely that the HiP grants influenced maternal health-care-seeking behaviour. It is unclear why neonatal mortality and emergency caesarean section rates increased, but plausible explanations include the effects of the swine flu outbreak in 2009 and the global financial crisis. The study is limited by its non-randomised design. Future research could assess an eligibility threshold for payment earlier than the 25th week of pregnancy.

Funding

The National Institute for Health Research Public Health Research programme. The Social and Public Health Sciences Unit is core funded by the Medical Research Council (MC_UU_12017/13) and the Scottish Government Chief Scientist Office (SPHSU13).

Exploring the Psychosocial Predictors of Gestational Diabetes and Birth Weight

OBJECTIVE

To determine the best sociodemographic and behavioral predictors for gestational diabetes mellitus (GDM) and birth weight (BW) and whether stress, depression, or abuse influences GDM and BW after controlling for sociodemographic variables.

DESIGN

Retrospective correlational.

SETTING

Utah Pregnancy Risk Monitoring System and birth certificate data.

PARTICIPANTS

We analyzed data from the birth certificates of 4,682 women with live births between 2009 and 2011 in Utah. During that time, a total of 143,373 live births occurred in the state. Data were predominantly from non-Hispanic White, married, or partnered women with average age of 27.5 years and average body mass index (BMI) of 25.1.

METHODS

Stress, cumulative depression, and abuse were operationalized based on previous analysis, and control and covariate data (e.g., age, BMI, race, ethnicity, education, marital status) were collected. Bivariate analysis was used to identify associations between variables, and a hierarchical stepwise logistical regression was conducted to identify best predictors of GDM and BW.

RESULTS

We did not find that cumulative depression, stress, or abuse was a predictor of GDM, and only cumulative stress was a predictor of BW. More incidences of GDM were observed in women who were poor, older, less educated, non-White, obese, or experienced depression during pregnancy.

CONCLUSION

Unlike depression or abuse, stress is often overlooked by providers. This finding represents an unmet opportunity for nurses to screen for and assist women with stressors to positively affect birth weight.

Evaluation of health in pregnancy grants in Scotland: a protocol for a natural experiment

INTRODUCTION

A substantial proportion of low birth weight is attributable to the mother's cultural and socioeconomic circumstances. Early childhood programmes have been widely developed to improve child outcomes. In the UK, the Health in Pregnancy (HiP) grant, a universal conditional cash transfer of £190, was introduced for women reaching the 25th week of pregnancy with a due date on/or after 6 April 2009 and subsequently withdrawn for women reaching the 25th week of pregnancy on/or after 1 January 2011. The current study focuses on the evaluation of the effectiveness and cost-effectiveness of the HiP grant.

METHODS AND ANALYSIS

The population under study will be all singleton births in Scotland over the periods of January 2004 to March 2009 (preintervention), April 2009 to April 2011 (intervention) and May 2011 to December 2013 (postintervention). Data will be extracted from the Scottish maternity and neonatal database. The analysis period 2004-2013 should yield over 585,000 births. The primary outcome will be birth weight among singleton births. Other secondary outcomes will include gestation at booking, booking before 25 weeks; measures of size and stage; gestational age at delivery; weight-for-dates, term at birth; birth outcomes and maternal smoking. The main statistical method we will use is interrupted time series. Outcomes will be measured on individual births nested within mothers, with mothers themselves clustered within data zones. Multilevel regression models will be used to determine whether the outcomes changed during the period in which the HiP grants was in effect. Subgroup analyses will be conducted for those groups most likely to benefit from the payments.

ETHICS AND DISSEMINATION

Approval for data collection, storage and release for research purpose has been given (6 May 2014, PAC38A/13) by the Privacy Advisory Committee. The results of this study will be disseminated through peer-reviewed publications in journals, national and international conferences.