Comparison of gestational dating methods and implications for exposure-outcome associations: an example with PM2.5 and preterm birth

The effect of antenatal isoniazid preventive therapy on birth outcomes in Western Kenya

BACKGROUND: Pregnant women living with HIV (WLHIV) are at high risk for TB. There are limited data to inform whether TB preventive therapy is safe in pregnancy.METHODS: We completed a retrospective study of antenatal and birth records of mother-infant dyads at two health care facilities in Kisumu, Kenya. Among pregnant WLHIV, we assessed the relationship of antenatal isoniazid preventive therapy (IPT) with birth outcomes (preterm birth, low birth weight [LBW], congenital anomalies, and perinatal death).RESULTS: Of 576 mother-infant pairs, most women were on antiretroviral therapy (574, 99.7%) with viral suppression (518, 89.9%) and one-quarter had IPT exposure during pregnancy (152, 26.4%). The prevalence of preterm birth was lower among women with antenatal IPT exposure (21% vs. 30%; P = 0.03). LBW, congenital anomaly and perinatal death were not associated with antenatal IPT; however, we observed a trend toward fewer composite poor birth outcomes among women taking antenatal IPT (26% vs 33%; P = 0.08). Controlling for maternal age and viral load, IPT use during pregnancy was associated with lower odds of preterm birth (aOR 0.62, 95% CI 0.40-0.98; P = 0.04).CONCLUSION: In a programmatic setting in Western Kenya, IPT use was not associated with adverse birth outcomes.

Sulfur dioxide reduction at coal-fired power plants in North Carolina and associations with preterm birth among surrounding residents

Coal-fired power plants (CFPP) are major contributors of air pollution, including the majority of anthropogenic sulfur dioxide (SO2) emissions, which have been associated with preterm birth (PTB). To address a 2002 North Carolina (NC) policy, 14 of the largest NC CFPPs either installed desulfurization equipment (scrubbers) or retired coal units, resulting in substantial reductions of SO2 air emissions. We investigated whether SO2 air emission reduction strategies at CFPPs in NC were associated with changes in prevalence of PTB in nearby communities.

Methods

We used US EPA Air Markets Program Data to track SO2 emissions and determine the implementation dates of intervention at CFPPs and geocoded 2003-2015 NC singleton live births. We conducted a difference-in-difference analysis to estimate change in PTB associated with change in SO2 reduction strategies for populations living 0-<4 and 4-<10 miles from CFPPs pre- and postintervention, with a comparison of those living 10-<15 miles from CFPPs.

Results

With the spatial-temporal exposure restrictions applied, 42,231 and 41,218 births were within 15 miles of CFPP-scrubbers and CFPP-retired groups, respectively. For residents within 4-<10 miles from a CFPP, we estimated that the absolute prevalence of PTB decreased by -1.5% [95% confidence interval (CI): -2.6, -0.4] associated with scrubber installation and -0.5% (95% CI: -1.6, 0.6) associated with the retirement of coal units at CFPPs. Our findings were imprecise and generally null-to-positive among those living within 0-<4 miles regardless of the intervention type.

Conclusions

Results suggest a reduction of PTB among residents 4-<10 miles of the CFPPs that installed scrubbers.

Behavioral Interventions can Mitigate Adverse Pregnancy Outcomes Among Women Conceiving on ART and Those Initiated on ART During Pregnancy: Findings From the MOTIVATE Trial in Southwestern Kenya

BACKGROUND

Antiretroviral therapy (ART) is essential for the elimination of mother-to-child transmission and improved health outcomes for women living with HIV (WLWH). However, adverse pregnancy outcomes (APOs) among pregnant women on ART are a growing concern.

METHODS

We investigated the associations between timing of ART initiation and APOs among pregnant WLWH receiving behavioral interventions (community mentor mothers and text messaging) in the Mother-Infant Visit Adherence and Treatment Engagement (MOTIVATE) study in southwestern Kenya. Log binomial models were used for estimation of relative risks (RRs) (adjusted for the clustered nature of data) evaluating APOs with 3 exposure comparisons: (1) preconception ART initiation vs. postconception initiation; (2) among postconception ART initiating women, comparisons across gestational ages at cART initiation (first versus second and third trimester exposure), and (3) intervention allocation.

RESULTS

Of the 1275 women included in this analysis, 388 (30%) had an APO: 306 preterm births, 38 low birth weight infants, 33 stillbirths, and 11 miscarriages. In multivariable analysis, viral load ≥1000 copies/mL, moderate and severe anemia at baseline increased risk of APOs. Among women initiating ART before and after conception, no difference was observed in the composite APO. Women who received community mentor mother visits alone (aRR 0.74: 95% CI: 0.71 to 0.76) or text messages alone (aRR 0.79: 95% CI: 0.70 to 0.89) had lower risks of experiencing any APOs.

CONCLUSIONS

Receiving supportive behavioral interventions may mitigate the risk of experiencing an APO among WLWH on ART. Further studies are needed to investigate the underlying mechanisms and optimize the benefits of these interventions.

Normotensive preterm delivery and maternal cardiovascular risk factor trajectories across the life course: The HUNT Study, Norway

INTRODUCTION

Preterm delivery (<37 weeks) predicts later cardiovascular disease risk in mothers, even among normotensive deliveries. However, development of subclinical cardiovascular risk before and after preterm delivery is not well understood. We sought to investigate differences in life course cardiovascular risk factor trajectories based on preterm delivery history.

MATERIAL AND METHODS

The HUNT Study (1984-2008) linked with the Medical Birth Registry of Norway (1967-2012) yielded clinical measurements and pregnancy outcomes for 19 806 parous women with normotensive first deliveries. Women had up to three measurements of body mass index, waist-to-hip ratio, blood pressure, lipids, non-fasting glucose, and C-reactive protein during follow up between 21 years before to 41 years after first delivery. Using mixed effects models, we compared risk factor trajectories for women with preterm vs term/postterm first deliveries.

RESULTS

Trajectories overlapped for women with preterm compared with term/postterm first deliveries for all cardiovascular risk factors examined. For instance, the mean difference in systolic blood pressure in women with preterm first deliveries compared with those with term deliveries was 0.2 mm Hg (95% CI -1.8 to 2.3) at age 20 and 1.5 mm Hg (95% CI -0.5 to 3.6) at age 60.

CONCLUSIONS

A history of preterm delivery was not associated with different life course trajectories of common cardiovascular risk factors in our study population. This suggests that the robust association between preterm delivery and cardiovascular end points in Norway or similar contexts is not explained by one or more commonly measured cardiovascular risk factors. Overall, we did not find evidence for a single cardiovascular disease prevention strategy that would reduce risk among the majority of women who had preterm delivery.

Prenatal airshed pollutants and preterm birth in an observational birth cohort study in Detroit, Michigan, USA

Detroit, Michigan, currently has the highest preterm birth (PTB) rate of large cities in the United States. Disproportionate exposure to ambient air pollutants, including particulate matter ≤2.5 μm (PM_2.5), PM ≤ 10 μm (PM₁₀), nitrogen dioxide (NO₂) and benzene, toluene, ethylbenzene, and xylenes (BTEX) may contribute to PTB. Our objective was to examine the association of airshed pollutants with PTB in Detroit, MI. The Geospatial Determinants of Health Outcomes Consortium (GeoDHOC) study collected air pollution measurements at 68 sites in Detroit in September 2008 and June 2009. GeoDHOC data were coupled with 2008-2010 Michigan Air Sampling Network measurements in Detroit to develop monthly ambient air pollution estimates at a spatial density of 300 m². Using delivery records from two urban hospitals, we established a retrospective birth cohort of births by Detroit women occurring from June 2008 to May 2010. Estimates of air pollutant exposure throughout pregnancy were assigned to maternal address at delivery. Our analytic sample size included 7961 births; 891 (11.2%) were PTB. After covariate adjustment, PM₁₀ (P = 0.003) and BTEX (P < 0.001), but not PM_2.5 (P = 0.376) or NO₂ (P = 0.582), were statistically significantly associated with PTB. In adjusted models, for every 5-unit increase in PM₁₀ there was a 1.21 times higher odds of PTB (95% CI 1.07, 1.38) and for every 5-unit increase in BTEX there was a 1.54 times higher odds of PTB (95% CI 1.25, 1.89). Consistent with previous studies, higher PM₁₀ was associated with PTB. We also found novel evidence that higher airshed BTEX is associated with PTB. Future studies confirming these associations and examining direct measures of exposure are needed.

Impacts of gestational age uncertainty in estimating associations between preterm birth and ambient air pollution

Supplemental Digital Content is available in the text.

Background:

Previous epidemiologic studies utilizing birth records have shown heterogeneous associations between air pollution exposure during pregnancy and the risk of preterm birth (PTB, gestational age <37 weeks). Uncertainty in gestational age at birth may contribute to this heterogeneity.

Methods:

We first examined disagreement between clinical and last menstrual period-based (LMP) determination of PTB from individual-level birth certificate data for the 20-county Atlanta metropolitan area during 2002 to 2006. We then estimated associations between five trimester-averaged pollutant exposures and PTB, defined using various methods based on the clinical or LMP gestational age. Finally, using a multiple imputation approach, we incorporated uncertainty in gestational age to quantify the impact of this variability on associations between pollutant exposures and PTB.

Results:

Odds ratios (OR) were most elevated when a more stringent definition of PTB was used. For example, defining PTB only when LMP and clinical diagnoses agree yielded an OR of 1.09 (95% confidence interval [CI] = 1.04, 1.14) per interquartile range increase in first trimester carbon monoxide exposure versus an OR of 1.04 (95% CI = 1.01, 1.08) when PTB was defined as either an LMP or clinical diagnosis. Accounting for outcome uncertainty resulted in wider CIs—between 7.4% and 43.8% wider than those assuming the PTB outcome is without error.

Conclusions:

Despite discrepancies in PTB derived using either the clinical or LMP gestational age estimates, our analyses demonstrated robust positive associations between PTB and ambient air pollution exposures even when gestational age uncertainty is present.

Impact of eating disorders on obstetric outcomes in a large clinical sample: A comparison with the HUNT study

OBJECTIVE

Current evidence from clinical studies suggests that having an active eating disorder (ED) during pregnancy is associated with unfavorable obstetric outcomes. However, the role of a lifetime diagnosis of ED is not fully understood. Variations in findings suggest a need for additional studies of maternal ED. This study aims to identify associations between a lifetime ED and obstetric outcomes.

METHOD

Data from a hospital patient register and a population-based study (The HUNT Study) were linked to the Medical Birth Registry in Norway. Register based information of obstetric complications (preeclampsia, preterm birth, perinatal deaths, small for gestational age (SGA), large for gestational age (LGA), Caesarean sections, and 5-min Apgar score) were acquired for 532 births of women with ED and 43,657 births of non-ED women. Multivariable regression in generalized estimating equations was used to account for clusters within women as they contributed multiple births to the dataset.

RESULTS

After adjusting for parity, maternal age, marital status, and year of delivery, lifetime history of anorexia nervosa was associated with increased odds of having offspring who were SGA (Odds ratio (OR) 2.7, 95% Confidence Interval (CI) 1.4-5.2). Women with a lifetime history of bulimia nervosa had higher odds of having a Caesarian section (OR 1.7 95% CI 1.1-2.5). Women with EDNOS/sub-threshold ED had a higher likelihood of having a low Apgar score at 5 min (OR 3.1, 95% CI 1.1-8.8).

CONCLUSION

Our study corroborates available evidence on the associations between maternal ED and adverse obstetric outcomes.