Deprived neighborhoods and spontaneous preterm birth: A national cohort study

Examining modification of the associations between air pollution and birth outcomes by neighborhood deprivation in a North Carolina birth cohort, 2011-2015

Background

Evidence from studies of air pollutants and birth outcomes suggests an association, but uncertainties around geographical variability and modifying factors still remain. As neighborhood-level social characteristics are associated with birth outcomes, we assess whether neighborhood deprivation level is an effect measure modifier on the association between air pollution and birth outcomes in a North Carolina birth cohort.

Methods

Using birth certificate data, all North Carolina residential singleton live births from 1 January 2011 to 31 December 2015 with gestational ages of 20-44 weeks (n = 566,799) were examined for birth defect diagnoses and preterm birth. Exposures were daily average fine particulate matter (PM2.5), daily 8-h maximum nitrogen dioxide (NO2), and daily 8-h maximum ozone (O3) modeled concentrations, and the modifier of interest was the neighborhood deprivation index (NDI). Linear binomial models were used to estimate the prevalence differences and 95% confidence intervals (CI) for the association between ambient air pollution and birth defect diagnoses. Modified Poisson regression models were used to estimate risk differences (RDs) and 95% CIs for air pollution and preterm birth. Models were stratified by the neighborhood deprivation index group (low, medium, or high) to assess potential modification by NDI.

Results

Approximately 3.1% of the study population had at least one birth defect and 8.18% were born preterm. For preterm birth, associations with PM2.5 and O3 did not follow a conclusive pattern and there was no evidence of modification by NDI. The associations between NO2 and preterm birth were generally negative across exposure windows except for a positive association with NO2 and preterm birth for high NDI [RD: 34.70 (95% CI 4.84-64.56)] for entire pregnancy exposure. There was no evidence of associations between pollutants examined and birth defects.

Conclusions

There may be differences in the association between NO2 exposure and preterm birth by NDI but we did not observe any evidence of associations for birth defects. Our results support the public health protection afforded by reductions in air pollution, even in areas of neighborhood deprivation, but future research conducted in areas with higher levels of air pollution and evaluating the potential for modification by neighborhood deprivation level would be informative.

Deprived areas and adverse perinatal outcome: a systematic review

PURPOSE

This systematic review aimed to assess if women living in deprived areas have worse perinatal outcomes than those residing in high-income areas.

METHODS

Datasets of PubMed, ScienceDirect, CENTRAL, Embase, and Google Scholar were searched for studies comparing perinatal outcomes (preterm birth, small-for-gestational age, and stillbirth) in deprived and non-deprive areas.

RESULTS

A total of 46 studies were included. The systematic review of the literature revealed a higher risk for adverse perinatal outcomes such as preterm birth, small for gestational age, and stillbirth in deprived areas.

CONCLUSION

Deprived areas are associated with adverse perinatal outcomes. More multifactorial studies are needed to assess the weight of each factor that composes the socioeconomic gradient of health in adverse perinatal outcomes.

Do women living in a deprived neighborhood have higher maternity care costs and worse pregnancy outcomes? A retrospective population-based study

BACKGROUND

Living in a deprived neighborhood is associated with poorer health, due to factors such as lower socio-economic status and an adverse lifestyle. There is little insight into whether living in deprived neighborhood is associated with adverse maternity care outcomes and maternity health care costs. We expect women in a deprived neighborhood to experience a more complicated pregnancy, with more secondary obstetric care (as opposed to primary midwifery care) and higher maternity care costs. This study aimed to answer the following research question: to what extent are moment of referral from primary to secondary care, mode of delivery, (extreme or very) preterm delivery and maternity care costs associated with neighborhood deprivation?

METHODS

This retrospective cohort study used a national Dutch database with healthcare claims processed by health insurers. All pregnancies that started in 2018 were included. The moment of referral from primary to secondary care, mode of delivery, (extreme or very) preterm delivery and maternity care costs were compared between women in deprived and non-deprived neighborhoods. We reported descriptive statistics, and results of ordinal logistic, multinomial and linear regressions to assess whether differences between the two groups exist.

RESULTS

Women in deprived neighborhoods had higher odds of being referred from primary to secondary care during pregnancy (adjusted OR 1.49, 95%CI 1.41-1.57) and to start their pregnancy in secondary care (adjusted OR 1.55, 95%CI 1.44-1.66). Furthermore, women in deprived neighborhoods had lower odds of assisted delivery than women in non-deprived neighborhoods (adjusted OR 0.73, 95%CI 0.66-0.80), and they had higher odds of a cesarean section (adjusted OR 1.19, 95%CI 1.13-1.25). On average, women in a deprived neighborhood had higher maternity care costs worth 156 euros (95%CI 104-208).

CONCLUSION

This study showed that living in a deprived neighborhood is associated with more intensive maternal care and higher maternal care costs in the Netherlands. These findings support the needs for greater attention to socio-economic factors in maternity care in the Netherlands.

Cervical pessary versus vaginal progesterone in women with a singleton pregnancy, a short cervix, and no history of spontaneous preterm birth at less than 34 weeks' gestation: open label, multicentre, randomised, controlled trial

OBJECTIVE

To compare the effectiveness of cervical pessary and vaginal progesterone in the prevention of adverse perinatal outcomes and preterm birth in pregnant women of singletons with no prior spontaneous preterm birth at less than 34 weeks' gestation and who have a short cervix of 35 mm or less.

DESIGN

Open label, multicentre, randomised, controlled trial.

SETTING

20 hospitals and five obstetric ultrasound practices in the Netherlands.

PARTICIPANTS

Women with a healthy singleton pregnancy and an asymptomatic short cervix of 35 mm or less between 18 and 22 weeks' gestation were eligible. Exclusion criteria were prior spontaneous preterm birth at less than 34 weeks, a cerclage in situ, maternal age of younger than 18 years, major congenital abnormalities, prior participation in this trial, vaginal blood loss, contractions, cervical length of less than 2 mm or cervical dilatation of 3 cm or more. Sample size was set at 628 participants.

INTERVENTIONS

1:1 randomisation to an Arabin cervical pessary or vaginal progesterone 200 mg daily up to 36 weeks' of gestation or earlier in case of ruptured membranes, signs of infection, or preterm labour besides routine obstetric care.

MAIN OUTCOME MEASURES

Primary outcome was a composite adverse perinatal outcome. Secondary outcomes were rates of (spontaneous) preterm birth at less than 28, 32, 34, and 37 weeks. A predefined subgroup analysis was planned for cervical length of 25 mm or less.

RESULTS

From 1 July 2014 to 31 March 2022, 635 participants were randomly assigned to pessary (n=315) or to progesterone (n=320). 612 were included in the intention to treat analysis. The composite adverse perinatal outcome occurred in 19 (6%) of 303 participants with a pessary versus 17 (6%) of 309 in the progesterone group (crude relative risk 1.1 (95% confidence interval (CI) 0.60 to 2.2)). The rates of spontaneous preterm birth were not significantly different between groups. In the subgroup of cervical length of 25 mm or less, spontaneous preterm birth at less than 28 weeks occurred more often after pessary than after progesterone (10/62 (16%) v 3/69 (4%), relative risk 3.7 (95% CI 1.1 to 12.9)) and adverse perinatal outcomes seemed more frequent in the pessary group (15/62 (24%) v 8/69 (12%), relative risk 2.1 (0.95 to 4.6)).

CONCLUSIONS

In women with a singleton pregnancy with no prior spontaneous preterm birth at less than 34 weeks' gestation and with a midtrimester short cervix of 35 mm or less, pessary is not better than vaginal progesterone. In the subgroup of a cervical length of 25 mm or less, a pessary seemed less effective in preventing adverse outcomes. Overall, for women with single baby pregnancies, a short cervix, and no prior spontaneous preterm birth less than 34 weeks' gestation, superiority of a cervical pessary compared with vaginal progesterone to prevent preterm birth and consecutive adverse outcomes could not be proven.

TRIAL REGISTRATION

International Clinical Trial Registry Platform (ICTRP, EUCTR2013-002884-24-NL).

Impact of ethnicity and neighborhood deprivation on preterm birth: How does urban living play a role?

OBJECTIVE

Women of Black and other non-Western ethnicity and women who live in deprived neighborhoods are at increased risk for preterm birth (PTB). These women may live clustered in certain urban areas. If ethnicity reflects a biological rather than a socioeconomic risk factor, women should have a PTB risk independent of the urban area where they live. In this study we explored the association between urban living and the risk of PTB, combined with knowledge on ethnicity and neighborhood deprivation in these specific urban areas in the Netherlands.

STUDY DESIGN

National cohort study of 935,381 women (2014-2019) with a singleton pregnancy resulting in live birth between 24.0 and 42.6 weeks. Antepartum death and severe congenital anomalies were excluded. We performed logistic regression analysis and analyzed the impact of living in one of the four main urban areas on PTB. We adjusted for maternal age, parity and fetal gender. We tested for interaction between ethnicity, neighborhood deprivation index (NDI) and urban living.

RESULTS

Mean PTB rate among singleton pregnancies in The Netherlands is 5.1%. There was a strong ethnic difference in PTB risk, with the highest prevalence among South Asian women (7.9%) and African women (6.6%). In the most deprived neighborhoods the PTB risk was 5.7%. We found a significant interaction between ethnicity and urban living, and between NDI and urban living. South Asian and African women living in urban areas had the greatest risk of PTB, between 7.0% and 8.8%.

CONCLUSION

Ethnicity remains a fixed biological risk for PTB that cannot be fully explained by socioeconomic status or neighborhood deprivation. Independent of ethnicity and neighborhood deprivation, urban living has a great influence on the risk of preterm birth. Future studies and policies should focus on population-based interventions in those urban areas where South Asian and African ethnic groups live and where the preterm birth risk is the highest.