Dose-response association between maternal smoking during pregnancy and the risk of infant death: a nationwide, population-based, retrospective cohort study

The use of financial incentives for smoking cessation in pregnant women: A parallel-group randomised controlled trial protocol

BACKGROUND AND AIMS

Smoking cessation during pregnancy results in short- and long-term health benefits for the mother and infant. Despite public health policies and initiatives to reduce smoking, smoking in pregnancy remains unacceptably high in Australia, particularly among populations of high disadvantage. Internationally, the use of financial incentives has shown some promise in assisting pregnant women to quit smoking, but more research is needed in different contexts. This study aims to determine the efficacy, cost-effectiveness and acceptability of the use of financial incentives in Australia.

DESIGN

2-arm parallel-group randomised controlled trial.

SETTING

Australian antenatal care setting.

PARTICIPANTS

Pregnant women who smoke.

INTERVENTION

Women randomised to the intervention group will receive financial incentives of increasing value at three time points throughout their pregnancy (4 and 12 weeks from the first antenatal visit and 37 weeks gestation) upon confirmation of smoking abstinence.

MEASUREMENTS

The primary comparison outcome is a composite binary measure of abstinence at three time points during pregnancy (4, 12 and 37 weeks). Smoking abstinence will be determined by a carbon monoxide breath analysis reading of ≤3 ppm. The primary statistical analysis is estimation of the absolute difference in the prevalence of abstinence at all three time points based on the intention-to-treat groups. A cost-effectiveness analysis will be undertaken to quantify the social returns of the intervention. A qualitative process evaluation will also be conducted to determine fidelity, contextual factors and the acceptability of the intervention to pregnant women and healthcare workers.

COMMENTS

This study will be the first Australian trial of financial incentives in reducing smoking in pregnancy. The findings will provide evidence on the acceptability, effectiveness and cost-effectiveness of financial incentives to reduce smoking in pregnancy in Australia.

Preventing Infant Mortality Through Medicaid-Administered Prenatal Care Coordination: Evidence From Wisconsin

OBJECTIVE

To estimate associations between Wisconsin Medicaid's Prenatal Care Coordination (PNCC) program and infant mortality.

DATA SOURCES AND STUDY SETTING

We analyzed birth records, Medicaid claims, and infant death records for all resident and in-state Medicaid-paid live deliveries during 2010-2018.

STUDY DESIGN

We measured PNCC exposure during pregnancy dichotomously (none; any) and categorically (none; assessment/care plan only; service receipt). Our outcome was infant mortality (death at age < 365 days). Adjusted binary logit regressions and propensity score weighted regressions tested associations between PNCC receipt and infant mortality, and we estimated probabilities and average marginal effects of infant mortality. We also executed regressions with interactions on maternal race/ethnicity to determine if associations varied across Black non-Hispanic (NH), Hispanic, and White NH births.

DATA COLLECTION/EXTRACTION METHODS

Our sample consisted of 231,540 Medicaid-paid births during 2010-2018. PNCC is only available to pregnant Medicaid beneficiaries.

PRINCIPAL FINDINGS

Infant mortality was lower among PNCC assessment/care plan only births (5.0 deaths/1000 births) and PNCC service receipt births (6.1 deaths/1000 births) relative to non-PNCC births (6.8 deaths/1000 births). This pattern was consistent in Black NH and Hispanic subgroups, but infant mortality did not vary by PNCC among White NH deliveries. Overall, adjusted binary logit regressions indicated that the probabilities of infant mortality were 0.70% for no PNCC and 0.53% for any PNCC, yielding an average marginal effect of -0.17 percentage points (95% confidence interval -0.22 percentage points, -0.11 percentage points). This association did not vary by PNCC exposure level. PNCC-infant mortality associations were significantly stronger for Black NH births relative to White NH births. Results were consistent in propensity score weighted regressions.

CONCLUSIONS

PNCC during pregnancy is associated with a lower probability of infant mortality, particularly in Black NH families. The benefit of PNCC on infant mortality may not depend on receiving services beyond care planning.

The vicious spiral in Sudden Infant Death Syndrome

Sudden Infant Death Syndrome (SIDS) is the sudden and unexpected death of an otherwise healthy infant less than 1 year of age where the cause of death remains unexplained after a thorough post-mortem investigation and evaluation of the circumstances. Epidemiological, clinical, biochemical, immunological and pathological evidence indicates that three factors must coincide for SIDS to occur: a vulnerable developmental stage of the immune system and central nervous system in the infant, predisposing factors, and external trigger events. This model is referred to as the fatal triangle or triple risk hypothesis. The concept of a vicious spiral in SIDS, starting with the fatal triangle and ending in death, is proposed as a model to understand the death mechanism. The vicious spiral is initiated by a mucosal infection and immune activation in the upper respiratory and digestive tracts, increased production of cytokines, and an overstimulation of the immature and rapidly developing immune system. A second trigger is the prone sleeping position, which may lead to rebreathing and hypercapnia, in addition to intensify the immune stimulation. In susceptible infants, this induces an aberrant cytokine production that affects sleep regulation, induces hyperthermia, and disrupts arousal mechanisms. In turn, this initiates downregulation of respiration and hypoxemia, which is worsened by nicotine. Inefficient autoresuscitation results in severe hypoxia and accumulation of hypoxic markers which, if not prevented by a normally functioning serotonergic network, contribute to a self-amplifying vicious spiral that eventually leads to coma and death. The purpose of this review is to summarize the research that underpins the concept of the vicious spiral.

Association of prenatal substance exposure and the development of the amygdala, hippocampus, and parahippocampus

CONTEXT

Prenatal substance exposure (PSE) can lead to various harmful outcomes for the developing fetus and is linked to many emotional, behavioral, and cognitive difficulties later in life. Therefore, examination of the relationship between the development of associated brain structures and PSE is important for the development of more specific or new preventative methods.

OBJECTIVES

Our study's primary objective was to examine the relationship between the physical development of the amygdala, hippocampus, and parahippocampus following prenatal alcohol, tobacco, and prescription opioid exposure.

METHODS

We conducted a cross-sectional analysis of the Adolescent Brain and Cognitive Development (ABCD) Study, a longitudinal neuroimaging study that measures brain morphometry from childhood throughout adolescence. Data were collected from approximately 12,000 children (ages 9 and 10) and parents across 22 sites within the United States. Prenatal opioid, tobacco, and alcohol use was determined through parent self-report of use during pregnancy. We extracted variables assessing the volumetric size (mm3) of the amygdala, hippocampus, and parahippocampal gyrus as well as brain volume, poverty level, age, sex, and race/ethnicity for controls within our adjusted models. We reported sociodemographic characteristics of the sample overall and by children who had PSE. We calculated and reported the means of each of the specific brain regions by substance exposure. Finally, we constructed multivariable regression models to measure the associations between different PSE and the demographic characteristics, total brain volume, and volume of each brain structure.

RESULTS

Among the total sample, 24.6% had prenatal alcohol exposure, 13.6% had prenatal tobacco exposure, and 1.2% had prenatal opioid exposure. On average, those with prenatal tobacco exposure were found to have a statistically significant smaller parahippocampus.

CONCLUSIONS

We found a significant association between prenatal tobacco exposure and smaller parahippocampal volume, which may have profound impacts on the livelihood of individuals including motor delays, poor cognitive and behavioral outcomes, and long-term health consequences. Given the cumulative neurodevelopmental effects associated with PSE, we recommend that healthcare providers increase screening rates, detection, and referrals for cessation. Additionally, we recommend that medical associations lobby policymakers to address upstream barriers to the effective identification of at-risk pregnant individuals, specifically, eliminating or significantly reducing punitive legal consequences stemming from state laws concerning prenatal substance use.

Intrapartum Electronic Cigarette Use and Birth Outcomes: Evidence from a Population-Based Study

The harms of combustible cigarette (CC) use in pregnancy for fetal development are well studied. Less understood are the potential impacts of newer non-combustible cigarette alternatives, including electronic cigarettes (ECs). Our goal was to examine whether EC use during pregnancy predicts increased risk of adverse birth outcomes. This retrospective cohort study used data from the Obstetrics Initiative (OBI), a statewide collaborative of 70 maternity hospitals. OBI's clinical registry of data on nulliparous, term, singleton, and vertex fetal presentation pregnancies were from medical records. Three groups of pregnancy cigarette users (Controls (n = 26,394), CC (n = 2216), and EC (n = 493)) were compared on birth outcomes, controlling for background differences. Controls were defined as nonsmokers of ECs or CCs. Compared to the controls, the EC group had significantly lower birth weight, while the CC group had reduced birthweight and greater rates of arterial cord pH < 7.1. Compared to EC users, CC users had higher rates of neonates requiring antibiotics and NICU admission. Growing evidence suggests ECs are not safer alternatives to CCs and use during pregnancy should be discouraged. Additional research is needed, as non-significant trends for increased risk of several adverse neonatal outcomes following EC use were found, potentially significant in larger studies with average risk for adverse pregnancy outcomes and when frequency and timing of EC exposure are considered.

Maternal cigarette smoking before or during pregnancy increases the risk of severe neonatal morbidity after delivery: a nationwide population-based retrospective cohort study

BACKGROUND

The association of maternal cigarette smoking during pregnancy with severe neonatal morbidity (SNM) is still inconclusive. We aimed to examine the associations of the timing and the intensity of maternal cigarette smoking with infant SNM in the USA.

METHODS

We used birth certificate data of 12 150 535 women aged 18-49 years who had live singleton births from the 2016-2019 US National Vital Statistics System. Women self-reported the daily number of cigarettes they consumed before pregnancy and in each trimester of pregnancy. Composite SNM was defined as one or more of the following complications: assisted ventilation immediately following delivery, assisted ventilation for >6 hours, neonatal intensive care unit admission, surfactant replacement therapy, suspected neonatal sepsis, and seizure.

RESULTS

Maternal cigarette smoking either before pregnancy or during any trimester of pregnancy significantly increased the risk of infant SNM, even at a very low intensity (ie, 1-2 cigarettes per day). For example, compared with women who did not smoke before pregnancy, the adjusted odds ratios and 95% confidence intervals (OR, 95% CI) of composite SNM in the newborn from women who smoked 1-2, 3-5, 6-9, 10-19, and ≥20 cigarettes per day before pregnancy were 1.16 (1.13 to 1.19), 1.22 (1.20 to 1.24), 1.26 (1.23 to 1.29), 1.27 (1.25 to 1.28), and 1.31 (1.30 to 1.33), respectively. Furthermore, smokers who stopped smoking during pregnancy still had a higher risk of composite SNM than never smokers before and throughout pregnancy.

CONCLUSIONS

Maternal cigarette smoking before or during pregnancy increased the risk of infant SNM, even at a low dose of 1-2 cigarettes/day. Interventions should emphasise the detrimental effects of even light smoking before and during pregnancy.

Risk of Adverse Neonatal Outcomes After Combined Prenatal Cannabis and Nicotine Exposure

Importance

The prevalence of cannabis use in pregnancy is rising and is associated with adverse perinatal outcomes. In parallel, combined prenatal use of cannabis and nicotine is also increasing, but little is known about the combined impact of both substances on pregnancy and offspring outcomes compared with each substance alone.

Objective

To assess the perinatal outcomes associated with combined cannabis and nicotine exposure compared with each substance alone during pregnancy.

Design, Setting, and Participants

This retrospective population-based cohort study included linked hospital discharge data (obtained from the California Department of Health Care Access and Information) and vital statistics (obtained from the California Department of Public Health) from January 1, 2012, through December 31, 2019. Pregnant individuals with singleton gestations and gestational ages of 23 to 42 weeks were included. Data were analyzed from October 14, 2023, to March 4, 2024.

Exposures

Cannabis-related diagnosis and prenatal nicotine product use were captured using codes from International Classification of Diseases, Ninth Revision, Clinical Modification, and International Statistical Classification of Diseases, Tenth Revision, Clinical Modification.

Main Outcome and Measures

The main outcomes were infant and neonatal death, infants small for gestational age, and preterm delivery. Results were analyzed by multivariable Poisson regression models.

Results

A total of 3 129 259 pregnant individuals were included (mean [SD] maternal age 29.3 [6.0] years), of whom 23 007 (0.7%) had a cannabis-related diagnosis, 56 811 (1.8%) had a nicotine-use diagnosis, and 10 312 (0.3%) had both in pregnancy. Compared with nonusers, those with cannabis or nicotine use diagnoses alone had increased rates of infant (0.7% for both) and neonatal (0.3% for both) death, small for gestational age (14.3% and 13.7%, respectively), and preterm delivery (<37 weeks) (12.2% and 12.0%, respectively). Moreover, risks in those with both cannabis and nicotine use were higher for infant death (1.2%; adjusted risk ratio [ARR], 2.18 [95% CI, 1.82-2.62]), neonatal death (0.6%; ARR, 1.76 [95% CI, 1.36-2.28]), small for gestational age (18.0%; ARR, 1.94 [95% CI, 1.86-2.02]), and preterm delivery (17.5%; ARR, 1.83 [95% CI, 1.75-1.91]).

Conclusions and Relevance

These findings suggest that co-occurring maternal use of cannabis and nicotine products in pregnancy is associated with an increased risk of infant and neonatal death and maternal and neonatal morbidity compared with use of either substance alone. Given the increasing prevalence of combined cannabis and nicotine use in pregnancy, these findings can help guide health care practitioners with preconception and prenatal counseling, especially regarding the benefits of cessation.

Maternal opioid use disorder and infant mortality in Wisconsin, United States, 2010-2018

OBJECTIVE

The difference in infant health outcomes by maternal opioid use disorder (OUD) status is understudied. We measured the association between maternal OUD during pregnancy and infant mortality and investigated whether this association differs by infant neonatal opioid withdrawal syndrome (NOWS) or maternal receipt of medication for OUD (MOUD) during pregnancy.

METHODS

We sampled 204,543 Medicaid-paid births from Wisconsin, United States (2010-2018). The primary exposure was any maternal OUD during pregnancy. We also stratified this exposure on NOWS diagnosis (no OUD; OUD without NOWS; OUD with NOWS) and on maternal MOUD receipt (no OUD; OUD without MOUD; OUD with <90 consecutive days of MOUD; OUD with 90+ consecutive days of MOUD). Our outcome was infant mortality (death at age <365 days). Demographic-adjusted logistic regressions measured associations with odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Maternal OUD was associated with increased odds of infant mortality (OR 1.43; 95% CI 1.02-2.02). After excluding infants who died <5 days post-birth (i.e., before the clinical presentation of NOWS), regression estimates of infant mortality did not significantly differ by NOWS diagnosis. Likewise, regression estimates did not significantly differ by maternal MOUD receipt in the full sample.

CONCLUSIONS

Maternal OUD is associated with an elevated risk of infant mortality without evidence of modification by NOWS nor by maternal MOUD treatment. Future research should investigate potential mechanisms linking maternal OUD, NOWS, MOUD treatment, and infant mortality to better inform clinical intervention.