The racial disparity of severe maternal morbidity across weeks of gestation: a cross-sectional analysis of the 2019 National Inpatient Sample.

BACKGROUND: Severe maternal morbidity is increasing in the United States. Black women experience the highest rates of severe maternal morbidity and also of preterm births, which are associated with severe maternal morbidity. The racial disparity of severe maternal morbidity across weeks of gestation has not been well-studied. OBJECTIVE: This study aimed to evaluate differences in severe maternal morbidity between Black and White birthing people by week of gestation. Differences may indicate periods of pregnancy when Black women are particularly vulnerable to severe maternal morbidity and may require additional interventions. STUDY DESIGN: This was a cross-sectional study using the National Inpatient Sample from 2019. We used International Classification of Diseases codes from Centers for Disease Control and Prevention guidelines to identify severe maternal morbidity from delivery hospitalizations. We examined the rates of severe maternal morbidity in Black vs White women by week of gestation to evaluate periods of pregnancy when Black women experience additional risks of severe maternal morbidity while adjusting for age, region, medical comorbidities, and Medicaid enrollment. Severe maternal morbidity was analyzed while both including and excluding cases for which blood transfusion was the only indicator of severe maternal morbidity. RESULTS: Overall, Black birthing people had twice the rate of severe maternal morbidity births compared with White birthing people (2.7% vs 1.3%; P<.0001) and were more likely to deliver preterm (14.7% vs 9.4%; P<.0001). The racial disparity of severe maternal morbidity was present throughout all weeks of gestation, with the largest gap observed at extremely and moderately preterm gestations (22-33 weeks). Rates of severe maternal morbidity for Black women peaked at 22 to 33 weeks' gestation and were lowest at term (≥37 weeks). Black women had a greater proportion of severe maternal morbidity cases due to blood transfusion (68.3% vs 64.5%; P<.01) and acute renal failure (11.1% vs 8.5%; P<.001). CONCLUSION: Black women experience a substantially higher rate of severe maternal morbidity at preterm gestations (22-36 weeks) in addition to higher rates of preterm delivery. Even when accounting for age, medical comorbidities, and social determinants, Black birthing people have higher odds of severe maternal morbidity throughout pregnancy.

Crossing Birth-Weight-Specific Mortality Curves: How a Puzzling Clinical Observation Led to an Important Advance in Epidemiologic Methods.

Throughout the second half of the 20th century, clinicians noted that although African-American neonates were more likely than White neonates to weigh less than 2,500 g at birth (low birth weight), among low-birth-weight infants African Americans were more likely than Whites to survive. However, when born at normal weight, African-American infants were substantially less likely to survive. The observation generated much physiological speculation, and several clever mathematical manipulations were devised to "uncross the mortality curves." With the development and dissemination of directed acyclic graphs in the early 2000s, methodologists focusing on perinatal epidemiology showed graphically, in an early use of directed acyclic graphs, that birth weight was a "collider" and that controlling for birth weight, whether by regression, stratification, or restriction, introduced confounding of the race-mortality association by all unmeasured common causes of birth weight and mortality. These investigations showed that the crossing curves could be explained as an artifact of a conceptually flawed analysis. These results have applicability beyond perinatal epidemiology, including applicability to the "obesity paradox."

Early childhood growth trajectories in a Medicaid population.

BACKGROUND: Evidence on the role of early growth trajectories and later obesity risk is primarily based on privately insured or universally insured samples. OBJECTIVES: We aimed to characterize and determine factors associated with early growth trajectories and estimate associations with overweight/obesity risk in a Medicaid-insured and uninsured cohort. METHODS: Infants seen at a large pediatric academic centre in 2010-2016 were included. Weight and length/height measurements were converted to age and sex-specific BMI z-scores (BMIz) based on the World Health Organization (WHO) Growth Standards. Group-based trajectories were modelled using BMIz created groups. Logistic and log-binomial regression models estimated associations between membership in trajectories and maternal/child factors and overweight or obesity at 36, 48, and 60 months, separately. Analyses were performed between 2019 and 2021. RESULTS: The best-fitting model identified five BMIz trajectories among 30 189 children and 310 113 clinical encounters; two trajectories showed rapid rise in BMIz. Lower maternal education, pre-pregnancy maternal overweight/obese status, and maternal smoking were positively associated with both rapid-rising BMIz trajectories. Children in either of the two rapid-rising trajectories were 3.00 (95% CI: 2.85, 3.25), 2.97 (95% CI: 2.77, 3.18) and 2.76 (95% CI: 2.53, 3.01) times more likely to have overweight or obesity at 36, 48, and 60 months, respectively compared to children in the stable trajectory groups. CONCLUSIONS: Among Medicaid insured and uninsured children, several maternal and child characteristics were associated with early rapid-rise in BMIz. Clinical monitoring of early rapidly rising BMI may be important to address modifiable risk factors for obesity in families from low-income households.

Epidemiology: Back to the Future.

In 2018, the Society for Epidemiologic Research and its partner journal, the American Journal of Epidemiology, assembled a working group to develop a set of papers devoted to the "future of epidemiology." These 14 papers covered a wide range of topic areas and perspectives, from thoughts on our profession, teaching, and methods to critical areas of substantive research. The authors of those papers considered current challenges and future opportunities for research and education. In light of past commentaries, 4 papers also include reflections on the discipline at present and in the future.

Good practices for the design, analysis, and interpretation of observational studies on birth spacing and perinatal health outcomes.

BACKGROUND: Meta-analyses of observational studies have shown that women with a shorter interpregnancy interval (the time from delivery to start of a subsequent pregnancy) are more likely to experience adverse pregnancy outcomes, such as preterm delivery or small for gestational age birth, than women who space their births further apart. However, the studies used to inform these estimates have methodological shortcomings. METHODS: In this commentary, we summarise the discussions of an expert workgroup describing good practices for the design, analysis, and interpretation of observational studies of interpregnancy interval and adverse perinatal health outcomes. RESULTS: We argue that inferences drawn from research in this field will be improved by careful attention to elements such as: (a) refining the research question to clarify whether the goal is to estimate a causal effect vs describe patterns of association; (b) using directed acyclic graphs to represent potential causal networks and guide the analytic plan of studies seeking to estimate causal effects; (c) assessing how miscarriages and pregnancy terminations may have influenced interpregnancy interval classifications; (d) specifying how key factors such as previous pregnancy loss, pregnancy intention, and maternal socio-economic position will be considered; and (e) examining if the association between interpregnancy interval and perinatal outcome differs by factors such as maternal age. CONCLUSION: This commentary outlines the discussions of this recent expert workgroup, and describes several suggested principles for study design and analysis that could mitigate many potential sources of bias.

Progression of care among women who use a midwife for prenatal care: Who remains in midwife care?

BACKGROUND: Prenatal care provided by midwives provides a safe and cost-effective alternative to care provided by physicians. However, no studies have evaluated the frequency of women who leave midwifery care, in a hospital setting. Our study objectives were to measure the frequency of transfers of care to physicians, to describe the sociodemographic and pregnancy-related characteristics of women who transferred to the care of a physician during prenatal care and at delivery, and to assess correlates of these transfers. METHODS: We used electronic medical records to perform a retrospective cohort study of women who delivered at The Ohio State University Wexner Medical Center (OSUWMC) and had at least one prenatal care visit within OSUWMC's network. We report descriptive findings, using proportions and means with standard deviations. We used logistic regression, with Firth's bias correction as necessary, to assess correlates of transferring to a physician during prenatal care and at delivery. RESULTS: Most women who initiated prenatal care with a midwife remained in midwifery care throughout delivery, with 4.7% transferring to a physician during prenatal care, and an additional 21.4% transferring to a physician during delivery. After adjusting for pregnancy-related factors, the black race was statistically significantly associated with leaving midwifery care during prenatal care (adjusted odds ratio AOR 3.0 [95% CI 1.4-6.6]) and delivery (AOR 2.5 [95% CI 1.5-4.3]). CONCLUSION: Findings indicate that most women remain in midwifery care throughout pregnancy, but raise important questions with respect to the possible role that race has in pregnancy care.

The epidemiology, etiology, and costs of preterm birth.

After decades of rising preterm birth rates in the USA and other countries, recent prematurity rates seem to be on the decline. Despite this optimistic trend, preterm birth rates remain higher in the USA, where nearly one in every eight infants is born early, compared to other developed countries. The prevention of preterm birth is considered a public health priority because of the potential to reduce infant and childhood morbidity and mortality related to this condition. Unfortunately, progress has been modest. One of the greatest challenges in studying this outcome is that preterm birth is a complex condition resulting from multiple etiologic pathways. Recently, experts have developed innovative frameworks for classifying and studying preterm birth based on phenotype. These proposed classification systems have only recently been adopted, but a different perspective on a longstanding problem has the potential to lead to new discoveries.

Trends and factors associated with self-reported receipt of preconception care: PRAMS, 2004-2010.

BACKGROUND: Preconception care (PCC) is a form of primary prevention for promoting health, assessing risk, and intervening to modify risk factors to try to improve maternal and infant outcomes. Clinical provision of preconception care before and after the release of recommendations has not been evaluated. Our objective was to determine trends in self-reported receipt of PCC from 2004 to 2010, and factors associated with self-reported receipt of PCC. METHODS: Pregnancy Risk Assessment Monitoring System (PRAMS) data from 12 states were used to determine trends in PCC. Weighted multivariable logistic regression was used to identify factors associated with self-reported receipt of PCC. RESULTS: The sample consisted of n = 64,084 women, with 30.8 percent reporting receipt of PCC. PCC increased from 30.3 percent in 2004 to 32.6 percent in 2010 (p = 0.08 for trend). Women who were younger, with lower household income, or with a preterm birth were less likely to report PCC. Women with lower levels of education, who were non-Hispanic black, intending pregnancy, without previous children, or with prepregnancy government insurance were more likely to report PCC. CONCLUSIONS: Only one-third of women with a recent live birth report receipt of any PCC. There is a need to increase PCC receipt, especially among populations that demonstrate lower levels.

Maternal vitamin D status and the risk of mild and severe preeclampsia.

BACKGROUND: We sought to determine the association between maternal vitamin D status at ≤26 weeks' gestation and the risk of preeclampsia by clinical subtype. METHODS: We conducted a case-cohort study among women enrolled at 12 US sites from 1959 to 1966 in the Collaborative Perinatal Project. In serum collected at ≤26 weeks' gestation (median 20.9 weeks) from 717 women who later developed preeclampsia (560 mild and 157 severe cases) and from 2986 mothers without preeclampsia, we measured serum 25-hydroxyvitamin D, over 40 years later, using liquid chromatography-tandem mass spectrometry. RESULTS: Half of women in the subcohort had 25-hydroxyvitamin D (25(OH)D) >50 nmol/L. Maternal 25(OH)D 50 to 74.9 nmol/L was associated with a reduction in the absolute and relative risk of preeclampsia and mild preeclampsia compared with 25(OH)D <30 nmol/L in the crude analysis but not after adjustment for confounders, including race, prepregnancy body mass index, and parity. For severe preeclampsia, 25(OH)D ≥50 nmol/L was associated with a reduction in three cases per 1000 pregnancies (adjusted risk difference = -0.003 [95% confidence interval = -0.005 to 0.0002]) and a 40% reduction in risk (0.65 [0.43 to 0.98]) compared with 25(OH)D <50 nmol/L. Conclusions were unchanged (1) after restricting to women with 25(OH)D measured before 22 weeks' gestation or (2) with formal sensitivity analyses for unmeasured confounding. CONCLUSIONS: Maternal vitamin D deficiency may be a risk factor for severe preeclampsia but not for its mild subtypes. Contemporary cohorts with large numbers of severe preeclampsia cases would be needed to confirm or refute these findings.