Contribution of maternal cardiometabolic risk factors to racial-ethnicity disparities in preterm birth subtypes.

There are recognized racial-ethnic disparities in preterm birth and in maternal cardiometabolic risk factors likely linked to systemic racism. However, it is unclear the extent to which cardiometabolic risk factors contribute to the higher rates of preterm birth among minoritized populations. This study aimed to evaluate racial-ethnic disparities in preterm birth subtypes and the role of maternal cardiometabolic risk factors as mediators of the association between maternal race-ethnicity and preterm birth subtypes. This was a retrospective cohort study of 295,210 singleton live births from 2011 to 2018. Preterm birth subtypes were defined as medically indicated and spontaneous preterm birth. Poisson regression with robust standard errors were used to provide estimates of the relative risks and 95% confidence intervals for preterm birth subtypes. Causal mediation analysis used logistic regression models to estimate the natural direct and natural indirect (mediated) effects of maternal cardiometabolic risk factors. Compared with White individuals, Black, Asian, and Hispanic individuals were at increased risk for having both medically indicated preterm birth (1.45, 1.30-1.61; 1.21, 1.12-1.31; and 1.13, 1.05-1.22, respectively) (risk ratios, 95% confidence intervals, respectively) and spontaneous preterm birth (1.20, 1.08-1.34; 1.34, 1.26-1.43; and 1.16, (1.08-1.23), independent of established risk factors. The extent to which cardiometabolic risk factors mediated the associations between race-ethnicity (each group vs White in separate analyses) and preterm birth subtypes varied by race-ethnicity. Hypertensive disorders mediated 30.1% of the association between Black race-ethnicity and medically indicated preterm birth, but it did not mediate the association for other racial-ethnic groups or for spontaneous preterm birth. Any glucose disorder in pregnancy was a mediator of medically indicated preterm birth and spontaneous preterm birth for Asian (65.8% and 13.9%, respectively) and Hispanic (17.3% and 11.9%) race-ethnicity but not for Black race-ethnicity. Overweight or obesity mediated the association between race-ethnicity and medically indicated preterm birth (15.5% among Black individuals and 25.1% among Hispanic individuals) and spontaneous preterm birth (10.7% among Hispanic individuals) but was not a mediator among Asian individuals. Black, Asian, and Hispanic individuals are at increased risk for preterm birth. Maternal cardiometabolic risk factors partially mediate the associations between race-ethnicity and preterm birth subtypes but the extent varies by race-ethnicity. These findings suggest that strategies that improve and diminish differences in cardiometabolic health between race-ethnicity populations may diminish disparities in preterm birth.

Hedderson MM ，Xu F ，Dayo OM ，Liu E ，Sridhar S ，Lee C ，Greenberg M ... -  《-》

The interaction between maternal race/ethnicity and chronic hypertension on preterm birth.

In both the biomedical and public health literature, the risk for preterm birth has been linked to maternal racial/ethnic background, in particular African-American heritage. Despite this well-documented health disparity, the relationship of comorbid conditions, such as chronic hypertension, to maternal race/ethnicity and preterm birth has received relatively limited attention in the literature. The objective of the study was to evaluate the interaction between chronic hypertension and maternal racial/ethnic background on preterm birth. This is a retrospective cohort study of singleton pregnancies among women who delivered between 2002 and 2015 at the University of California, San Francisco. The associations of chronic hypertension with both spontaneous and medically indicated preterm birth were examined by univariate and multivariate logistical regression, adjusting for confounders including for maternal age, history of preterm birth, maternal body mass index, insurance type (public vs private), smoking, substance abuse, history of pregestational diabetes mellitus, and use of assisted reproductive technologies. The interaction effect of chronic hypertension and racial/ethnicity was also evaluated. All values are reported as odds ratios, with 95% confidence intervals and significance set at P = .05. In this cohort of 23,425 singleton pregnancies, 8.8% had preterm deliveries (3% were medically indicated preterm birth, whereas 5.5% were spontaneous preterm births), and 3.8% of women carried the diagnosis of chronic hypertension. Chronic hypertension was significantly associated with preterm birth in general (adjusted odds ratio, 2.74, P < .001) and medically indicated preterm birth specifically (adjusted odds ratio, 5.25, P < .001). When evaluating the effect of chronic hypertension within racial/ethnic groups, there was an increased odds of a preterm birth among hypertensive, African-American women (adjusted odds ratio, 3.91, P < .001) and hypertensive, Asian-American/Pacific Islander women (adjusted odds ratio, 3.51, P < .001) when compared with their nonhypertensive counterparts within the same racial/ethnic group. These significant effects were also noted with regard to medically indicated preterm birth for hypertensive African-American women (adjusted odds ratio, 6.85, P < .001) and Asian-American/Pacific Islander women (adjusted odds ratio, 9.87, P < .001). There was no significant association of chronic hypertension with spontaneous preterm birth (adjusted odds ratio, 0.87, P = .4). The effect of chronic hypertension on overall preterm birth and medically indicated preterm birth differs by racial/ethnic group. The larger effect of chronic hypertension among African-American and Asian/Pacific Islander women on medically indicated and total preterm birth rates raises the possibility of an independent variable that is not captured in the data analysis, although data regarding the indication for medically indicated preterm delivery was limited in this data set. Further investigation into both social-structural and biological predispositions to preterm birth should accompany research focusing on the effect of chronic hypertension on birth outcomes.

Premkumar A ，Henry DE ，Moghadassi M ，Nakagawa S ，Norton ME ... -  《-》

Racial/Ethnic Differences in Correlates of Spontaneous and Medically-Indicated Late Preterm Births among Adolescents.

To investigate the racial/ethnic differences in the correlates of spontaneous and medically-indicated late preterm birth (LPTB), defined as deliveries between 34 0/7 and 36 6/7 weeks gestation, among US adolescents. Population-based, retrospective cohort study. Births in the United States to adolescents in 2012. Adolescents (younger than 20 years; n = 171,573) who delivered nonanomalous singleton first births between 34 and 44 weeks of gestation. Bivariate and multivariable logistic regression were used to evaluate the associations between maternal risk factors and spontaneous and medically-indicated LPTB, stratified according to maternal race/ethnicity. Risk factors for spontaneous LPTB included single marital status among Asian adolescents; no insurance coverage among whites, Asian, and Hispanic adolescents; inadequate prenatal care among all racial/ethnic groups except American Indian, and adequate plus prenatal care among all races/ethnicities; prenatal smoking among whites and black adolescents; insufficient gestational weight gain among all racial/ethnic groups except American Indian; and prepregnancy underweight among white, black, and Hispanic adolescents. Risk factors for medically-indicated LPTB included inadequate prenatal care among white, black, and Hispanic adolescents, and adequate plus prenatal care among all racial/ethnic groups except Asian; insufficient gestational weight gain among white, black, and Hispanic adolescents; and prepregnancy overweight and obesity among white, black, and Hispanic adolescents. Our results show racial/ethnic differences in the correlates of spontaneous and medically-indicated LPTB among US adolescents and support the need for risk-specific interventions among different racial/ethnic groups.

Tabet M ，Jakhar S ，Williams CA ，Rawat U ，Hailegiorgis YD ，Flick LH ，Chang JJ ... -  《-》

Mediating Effects of Cardiometabolic Risk Factors on the Association Between Maternal Race-Ethnicity and Cesarean Delivery Among Low-Risk Women.

Hedderson MM ，Xu F ，Liu E ，Sridhar SB ，Quesenberry CP ，Flanagan TA ... -  《-》

Preterm Birth Risk and Maternal Nativity, Ethnicity, and Race.

Barreto A ，Formanowski B ，Peña MM ，Salazar EG ，Handley SC ，Burris HH ，Ortiz R ，Lorch SA ，Montoya-Williams D ... -  《JAMA Network Open》