Mid-gestation serum lipidomic profile associations with spontaneous preterm birth are influenced by body mass index

Spontaneous preterm birth (sPTB) is a major cause of infant morbidity and mortality. While metabolic changes leading to preterm birth are unknown, several factors including dyslipidemia and inflammation have been implicated and paradoxically both low (<18.5 kg/m²) and high (>30 kg/m²) body mass indices (BMIs) are risk factors for this condition. The objective of the study was to identify BMI-associated metabolic perturbations and potential mid-gestation serum biomarkers of preterm birth in a cohort of underweight, normal weight and obese women experiencing either sPTB or full-term deliveries (n = 102; n = 17/group). For this purpose, we combined untargeted metabolomics and lipidomics with targeted metabolic profiling of major regulators of inflammation and metabolism, including oxylipins, endocannabinoids, bile acids and ceramides. Women who were obese and had sPTB showed elevated oxidative stress and dyslipidemia characterized by elevated serum free fatty acids. Women who were underweight-associated sPTB also showed evidence of dyslipidemia characterized by elevated phospholipids, unsaturated triglycerides, sphingomyelins, cholesteryl esters and long-chain acylcarnitines. In normal weight women experiencing sPTB, the relative abundance of 14(15)-epoxyeicosatrienoic acid and 14,15-dihydroxyeicosatrienoic acids to other regioisomers were altered at mid-pregnancy. This phenomenon is not yet associated with any biological process, but may be linked to estrogen metabolism. These changes were differentially modulated across BMI groups. In conclusion, using metabolomics we observed distinct BMI-dependent metabolic manifestations among women who had sPTB. These observations suggest the potential to predict sPTB mid-gestation using a new set of metabolomic markers and BMI stratification. This study opens the door to further investigate the role of cytochrome P450/epoxide hydrolase metabolism in sPTB.

Quantification of selection bias in studies of risk factors for birth defects among livebirths

BACKGROUND

Risk factors for birth defects are frequently investigated using data limited to liveborn infants. By conditioning on survival, results of such studies may be distorted by selection bias, also described as "livebirth bias." However, the implications of livebirth bias on risk estimation remain poorly understood.

OBJECTIVES

We sought to quantify livebirth bias and to investigate the conditions under which it arose.

METHODS

We used data on 3994 birth defects cases and 11 829 controls enrolled in the National Birth Defects Prevention Study to compare odds ratio (OR) estimates of the relationship between three established risk factors (antiepileptic drug use, smoking, and multifetal pregnancy) and four birth defects (anencephaly, spina bifida, omphalocele, and cleft palate) when restricted to livebirths as compared to among livebirths, stillbirths, and elective terminations. Exposures and birth defects represented varying strengths of association with livebirth; all controls were liveborn. We performed a quantitative bias analysis to evaluate the sensitivity of our results to excluding terminated and stillborn controls.

RESULTS

Cases ranged from 33% liveborn (anencephaly) to 99% (cleft palate). Smoking and multifetal pregnancy were associated with livebirth among anencephaly (crude OR [cOR] 0.61 and cOR 3.15, respectively) and omphalocele cases (cOR 2.22 and cOR 5.22, respectively). For analyses of the association between exposures and birth defects, restricting to livebirths produced negligible differences in estimates except for anencephaly and multifetal pregnancy, which was twofold higher among livebirths (adjusted OR [aOR] 4.93) as among all pregnancy outcomes (aOR 2.44). Within tested scenarios, bias analyses suggested that results were not sensitive to the restriction to liveborn controls.

CONCLUSIONS

Selection bias was generally limited except for high mortality defects in the context of exposures strongly associated with livebirth. Findings indicate that substantial livebirth bias is unlikely to affect studies of risk factors for most birth defects.

Maternal dietary fat intake and the risk of congenital heart defects in offspring

BACKGROUND

Fatty acids are crucial in embryologic development, including cardiogenesis. The impact of maternal periconceptional dietary fat intake on the risk of congenital heart defects (CHDs) has not been clearly elucidated. We hypothesized that maternal dietary fat intake during pregnancy is associated with risk of CHDs in offspring.

METHODS

We analyzed CHD cases and nonmalformed controls from the National Birth Defects Prevention Study, a case-control, multicenter population-based study of birth defects. We used multivariable logistic regression to analyze the association between maternal periconceptional dietary fat intake and occurrence of CHDs.

RESULTS

We examined 11,393 infants with CHDs (cases) and 11,029 infants without birth defects (controls). Multivariable analysis of maternal dietary fat intake adjusted for maternal energy intake demonstrated modest change in risk for 2 of the 25 CHDs analyzed; otherwise there was no association. Maternal dietary fat intake unadjusted for total energy was associated with increased risk for several CHDs.

CONCLUSIONS

After adjusting for total energy intake, maternal periconceptional dietary fat intake has a modest association with risk of a few specific CHDs. If maternal dietary fat intake does impact CHD risk, the effect is minimal.

IMPACT

In this large, case-control study, after adjusting for total caloric intake, maternal periconceptional dietary fat intake was not associated with increased odds of congenital heart defects. This study investigates the hypothesis that women's periconceptional fat intake alters the risk of congenital heart defects in offspring. Our results raise questions about the role maternal fat intake may play in cardiogenesis and risk of congenital heart defects. Additionally, they raise the question about whether maternal lipid metabolism, as opposed to fat intake, may influence cardiac development.

Defining critical factors in multi-country studies of assisted reproductive technologies (ART): data from the US and UK health systems

As the worldwide use of assisted reproductive technologies (ART) continues to grow, there is a critical need to assess the safety of these treatment parameters and the potential adverse health effects of their use in adults and their offspring. While key elements remain similar across nations, geographic variations both in treatments and populations make generalizability challenging. We describe and compare the demographic factors between the USA and the UK related to ART use and discuss implications for research. The USA and the UK share some common elements of ART practice and in how data are collected regarding long-term outcomes. However, the monitoring of ART in these two countries each brings strengths that complement each other's limitations.

Residential proximity to green space and preeclampsia in California

Background

We investigated whether residing near more green space might reduce the risk of preeclampsia.

Methods

Participants were women who delivered a live, singleton birth between 1998 and 2011 in eight counties of the San Joaquin Valley in California. There were 7276 cases of preeclampsia divided into mild, severe, or superimposed on preexisting hypertension. Controls were 197,345 women who did not have a hypertensive disorder and delivered between 37 and 41 weeks. Green space was estimated from satellite data using Normalized Difference Vegetation Index (NDVI), an index calculated from surface reflectance at the visible and near-infrared wavelengths. Values closer to 1 denote a higher density of green vegetation. Average NDVI was calculated within a 50 m, 100 m, and 500 m buffer around each woman's residence. Odds ratios and 95% confidence intervals were estimated comparing the lowest and highest quartiles of mean NDVI to the interquartile range comparing each preeclampsia phenotype, divided into early (20-31 weeks) and late (32-36 weeks) preterm birth, to full-term controls.

Results

We observed an inverse association in the 500 m buffer for women in the top quartile of NDVI and a positive association for women in the lowest quartile of NDVI for women with superimposed preeclampsia. There were no associations in the 50 and 100 m buffers.

Conclusion

Within a 500 m buffer, more green space was inversely associated with superimposed preeclampsia. Future work should explore the mechanism by which green space may protect against preeclampsia.

Factors Associated with Timeliness of Surgical Repair among Infants with Myelomeningocele: California Perinatal Quality Care Collaborative, 2006 to 2011

OBJECTIVE

This study aimed to examine factors associated with timely (0-2 days after birth) myelomeningocele surgical repair.

STUDY DESIGN

We examined 2006 to 2011 births from the California Perinatal Quality Care Collaborative, linking to hospital discharge and vital records. Selected maternal, infant, and delivery hospital characteristics were evaluated to understand disparities in timely repair. Poisson regression was used to estimate adjusted risk ratios (aRRs) and 95% confidence intervals (CIs).

RESULTS

Overall, 399 of the 450 (89%) infants had a timely repair and approximately 80% of them were delivered in level III/IV hospitals. Infants with hydrocephalus were significantly less likely to have a delayed myelomeningocele repair compared with those without (aRR = 0.22; 95% CI = 0.13, 0.39); infants whose medical care was paid by Medi-Cal or other nonprivate insurance were 2.2 times more likely to have a delayed repair compared with those covered by a private insurance (aRR = 2.23; 95% CI = 1.17, 4.27). Low birth weight was a significant predictor for delayed repair (aRR = 2.06; 95% CI = 1.10, 3.83).

CONCLUSION

There was a significant disparity in myelomenigocele repair based on medical care payer. Families and hospitals should work together for timely repair in hospitals having specialized multidisciplinary teams. Findings from the study can be used to follow best clinical practices for myelomeningocele repair.

Evaluation of US State-Level Variation in Hypertensive Disorders of Pregnancy

IMPORTANCE

Hypertensive disorders of pregnancy are important causes of maternal and perinatal morbidity in the US. However, the extent of statewide variation in the prevalence of chronic hypertension, pregnancy-induced hypertension or preeclampsia, and eclampsia in the US remains unknown.

OBJECTIVE

To examine the extent of statewide variation in the prevalence of chronic hypertension, hypertensive disorders of pregnancy (including pregnancy-induced hypertension or preeclampsia), and eclampsia in the US.

DESIGN, SETTING, AND PARTICIPANTS

A cross-sectional study using 2017 US birth certificate data was conducted from September 1, 2019, to February 1, 2020. A population-based sample of 3 659 553 women with a live birth delivery was included.

MAIN OUTCOMES AND MEASURES

State-specific prevalence of chronic hypertension, hypertensive disorders of pregnancy, and eclampsia was assessed using multilevel multivariable logistic regression, with the median odds ratio (MOR) to evaluate statewide variation.

RESULTS

Of the 3 659 553 women, 185 932 women (5.1%) were younger than 20 years, 727 573 women (19.9%) were aged between 20 and 24 years, 1 069 647 women (29.2%) were aged between 25 and 29 years, 1 037 307 women (28.3%) were aged between 30 and 34 years, 523 607 women (14.3%) were aged between 35 and 39 years, and 115 487 women (3.2%) were 40 years or older. Most women had Medicaid (42.8%) or private insurance (49.4%). Hawaii had the lowest adjusted prevalence of chronic hypertension (1.0%; 95% CI, 0.9%-1.2%), and Alaska had the highest (3.4%; 95% CI, 3.0%-3.9%). Massachusetts had the lowest adjusted prevalence of hypertensive disorders of pregnancy (4.3%; 95% CI, 4.1%-4.6%), and Louisiana had the highest (9.3%; 95% CI, 8.9%-9.8%). Delaware had the lowest adjusted prevalence of eclampsia (0.03%; 95% CI, 0.01%-0.09%), and Hawaii had the highest (2.8%; 95% CI, 2.2%-3.4%). The degree of statewide variation was high for eclampsia (MOR, 2.36; 95% CI, 1.88-2.82), indicating that the median odds of eclampsia were 2.4-fold higher if the same woman delivered in a US state with a higher vs lower prevalence of eclampsia. Modest variation between states was observed for chronic hypertension (MOR, 1.27; 95% CI, 1.20-1.33) and hypertensive disorders of pregnancy (MOR, 1.17; 95% CI, 1.13-1.21).

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that after accounting for patient-level and state-level variables, substantial state-level variation exists in the prevalence of eclampsia. These data can inform future public-health inquiries to identify reasons for the eclampsia variability.

Integration of mechanistic immunological knowledge into a machine learning pipeline improves predictions

The dense network of interconnected cellular signalling responses that are quantifiable in peripheral immune cells provides a wealth of actionable immunological insights. Although high-throughput single-cell profiling techniques, including polychromatic flow and mass cytometry, have matured to a point that enables detailed immune profiling of patients in numerous clinical settings, the limited cohort size and high dimensionality of data increase the possibility of false-positive discoveries and model overfitting. We introduce a generalizable machine learning platform, the immunological Elastic-Net (iEN), which incorporates immunological knowledge directly into the predictive models. Importantly, the algorithm maintains the exploratory nature of the high-dimensional dataset, allowing for the inclusion of immune features with strong predictive capabilities even if not consistent with prior knowledge. In three independent studies our method demonstrates improved predictions for clinically relevant outcomes from mass cytometry data generated from whole blood, as well as a large simulated dataset. The iEN is available under an open-source licence.

Reproductive sequelae of parental severe illness before the pandemic: implications for the COVID-19 pandemic

OBJECTIVE

To investigate, with pre-COVID-19 data, whether parental exposure to severe systemic infections near the time of conception is associated with pregnancy outcomes.

DESIGN

Retrospective cohort study.

SETTING

Population-based study covering births within the United States from 2009 to 2016.

PARTICIPANTS

The IBM MarketScan Research database covers reimbursed health care claims data on inpatient and outpatient encounters that are privately insured through employment-sponsored health insurance. Our analytic sample included pregnancies to paired fathers and mothers.

INTERVENTIONS(S)

Parental preconception exposure (0-6 months before conception) to severe systemic infection (e.g., sepsis, hypotension, respiratory failure, critical care evaluation).

MAIN OUTCOME MEASURE(S)

Preterm birth (i.e., live birth before 37 weeks) and pregnancy loss.

RESULT(S)

A total of 999,866 pregnancies were recorded with 214,057 pregnancy losses (21.4%) and 51,759 preterm births (5.2%). Mothers receiving intensive care in the preconception period had increased risk of pregnancy loss, as did fathers. Mothers with preconception sepsis had higher risk of preterm birth and pregnancy loss, and paternal sepsis exposure was associated with an increased risk of pregnancy loss. Similar results were noted for hypotension. In addition, a dose response was observed for both mothers and fathers between preconception time in intensive care and the risk of preterm birth and pregnancy loss.

CONCLUSION(S)

In a pre-COVID-19 cohort, parental preconception severe systemic infection was associated with increased odds of preterm birth and pregnancy loss when conception was soon after the illness.

High-throughput quantitation of serological ceramides/dihydroceramides by LC/MS/MS: Pregnancy baseline biomarkers and potential metabolic messengers

Ceramides and dihydroceramides are sphingolipids that present in abundance at the cellular membrane of eukaryotes. Although their metabolic dysregulation has been implicated in many diseases, our knowledge about circulating ceramide changes during the pregnancy remains limited. In this study, we present the development and validation of a high-throughput liquid chromatography-tandem mass spectrometric method for simultaneous quantification of 16 ceramides and 10 dihydroceramides in human serum within 5 min. by using stable isotope-labeled ceramides as internal standards. This method employs a protein precipitation method for high throughput sample preparation, reverse phase isocratic elusion for chromatographic separation, and Multiple Reaction Monitoring for mass spectrometric detection. To qualify for clinical applications, our assay has been validated against the FDA guidelines for Lower Limit of Quantitation (1 nM), linearity (R²>0.99), precision (imprecision<15 %), accuracy (inaccuracy<15 %), extraction recovery (>90 %), stability (>85 %), and carryover (<0.01 %). With enhanced sensitivity and specificity from this method, we have, for the first time, determined the serological levels of ceramides and dihydroceramides to reveal unique temporal gestational patterns. Our approach could have value in providing insights into disorders of pregnancy.

Cheek support affects lung mechanics measurements of tidal-based spontaneous breathing

BACKGROUND AND OBJECTIVE

Patients are required to support their cheeks during breath-occluding lung function tests. This prevents cheek expansion which would alter pressure measured at the mouth, and, consequently, lung mechanics measurements. To date, the effect of cheek support on airway resistance measurements has been assessed. However other lung mechanics have not been studied as thoroughly, and no algorithm to account for the effect of missing cheek support on lung mechanics measurements has been developed.

METHODS

Lung mechanics were assessed with a breath occlusion test during light panting in healthy subjects with and without cheek support in a body plethysmograph. Average model-based airway resistance, lung elastance, and a parameter representing the viscoelastic were measured. Results were compared to quantify the effect of cheek support on these three parameters.

RESULTS

In the nine healthy subjects (5 Female, 4 Male) recruited for this study, all mechanics tended to be underestimated when cheeks were unsupported. Changes in elastance, resistance, and viscoelastic parameter ranged between 1.6-66.8 %, -4.5-21.8 %, and -4.7-68.2 %, respectively, when cheek support was added. The underestimation was due to reduced mouth pressure during cheek expansion when the breath was occluded. The variance of lung mechanics parameters did not change with cheek support in all subjects.

CONCLUSIONS

The error in lung mechanics measurement caused by unsupported cheeks was subject dependent. Hence, no rule-of-thumb could be identified to reconstruct missing cheek support. For correct lung mechanics measurements during breath-occluding lung tests, patients must have adequate cheek support.

ABBREVIATIONS

ROCC: Occlusion resistance; COPD: Chronic Obstructive Pulmonary Disorder; SB: spontaneous breathing.

Periconceptional stressors and social support and risk for adverse birth outcomes

Background

The prevalence of preterm birth and low birth weight has been increasing slightly in recent years. A few studies have suggested that psychosocial stress during pregnancy may increase risk for these adverse birth outcomes. To extend those observations, we analyzed various major life event stressors separately and cumulatively as potential risk factors for preterm birth and low birth weight using granular categories of each outcome in a large, population-based study. Additionally, we assessed if greater social support buffered any effects.

Methods

Data were from a nested prevalence study of 4395 women in the National Birth Defects Prevention Study who delivered live-born non-malformed infants (controls) between 2006 and 2011. Participants completed a standardized, computer-assisted interview between 6 weeks and 24 months after delivery that included questions on stress and social support from 3 months before pregnancy to the 3rd month of pregnancy. Cumulative stress and support indices were also calculated. Preterm birth was divided into “early preterm” (< 32 weeks), “late preterm” (32–36 weeks) and “term.” Low birthweight was divided into “very low birth weight” (< 1500 g), “low birth weight” (1500–2499 g) and “normal birth weight” (≥2500 g). Relative risks and 95% confidence intervals (95% CI) were calculated using Poisson regression.

Results

For women reporting relationship difficulties, there was a suggestive risk of early preterm birth (RR: 1.9, 95%CI: 0.9–3.9) and very low birthweight (RR: 2.0, 95%CI: 0.9–4.4). For women reporting that they or someone close to them were victims of abuse, violence, or crime, there was an increased risk of low birthweight (RR: 1.8, 95%CI: 1.1–2.7) and late preterm birth (RR: 1.5, 95%CI: 1.0–2.2). There were no strong associations observed between social support questions and the various outcomes.

Conclusions

Our results add some support to prior evidence that certain stressors may be associated with increase selected adverse birth outcomes risk. We did not find strong evidence that social support buffered the observed risks in our study.

Congenital diaphragmatic hernia and maternal dietary nutrient pathways and diet quality

INTRODUCTION

We examined the association of congenital diaphragmatic hernia (CDH) with maternal dietary intake, using semi-Bayes hierarchical models and principal components analysis to consider intake of nutrients that contribute to one-carbon metabolism and oxidative stress pathways, and a diet quality index.

METHODS

We included data on 825 cases and 11,108 nonmalformed controls born from 1997-2011 whose mother participated in the National Birth Defects Prevention Study (NBDPS), a multisite, population-based case-control study. Exposure data were from maternal telephone interviews, which included a food frequency questionnaire. Adjusted odds ratios (aOR) and 95% confidence intervals (CI) were generated from logistic regression models that included nutritional factors as continuous variables and were adjusted for maternal energy intake, race-ethnicity, parity, and vitamin supplement intake.

RESULTS

In the semi-Bayes hierarchical model that included all nutrients and confounders, riboflavin was the only nutrient for which the 95% CI excluded 1.0; the aOR for a 1 SD increase was 0.83. The aORs were 0.79 (95% CI 0.69-0.91) for the one-carbon metabolism pathway score, 0.90 (95% CI 0.80-1.01) for oxidative stress, and 0.85 (95% CI 0.77-0.93) for diet quality (the aORs correspond to a 1 SD increase).

CONCLUSIONS

The findings from this study provide some support for the hypothesis that better prepregnancy nutrition is associated with reduced risk for CDH. These results provide etiologic clues but should be interpreted with caution given the novelty of the investigation.

Racial/ethnic disparities and human milk use in necrotizing enterocolitis

BACKGROUND

The impact of human milk use on racial/ethnic disparities in necrotizing enterocolitis (NEC) incidence is unknown.

METHODS

Trends in NEC incidence and human milk use at discharge were evaluated by race/ethnicity among 47,112 very low birth weight infants born in California from 2008 to 2017. We interrogated the association between race/ethnicity and NEC using multilevel regression analysis, and evaluated the effect of human milk use at discharge on the relationship between race/ethnicity and NEC using mediation analysis.

RESULTS

Annual NEC incidence declined across all racial/ethnic groups from an aggregate average of 4.8% in 2008 to 2.6% in 2017. Human milk use at discharge increased over the time period across all racial groups, and non-Hispanic (NH) black infants received the least human milk each year. In multivariable analyses, Hispanic ethnicity (odds ratio (OR) 1.27, 95% confidence interval (CI) 1.02-1.57) and Asian or Pacific Islander race (OR 1.35, 95% CI 1.01-1.80) were each associated with higher odds of NEC, while the association of NH black race with NEC was attenuated after adding human milk use at discharge to the model. Mediation analysis revealed that human milk use at discharge accounted for 22% of the total risk of NEC in non-white vs. white infants, and 44% in black vs. white infants.

CONCLUSIONS

Although NEC incidence has declined substantially over the past decade, a sizable racial/ethnic disparity persists. Quality improvement initiatives augmenting human milk use may further reduce the incidence of NEC in vulnerable populations.

Oil and gas production and spontaneous preterm birth in the San Joaquin Valley, CA: A case-control study

BACKGROUND

Recent studies report an association between preterm birth and exposure to unconventional oil and gas wells. There has been limited previous study on exposure to conventional wells, which are common in California. Our objective was to determine whether exposure to well sites was associated with increased odds of spontaneous preterm birth (delivery at <37 weeks).

METHODS

We conducted a case-control study using data on 27,913 preterm birth cases and 197,461 term birth controls. All births were without maternal comorbidities and were located in the San Joaquin Valley, CA, between 1998 and 2011. We obtained data for 83,559 wells in preproduction or production during the study period. We assessed exposure using inverse distance-squared weighting and, for each birth and trimester, we assigned an exposure tertile. Using logistic regression, we estimated adjusted odds ratios (ORs) for the association between exposure to well sites and preterm birth at 20-27, 28-31, and 32-36 weeks.

RESULTS

We observed increased ORs for preterm birth with high exposure to wells in the first and second trimesters for births delivered at ≤31 weeks (adjusted ORs, 1.08-1.14). In stratified analyses, the associations were confined to births to Hispanic and non-Hispanic Black women and to women with ≤12 years of educational attainment. In a secondary analysis, we found evidence that exposure to wells in preproduction is associated with higher concentrations of particulate matter.

CONCLUSIONS

We found evidence that exposure to oil and gas well sites is associated with increased risk of spontaneous preterm birth.

Multiomic immune clockworks of pregnancy

Preterm birth is the leading cause of mortality in children under the age of five worldwide. Despite major efforts, we still lack the ability to accurately predict and effectively prevent preterm birth. While multiple factors contribute to preterm labor, dysregulations of immunological adaptations required for the maintenance of a healthy pregnancy is at its pathophysiological core. Consequently, a precise understanding of these chronologically paced immune adaptations and of the biological pacemakers that synchronize the pregnancy "immune clock" is a critical first step towards identifying deviations that are hallmarks of peterm birth. Here, we will review key elements of the fetal, placental, and maternal pacemakers that program the immune clock of pregnancy. We will then emphasize multiomic studies that enable a more integrated view of pregnancy-related immune adaptations. Such multiomic assessments can strengthen the biological plausibility of immunological findings and increase the power of biological signatures predictive of preterm birth.

VoPo leverages cellular heterogeneity for predictive modeling of single-cell data

High-throughput single-cell analysis technologies produce an abundance of data that is critical for profiling the heterogeneity of cellular systems. We introduce VoPo (https://github.com/stanleyn/VoPo), a machine learning algorithm for predictive modeling and comprehensive visualization of the heterogeneity captured in large single-cell datasets. In three mass cytometry datasets, with the largest measuring hundreds of millions of cells over hundreds of samples, VoPo defines phenotypically and functionally homogeneous cell populations. VoPo further outperforms state-of-the-art machine learning algorithms in classification tasks, and identified immune-correlates of clinically-relevant parameters.

Stillbirths and live births in the periviable period

PURPOSE

We use data from California, where 13% of US births occur, to address two questions arising from efforts in the first decade of this century to avoid stillbirths before 25 6/7 weeks of gestation (i.e., in the periviable period). First, did stillbirths decline in the first decade of this century? Second, if stillbirths did decline, did periviable live births increase simultaneously? Answering these questions is important given that periviable infants represent less than 1% of live births but account for roughly 40% of infant mortality and 20% of hospital-based obstetric costs in the United States.

METHODS

We constructed 240 monthly conception cohorts, starting with that conceived in January 1991, from 9,880,536 singleton pregnancies that reached the 20 0/7 week of gestation. We used time-series design and Box-Jenkins methods that address confounding by autocorrelation, including secular trends and seasonality to answer our questions.

RESULTS

We detected a downward shift in stillbirths in April 2007 that coincided with an upward shift in periviable live births.

CONCLUSIONS

Our findings imply that, since 2007, fewer Californians than expected from history and from the size of conception cohorts reaching 20 0/7 weeks of gestation have had to contend with the sequelae of stillbirths, but more than expected likely have had to contend with those of periviable births.

Newborn Iodine Status Is Not Related to Congenital Hypothyroidism

BACKGROUND

Severe iodine deficiency or excess during pregnancy can cause congenital hypothyroidism (CH). Iodine deficiency is common in pregnant women in the United States.

OBJECTIVES

We conducted a nested case-control study in a cohort of ∼2.5 million births in California to determine whether iodine status is related to CH in a US population.

METHODS

Dried blood spots from 907 newborns with CH identified by newborn screening and 909 unaffected controls matched by month of birth were obtained from the California Newborn Screening Program to measure whole-blood iodine concentration. Iodine status was compared between cases and controls, and logistic regression was used to assess the association between CH status and blood iodine concentrations. Iodine status was also compared between cases and controls among infants treated in a neonatal intensive care unit (NICU) because CH has been reported in infants exposed to high levels of iodine in the NICU.

RESULTS

Blood iodine concentrations did not differ significantly between cases (median: 20.0 ng/mL; IQR: 12.1-29.8 ng/mL) and controls (median: 20.3 ng/mL; IQR: 12.5-30.9 ng/mL; P = 0.59). Neither extremely high nor extremely low blood iodine concentrations (1st, 5th, 95th, and 99th percentiles of the distribution) were more common in cases. Among infants treated in NICUs, however, cases had significantly (P = 0.01) higher iodine (median: 22.7 ng/mL; IQR: 16.4-32.1 ng/mL) compared with controls (median: 17.3 ng/mL; IQR: 8.3-26.6 ng/mL).

CONCLUSIONS

CH cases did not have significantly higher or lower iodine in this population, which is reassuring given that maternal iodine deficiency is common in the United States. Among newborns in the NICU, CH cases had higher blood iodine concentrations compared with controls, suggesting that excess iodine exposure in the NICU could be causing CH. It may be beneficial to monitor iodine exposure from surgical procedures, imaging, and iodine-containing disinfectants and to consider non-iodine alternatives.

Maternal occupational exposure to polycyclic aromatic hydrocarbons and the risk of isolated congenital heart defects among offspring

BACKGROUND

Although there is evidence in experimental model systems that exposure to polycyclic aromatic hydrocarbons (PAHs) is linked with congenital heart defects (CHDs), few studies have examined the association in humans. We conducted a case-control study to examine the association between maternal exposure to PAHs and CHDs in offspring using data from the National Birth Defects Prevention Study (NBDPS) (1997-2011).

METHODS

We obtained detailed information on maternal occupation during the month before to three months after conception. Expert raters, masked to case-control status, assessed job descriptions to assign categorical levels of exposure. Categories were quantitatively mapped to estimate cumulative exposure to PAHs, incorporating exposure intensity, frequency, work duration, and work hours. Quartiles were generated for cumulative maternal exposure to PAHs. Crude and adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were estimated using unconditional logistic regression for quartiles of PAH exposure and six CHD groupings (e.g. conotruncal) and specific subtypes (e.g. tetralogy of Fallot [ToF]). Final models were adjusted for maternal age, race/ethnicity, education, smoking, anticonvulsant use, folic acid supplementation, and study center.

RESULTS

There were 4,775 case and 7,734 control infants eligible for the study. The prevalence of occupational exposure to PAHs was 10.2% among both case and control mothers. In adjusted analysis, compared to mothers with no occupational PAH exposure, those in the highest quartile of exposure were more likely to have offspring in the conotruncal heart defects group (OR 1.41; 95% CI 1.00-2.00), and with ToF (OR 1.83; 95% CI 1.21-2.78).

CONCLUSIONS

Women in the highest quartile of estimated cumulative occupational PAH exposure during early pregnancy were more likely to have offspring with conotruncal heart defects, specifically ToF, compared to women with no occupational PAH exposure. Other comparisons between PAHs and other CHDs subgroups did not show any statistically precise associations.

Survival of infants with congenital diaphragmatic hernia in California: impact of hospital, clinical, and sociodemographic factors

OBJECTIVE

To understand factors associated with care and survival among babies with congenital diaphragmatic hernia (CDH).

STUDY DESIGN

We used data on California births (2006-2011) to examine birth hospital level of care, hospital transfer before repair, and survival.

RESULT

Among 577 infants, 25% were born at lower-level hospitals, 62% were transferred, and 31% died during infancy. Late or no prenatal care had the strongest association with birth at lower-level hospitals (adjusted relative risk (ARR) = 1.9, 95% confidence interval (CI) = 1.0-3.6). Birth at lower-level hospitals was associated with transfer (ARR = 1.2, CI = 1.1-1.4), and transferred infants tended to be less clinically complex. Infants with low birthweight, other birth defects, low Apgar scores, and late or no prenatal care had two- to fourfold higher risk of mortality than their comparison groups.

CONCLUSIONS

These data support the importance of prenatal care and delivery planning into higher-level hospitals for optimal care and outcomes for newborns with CDH.

Male-to-female ratios among NTDs and women's periconceptional intake of folic acid

BACKGROUND

About a decade ago, a hypothesis was put forward to explain the preponderance of females among neural tube defect (NTD) fetuses. That hypothesis predicts that a woman's higher levels of early gestational intake of methyl groups, such as folic acid, will be associated with lesser male-to-female ratio differences in NTD-affected births, specifically less preponderance of females. We explored this hypothesis in four distinct studies that investigated human NTDs, obtained information on folic acid, and capitalized on timing of folic acid fortification by investigating data that were collected both prior to and after the 1998 initiation of U.S. mandatory folic acid fortification of grains.

METHODS

We analyzed data from four population-based case control studies conducted in California for birth years spanning 1987-2011. Two studies were conducted before folic acid fortification of the U.S. food supply. Each of the four studies included interviews of women who either had NTD-affected pregnancies (cases) or who did not have a pregnancy affected by a birth defect (controls). In each study, information on periconceptional supplement use was elicited. We explored male-to-female ratios and 95% binomial confidence limits in each data set.

RESULTS

Our analyses of two case-control studies performed prior to and two performed post mandatory folate fortification in the United States showed that more NTD-affected fetuses were female in the first two studies. In the studies done before fortification, the frequency of females was even greater among those pregnancies without folic acid supplementation.

CONCLUSION

Our findings suggest folic acid may differentially reduce risk of NTDs among female fetuses.

Preterm birth outcomes among Asian women by maternal place of birth

OBJECTIVE

To investigate overall, spontaneous, and medically indicated preterm birth (PTB) rates between US-born and non-US-born Asian women living in California.

STUDY DESIGN

Nulliparous women with a singleton livebirth and Asian race in California between 2007 and 2011 were investigated. The prevalence of overall (<37 weeks), spontaneous, and medically indicated PTB was examined by self-reported race and place of birth among ten Asian subgroups.

RESULTS

There were marked differences in PTB rates between the individual Asian subgroups. After adjustments, non-US-born Chinese, Japanese, Vietnamese, and Indian women had lower odds of overall PTB and Chinese, Vietnamese, Cambodian, and Indian women had lower odds of spontaneous PTB compared with their US-born counterparts.

CONCLUSION

Further investigation of biological and social factors contributing to these lower odds of spontaneous PTB among the non-US-born Asian population could potentially offer clues for reducing the burden of PTB among the US born.

Inspiratory respiratory mechanics estimation by using expiratory data for reverse-triggered breathing cycles

BACKGROUND AND OBJECTIVE

Model-based lung mechanics monitoring can provide clinically useful information for guiding mechanical ventilator treatment in intensive care. However, many methods of measuring lung mechanics are not appropriate for both fully and partially sedated patients, and are unable provide lung mechanics metrics in real-time. This study proposes a novel method of using lung mechanics identified during passive expiration to estimate inspiratory lung mechanics for spontaneously breathing patients.

METHODS

Relationships between inspiratory and expiratory modeled lung mechanics were identified from clinical data from 4 fully sedated patients. The validity of these relationships were assessed using data from a further 4 spontaneously breathing patients.

RESULTS

For the fully sedated patients, a linear relationship was identified between inspiratory and expiratory elastance, with slope 1.04 and intercept 1.66. The r value of this correlation was 0.94. No cohort-wide relationship was determined for airway resistance. Expiratory elastance measurements in spontaneously breathing patients were able to produce reasonable estimates of inspiratory elastance after adjusting for the identified difference between them.

CONCLUSIONS

This study shows that when conventional methods fail, typically ignored expiratory data may be able to provide clinicians with the information needed about patient condition to guide MV therapy.

Changes in pregnancy-related serum biomarkers early in gestation are associated with later development of preeclampsia

Background

Placental protein expression plays a crucial role during pregnancy. We hypothesized that: (1) circulating levels of pregnancy-associated, placenta-related proteins throughout gestation reflect the temporal progression of the uncomplicated, full-term pregnancy, and can effectively estimate gestational ages (GAs); and (2) preeclampsia (PE) is associated with disruptions in these protein levels early in gestation; and can identify impending PE. We also compared gestational profiles of proteins in the human and mouse, using pregnant heme oxygenase-1 (HO-1) heterozygote (Het) mice, a mouse model reflecting PE-like symptoms.

Methods

Serum levels of placenta-related proteins–leptin (LEP), chorionic somatomammotropin hormone like 1 (CSHL1), elabela (ELA), activin A, soluble fms-like tyrosine kinase 1 (sFlt-1), and placental growth factor (PlGF)–were quantified by ELISA in blood serially collected throughout human pregnancies (20 normal subjects with 66 samples, and 20 subjects who developed PE with 61 samples). Multivariate analysis was performed to estimate the GA in normal pregnancy. Mean-squared errors of GA estimations were used to identify impending PE. The human protein profiles were then compared with those in the pregnant HO-1 Het mice.

Results

An elastic net-based gestational dating model was developed (R² = 0.76) and validated (R² = 0.61) using serum levels of the 6 proteins measured at various GAs from women with normal uncomplicated pregnancies. In women who developed PE, the model was not (R² = -0.17) associated with GA. Deviations from the model estimations were observed in women who developed PE (P = 0.01). The model developed with 5 proteins (ELA excluded) performed similarly from sera from normal human (R² = 0.68) and WT mouse (R² = 0.85) pregnancies. Disruptions of this model were observed in both human PE-associated (R² = 0.27) and mouse HO-1 Het (R² = 0.30) pregnancies. LEP outperformed sFlt-1 and PlGF in differentiating impending PE at early human and late mouse GAs.

Conclusions

Serum placenta-related protein profiles are temporally regulated throughout normal pregnancies and significantly disrupted in women who develop PE. LEP changes earlier than the well-established biomarkers (sFlt-1 and PlGF). There may be evidence of a causative action of HO-1 deficiency in LEP upregulation in a PE-like murine model.

Substantial Cardiovascular Morbidity in Adults With Lower-Complexity Congenital Heart Disease

BACKGROUND

Although lower-complexity cardiac malformations constitute the majority of adult congenital heart disease (ACHD), the long-term risks of adverse cardiovascular events and relationship with conventional risk factors in this population are poorly understood. We aimed to quantify the risk of adverse cardiovascular events associated with lower-complexity ACHD that is unmeasured by conventional risk factors.

METHODS

A multitiered classification algorithm was used to select individuals with lower-complexity ACHD and individuals without ACHD for comparison among >500 000 British adults in the UK Biobank. ACHD diagnoses were subclassified as isolated aortic valve and noncomplex defects. Time-to-event analyses were conducted for the primary end points of fatal or nonfatal acute coronary syndrome, ischemic stroke, heart failure, and atrial fibrillation and a secondary combined end point for major adverse cardiovascular events. Maximum follow-up time for the study period was 22 years with retrospectively and prospectively collected data from the UK Biobank.

RESULTS

We identified 2006 individuals with lower-complexity ACHD and 497 983 unexposed individuals in the UK Biobank (median age at enrollment, 58 [interquartile range, 51-63] years). Of the ACHD-exposed group, 59% were male, 51% were current or former smokers, 30% were obese, and 69%, 41%, and 7% were diagnosed or treated for hypertension, hyperlipidemia, and diabetes mellitus, respectively. After adjustment for 12 measured cardiovascular risk factors, ACHD remained strongly associated with the primary end points, with hazard ratios ranging from 2.0 (95% CI, 1.5-2.8; P<0.001) for acute coronary syndrome to 13.0 (95% CI, 9.4-18.1; P<0.001) for heart failure. ACHD-exposed individuals with ≤2 cardiovascular risk factors had a 29% age-adjusted incidence rate of major adverse cardiovascular events, in contrast to 13% in individuals without ACHD with ≥5 risk factors.

CONCLUSIONS

Individuals with lower-complexity ACHD had a higher burden of adverse cardiovascular events relative to the general population that was unaccounted for by conventional cardiovascular risk factors. These findings highlight the need for closer surveillance of patients with mild to moderate ACHD and further investigation into management and mechanisms of cardiovascular risk unique to this growing population of high-risk adults.

The TFAP2A-IRF6-GRHL3 genetic pathway is conserved in neurulation

Mutations in IRF6, TFAP2A and GRHL3 cause orofacial clefting syndromes in humans. However, Tfap2a and Grhl3 are also required for neurulation in mice. Here, we found that homeostasis of Irf6 is also required for development of the neural tube and associated structures. Over-expression of Irf6 caused exencephaly, a rostral neural tube defect, through suppression of Tfap2a and Grhl3 expression. Conversely, loss of Irf6 function caused a curly tail and coincided with a reduction of Tfap2a and Grhl3 expression in tail tissues. To test whether Irf6 function in neurulation was conserved, we sequenced samples obtained from human cases of spina bifida and anencephaly. We found two likely disease-causing variants in two samples from patients with spina bifida. Overall, these data suggest that the Tfap2a-Irf6-Grhl3 genetic pathway is shared by two embryologically distinct morphogenetic events that previously were considered independent during mammalian development. In addition, these data suggest new candidates to delineate the genetic architecture of neural tube defects and new therapeutic targets to prevent this common birth defect.

Loss of RAD9B impairs early neural development and contributes to the risk for human spina bifida

DNA damage response (DDR) genes orchestrating the network of DNA repair, cell cycle control, are essential for the rapid proliferation of neural progenitor cells. To date, the potential association between specific DDR genes and the risk of human neural tube defects (NTDs) has not been investigated. Using whole-genome sequencing and targeted sequencing, we identified significant enrichment of rare deleterious RAD9B variants in spina bifida cases compared to controls (8/409 vs. 0/298; p = .0241). Among the eight identified variants, the two frameshift mutants and p.Gln146Glu affected RAD9B nuclear localization. The two frameshift mutants also decreased the protein level of RAD9B. p.Ser354Gly, as well as the two frameshifts, affected the cell proliferation rate. Finally, p.Ser354Gly, p.Ser10Gly, p.Ile112Met, p.Gln146Glu, and the two frameshift variants showed a decreased ability for activating JNK phosphorylation. RAD9B knockdowns in human embryonic stem cells profoundly affected early differentiation through impairing PAX6 and OCT4 expression. RAD9B deficiency impeded in vitro formation of neural organoids, a 3D cell culture model for human neural development. Furthermore, the RNA-seq data revealed that loss of RAD9B dysregulates cell adhesion genes during organoid formation. These results represent the first demonstration of a DDR gene as an NTD risk factor in humans.

Investigating Pregnancy and Its Complications Using Circulating Cell-Free RNA in Women's Blood During Gestation

In recent years, there have been major advances in the application of non-invasive techniques to predict pregnancy-related complications, for example by measuring cell-free RNA (cfRNA) in maternal blood. In contrast to cell-free DNA (cfDNA), which is already in clinical use to diagnose fetal aneuploidy, circulating RNA levels can correspond with tissue-specific gene expression and provide a snapshot of prenatal health across gestation. Here, we review the physiologic origins of cfRNA and its novel applications and corresponding challenges to monitor fetal and maternal health and predict pregnancy-related complications.

Associations between fine particulate matter, extreme heat events, and congenital heart defects

Previous research reports associations between air pollution measured during pregnancy and the occurrence of congenital heart defects (CHDs) in offspring. The objective of this research was to assess if exposure to extreme heat events (EHEs) during pregnancy may modify this association.

METHODS

The study population consisted of 4,033 controls and 2,632 cases with dates of delivery between 1999 and 2007 who participated in the National Birth Defects Prevention Study, a multi-site case-control study in the United States. Daily data from the closest stationary fine particulate matter (PM2.5) monitor within 50 km from the maternal residence were averaged across weeks 3-8 post-conception. EHEs were defined as maximum ambient temperature in the upper 95th percentile for at least 2 consecutive days or the upper 90th percentile for 3 consecutive days. Logistic regression models were adjusted for maternal age, ethnicity, education, and average humidity. Relative excess risks due to interaction (RERI) were calculated.

RESULTS

Compared with women with low PM2.5 exposure and no exposure to an EHE, the odds of a ventricular septal defect in offspring associated with high PM2.5 exposure was elevated only among women who experienced an EHE (odds ratio [OR] 2.14 95% confidence interval [CI] 1.19, 3.38 vs. OR 0.97 95% CI 0.49, 1.95; RERI 0.82 95% CI -0.39, 2.17). The majority of observed associations and interactions for other heart defects were null and/or inconclusive due to lack of precision.

CONCLUSIONS

This study provides limited evidence that EHEs may modify the association between prenatal exposure to PM2.5 and CHD occurrence.

Maternal exposure to outdoor air pollution and congenital limb deficiencies in the National Birth Defects Prevention Study

BACKGROUND

Congenital limb deficiencies (CLDs) are a relatively common group of birth defects whose etiology is mostly unknown. Recent studies suggest maternal air pollution exposure as a potential risk factor.

AIM

To investigate the relationship between ambient air pollution exposure during early pregnancy and offspring CLDs.

METHODS

The study population was identified from the National Birth Defects Prevention Study, a population-based multi-center case-control study, and consisted of 615 CLD cases and 5,701 controls with due dates during 1997 through 2006. Daily averages and/or maxima of six criteria air pollutants (particulate matter <2.5 μm [PM_2.5], particulate matter <10 μm [PM₁₀], nitrogen dioxide [NO₂], sulfur dioxide [SO₂], carbon monoxide [CO], and ozone [O₃]) were averaged over gestational weeks 2-8, as well as for individual weeks during this period, using data from EPA air monitors nearest to the maternal address. Logistic regression was used to estimate odds ratios (aORs) and 95% confidence intervals (CIs) adjusted for maternal age, race/ethnicity, education, and study center. We estimated aORs for any CLD and CLD subtypes (i.e., transverse, longitudinal, and preaxial). Potential confounding by co-pollutant was assessed by adjusting for one additional air pollutant. Using the single pollutant model, we further investigated effect measure modification by body mass index, cigarette smoking, and folic acid use. Sensitivity analyses were conducted restricting to those with a residence closer to an air monitor.

RESULTS

We observed near-null aORs for CLDs per interquartile range (IQR) increase in PM₁₀, PM_2.5, and O₃. However, weekly averages of the daily average NO₂ and SO₂, and daily max NO₂, SO₂, and CO concentrations were associated with increased odds of CLDs. The crude ORs ranged from 1.03 to 1.12 per IQR increase in these air pollution concentrations, and consistently elevated aORs were observed for CO. Stronger associations were observed for SO₂ and O₃ in subtype analysis (preaxial). In co-pollutant adjusted models, associations with CO remained elevated (aORs: 1.02-1.30); but aORs for SO₂ and NO₂ became near-null. The aORs for CO remained elevated among mothers who lived within 20 km of an air monitor. The aORs varied by maternal BMI, smoking status, and folic acid use.

CONCLUSION

We observed modest associations between CLDs and air pollution exposures during pregnancy, including CO, SO₂, and NO₂, though replication through further epidemiologic research is warranted.

A Genome-Wide Analysis of Clinical Chorioamnionitis among Preterm Infants

OBJECTIVE

To identify single nucleotide polymorphisms (SNPs) associated with clinical chorioamnionitis among preterm infants.

STUDY DESIGN

We reanalyzed a genome-wide association study (GWAS) from preterm newborns at less than 30 weeks' gestation. Cases and control definitions were determined using administrative records. There were 213 clinical chorioamnionitis cases and 707 clinically uninfected controls. We compared demographic and clinical outcomes of cases and controls. We performed a GWAS and compared the distribution of SNPs from the background genes and from the immunome genes. We used a Wilcoxon's rank-sum test to compare the SNPs normalized odds ratio and used odds ratios and p-values to determine candidate genes.

RESULTS

Infants affected by clinical chorioamnionitis were more likely to have periventricular leukomalacia, high-grade retinopathy, and high-grade intraventricular hemorrhage (IVH). Although a GWAS did not identify SNPs associated with clinical chorioamnionitis at the genome-wide significance level, a direct test on the exonic variants in the human immunome revealed their significant increase of risk in clinical chorioamnionitis.

CONCLUSION

Among very preterm infants, clinical chorioamnionitis was associated with periventricular leukomalacia, high-grade retinopathy, and IVH. Our analysis of variants in the human immunome indicates an association with clinical chorioamnionitis in very preterm pregnancies.

Associations between PM2.5 and risk of preterm birth among liveborn infants

PURPOSE

Studies suggest exposure to ambient particulate matter less than 2.5 μg/m3 in aerodynamic diameter (PM2.5) may be associated with preterm birth (PTB), but few have evaluated how this is modified by ambient temperature. We investigated the relationship between PM2.5 exposure during pregnancy and PTB in infants without birth defects (1999-2006) and enrolled in the National Birth Defects Prevention Study and how it is modified by concurrent temperature.

METHODS

PTB was defined as spontaneous or iatrogenic delivery before 37 weeks. Exposure was assigned using inverse distance weighting with up to four monitors within 50 kilometers of maternal residence. To account for state-level variations, a Bayesian two-level hierarchal model was developed.

RESULTS

PTB was associated with PM2.5 during the third and fourth months of pregnancy (range: (odds ratio (95% confidence interval) = 1.00 (0.35, 2.15) to 1.49 (0.82, 2.68) and 1.31 (0.56, 2.91) to 1.62 (0.7, 3.32), respectively); no week of exposure conveyed greater risk. Temperature may modify this relationship; higher local average temperatures during pregnancy yielded stronger positive relationships between PM2.5 and PTB compared to nonstratified results.

CONCLUSIONS

Results add to literature on associations between PM2.5 and PTB, underscoring the importance of considering co-exposures when estimating effects of PM2.5 exposure during pregnancy.

Preterm birth phenotypes in women with autoimmune rheumatic diseases: a population-based cohort study

OBJECTIVE

To investigate preterm birth (PTB) phenotypes in women with different autoimmune rheumatic diseases in a large population-based cohort.

DESIGN

Retrospective cohort study.

SETTING

California, USA.

POPULATION

All live singleton births in California between 2007 and 2011 were analysed. Patients with autoimmune disease at delivery were identified by International Classification of Diseases, Ninth Revision , Clinical Modification (ICD-9-CM), codes for systemic lupus erythematosus (SLE), systemic sclerosis (SSc), rheumatoid arthritis (RA), polymyositis/dermatomyositis (DM/PM), and juvenile idiopathic arthritis (JIA).

METHODS

Maternally linked hospital and birth certificate records of 2 481 516 deliveries were assessed (SLE n = 2272, RA n = 1501, SSc n = 88, JIA n = 187, DM/PM n = 38). Multivariable Poisson regression models estimated the risk ratios (RRs) for different PTB phenotypes (relative to term deliveries) for each autoimmune disease compared with the general obstetric population, adjusting for maternal age, race/ethnicity, body mass index, smoking, education, payer, parity, and prenatal care.

MAIN OUTCOME MEASURES

Preterm birth (PTB) was assessed overall (20-36 weeks of gestation) and by subphenotype: preterm prelabour rupture of membranes (PPROM), spontaneous birth, or medically indicated PTB. The risk of PTB overall and for each phenotype was partitioned by gestational age: early (20-31 weeks of gestation) and late (32-36 weeks of gestation).

RESULTS

Risks for PTB were elevated for each autoimmune disease evaluated: SLE (RR 3.27, 95% CI 3.01-3.56), RA (RR 2.04, 95% CI 1.79-2.33), SSc (RR 3.74, 95% CI 2.51-5.58), JIA (RR 2.23, 95% CI 1.54-3.23), and DM/PM (RR 5.26, 95% CI 3.12-8.89). These elevated risks were observed for the majority of PTB phenotypes as well.

CONCLUSIONS

Women with systemic autoimmune diseases appear to have an elevated risk of various PTB phenotypes. Therefore, preconception counselling and close monitoring during pregnancy is crucial.

TWEETABLE ABSTRACT

This study found that women with systemic autoimmune diseases have an elevated risk of preterm birth phenotypes.

Disease burden in offspring is associated with changing paternal demographics in the United States

BACKGROUND

Average paternal age in the United States has increased substantially in the last few decades. Children of advanced age fathers have a higher incidence of early onset cancer and neuropsychiatric disease.

OBJECTIVES

To quantify the number of population adjusted cases of early-onset cancer and neuropsychiatric disease in children attributable to increasing paternal age in the United States.

METHODS

Paternal age in the United States from 1972 to 2015 was collected using the National Vital Statistics System (NVSS). Population attributable fraction and paternal age-specific cumulative incidence rates of several cancers and neuropsychiatric disorders were obtained from peer-reviewed publications. Paternal age-specific birth rates were correlated with paternal age-specific cumulative incidence rates to determine the number of attributable cases of disease caused by advancing age of fathers in the United States.

RESULTS

The 2015 birth cohort in the United States is estimated to expect 9.2% more cases of acute lymphoblastic leukemia (ALL) diagnosed before 16 years of age (157 additional cases), 13.2% more cases of embryonal tumors in children <5 years of age (209 additional cases), and 13.0% more cases of breast cancer in females younger than 40 years old (424 additional cases) compared to the 1972 birth cohort. We can estimate to expect 10.5% more cases of schizophrenia diagnosed before 21 years of age (2864 additional cases), 6.3% more cases of autism spectrum disorder (ASD) in adolescents <17 years of age (2934 additional cases), 4.5% more cases of anorexia nervosa (AN) in females 8-30 years old (620 additional cases), and 9.2% more cases of bipolar disorder in young patients 16-25 years old (252 additional cases) in the 2015 birth cohort compared to the 1972 birth cohort.

CONCLUSION

Increasing paternal age in the United States is associated with a substantial increase in the number of cases of early-onset cancer and neuropsychiatric disease in offspring.

Data-driven queries between medications and spontaneous preterm birth among 2.5 million pregnancies

BACKGROUND

Our goal was to develop an approach that can systematically identify potential associations between medication prescribed in pregnancy and spontaneous preterm birth (sPTB) by mining large administrative "claims" databases containing hundreds of medications. One such association that we illustrate emerged with antiviral medications used for herpes treatment.

METHODS

IBM MarketScan® databases (2007-2016) were used. A pregnancy cohort was established using International Classification of Diseases (ICD-9/10) codes. Multiple hypothesis testing and the Benjamini-Hochberg procedure that limited false discovery rate at 5% revealed, among 863 medications, five that showed odds ratios (ORs) <1. The statistically strongest was an association between antivirals and sPTB that we illustrate as a real example of our approach, specifically for treatment of genital herpes (GH). Three groups of women were identified based on diagnosis of GH and treatment during the first 36 weeks of pregnancy: (a) GH without treatment; (b) GH treated with antivirals; (c) no GH or treatment.

RESULTS

We identified 2,538,255 deliveries. 0.98% women had a diagnosis of GH. Among them, 60.0% received antiviral treatment. Women with treated GH had OR < 1, (OR [95% CI] = 0.91 [0.85, 0.98]). In contrast, women with untreated GH had a small increased risk of sPTB (OR [95% CI] =1.22 [1.14, 1.32]).

CONCLUSIONS

Data-driven approaches can effectively generate new hypotheses on associations between medications and sPTB. This analysis led us to examine the association with GH treatment. While unknown confounders may impact these findings, our results indicate that women with untreated GH have a modest increased risk of sPTB.

Exome sequencing of family trios from the National Birth Defects Prevention Study: Tapping into a rich resource of genetic and environmental data

BACKGROUND

The National Birth Defects Prevention Study (NBDPS) is a multisite, population-based, case-control study of genetic and nongenetic risk factors for major structural birth defects. Eligible women had a pregnancy affected by a birth defect or a liveborn child without a birth defect between 1997 and 2011. They were invited to complete a telephone interview to collect pregnancy exposure data and were mailed buccal cell collection kits to collect specimens from themselves, their child (if living), and their child's father. Over 23,000 families representing more than 30 major structural birth defects provided DNA specimens.

METHODS

To evaluate their utility for exome sequencing (ES), specimens from 20 children with colonic atresia were studied. Evaluations were conducted on specimens collected using cytobrushes stored and transported in open versus closed packaging, on native genomic DNA (gDNA) versus whole genome amplified (WGA) products and on a library preparation protocol adapted to low amounts of DNA.

RESULTS

The DNA extracted from brushes in open packaging yielded higher quality sequence data than DNA from brushes in closed packaging. Quality metrics of sequenced gDNA were consistently higher than metrics from corresponding WGA products and were consistently high when using a low input protocol.

CONCLUSIONS

This proof-of-principle study established conditions under which ES can be applied to NBDPS specimens. Successful sequencing of exomes from well-characterized NBDPS families indicated that this unique collection can be used to investigate the roles of genetic variation and gene-environment interaction effects in birth defect etiologies, providing a valuable resource for birth defect researchers.

Sociodemographic, health behavioral, and clinical risk factors for anotia/microtia in a population-based case-control study

OBJECTIVE

Anotia and microtia are congenital malformations of the external ear with few known risk factors. We conducted a comprehensive assessment of a wide range of potential risk factors using data from the National Birth Defects Prevention Study (NBDPS), a population-based case-control study of non-chromosomal structural birth defects in the United States.

METHODS

Mothers of 699 infants with anotia or microtia (cases) and 11,797 non-malformed infants (controls) delivered between 1997 and 2011 were interviewed to obtain information about sociodemographic, health behavioral, and clinical characteristics. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were estimated with logistic regression.

RESULTS

Infants with anotia/microtia were more likely to be male (aOR, 1.29; 95% CI, 1.10-1.50) and from a multifetal pregnancy (aOR, 1.68; 95% CI, 1.16-2.42). Cases were also more likely to have parents of Hispanic ethnicity (maternal aOR, 3.19; 95% CI, 2.61-3.91; paternal aOR, 2.11; 95% CI, 1.54-2.88), and parents born outside the United States (maternal aOR, 1.29; 95% CI, 1.06-1.57; paternal aOR, 1.92; 95% CI, 1.53-2.41). Maternal health conditions associated with increased odds of anotia/microtia included obesity (aOR, 1.31; 95% CI, 1.06-1.61) and pre-pregnancy diabetes (type I aOR, 9.89; 95% CI, 5.46-17.92; type II aOR, 4.70; 95% CI, 2.56-8.63). Reduced odds were observed for black mothers (aOR, 0.57; 95% CI, 0.38-0.85) and mothers reporting daily intake of folic acid-containing supplements (aOR, 0.59; 95% CI, 0.46-0.76).

CONCLUSION

We identified several risk factors for anotia/microtia, some which have been previously reported (e.g., diabetes) and others which we investigate for perhaps the first time (e.g., binge drinking) that warrant further investigation. Our findings point to some potentially modifiable risk factors and provide further leads toward understanding the etiology of anotia/microtia.

Preterm Delivery Phenotypes in Systemic Lupus Erythematosus Pregnancies

OBJECTIVE

Women with systemic lupus erythematosus (SLE) are at a greater risk of preterm delivery, many of which may be medically indicated (iatrogenic). We investigated preterm delivery phenotypes in SLE and general population comparators and assessed the role of preeclampsia.

STUDY DESIGN

We used population-based Swedish Register data (2001-2013) and defined maternal SLE as ≥2 SLE-coded discharge diagnoses from the Patient Register with ≥1 coded by an appropriate specialist. Women from the general population were identified using the Total Population Register. Preterm delivery was defined as <37 weeks and separated into spontaneous and iatrogenic, as well as later versus extremely preterm (32 to <37 weeks vs. <32 weeks). Maternal comorbidity was assessed, and the proportion mediated by preeclampsia was calculated examining first, subsequent, and all pregnancies.

RESULTS

Preterm delivery was more common in SLE for the first (22 vs. 6%) and subsequent (15 vs. 4%) pregnancies among 781 SLE-exposed pregnancies and 11,271 non-SLE pregnancies. Of SLE-exposed first births, 27% delivered before 32 weeks, and 90% were iatrogenic (compared with 47% of non-SLE first births).

CONCLUSION

Preterm delivery complicates a greater proportion of SLE pregnancies than general population pregnancies, and a considerable proportion of risk is mediated through preeclampsia.

Maternal Height and Risk of Preeclampsia among Race/Ethnic Groups

OBJECTIVE

Shorter maternal height has been associated with preeclampsia risk in several populations. It has been less evident whether an independent contribution to the risk exists from maternal height consistently across different races/ethnicities. We investigated associations between maternal height and risk of preeclampsia for different races/ethnicities.

STUDY DESIGN

California singleton live births from 2007 to 2011 were analyzed. Logistic regression was used to estimate adjusted odds ratios for the association between height and preeclampsia after stratification by race/ethnicity. To determine the contribution of height that is as independent of body composition as possible, we performed one analysis adjusted for body mass index (BMI) and the other for weight. Additional analyses were performed stratified by parity, and the presence of preexisting/gestational diabetes and autoimmune conditions.

RESULTS

Among 2,138,012 deliveries, 3.1% preeclampsia/eclampsia cases were observed. The analysis, adjusted for prepregnancy weight, revealed an inverse relation between maternal height and risk of mild and severe preeclampsia/eclampsia. When the analysis was adjusted for BMI, an inverse relation between maternal height was observed for severe preeclampsia/eclampsia. These associations were observed for each race/ethnicity.

CONCLUSION

Using a large and diverse cohort, we demonstrated that shorter height, irrespective of prepregnancy weight or BMI, is associated with an increased risk of severe preeclampsia/eclampsia across different races/ethnicities.

Differential Dynamics of the Maternal Immune System in Healthy Pregnancy and Preeclampsia

Preeclampsia is one of the most severe pregnancy complications and a leading cause of maternal death. However, early diagnosis of preeclampsia remains a clinical challenge. Alterations in the normal immune adaptations necessary for the maintenance of a healthy pregnancy are central features of preeclampsia. However, prior analyses primarily focused on the static assessment of select immune cell subsets have provided limited information for the prediction of preeclampsia. Here, we used a high-dimensional mass cytometry immunoassay to characterize the dynamic changes of over 370 immune cell features (including cell distribution and functional responses) in maternal blood during healthy and preeclamptic pregnancies. We found a set of eight cell-specific immune features that accurately identified patients well before the clinical diagnosis of preeclampsia (median area under the curve (AUC) 0.91, interquartile range [0.82-0.92]). Several features recapitulated previously known immune dysfunctions in preeclampsia, such as elevated pro-inflammatory innate immune responses early in pregnancy and impaired regulatory T (Treg) cell signaling. The analysis revealed additional novel immune responses that were strongly associated with, and preceded the onset of preeclampsia, notably abnormal STAT5ab signaling dynamics in CD4⁺T cell subsets (AUC 0.92, p = 8.0E-5). These results provide a global readout of the dynamics of the maternal immune system early in pregnancy and lay the groundwork for identifying clinically-relevant immune dysfunctions for the prediction and prevention of preeclampsia.

Dominant negative GPR161 rare variants are risk factors of human spina bifida

Spina bifida (SB) is a complex disorder of failed neural tube closure during the first month of human gestation, with a suspected etiology involving multiple gene and environmental interactions. GPR161 is a ciliary G-protein coupled receptor that regulates Sonic Hedgehog (Shh) signaling. Gpr161 null and hypomorphic mutations cause neural tube defects (NTDs) in mouse models. Herein we show that several genes involved in Shh and Wnt signaling were differentially expressed in the Gpr161 null embryos using RNA-seq analysis. To determine whether there exists an association between GPR161 and SB in humans, we performed direct Sanger sequencing on the GPR161 gene in a cohort of 384 SB patients and 190 healthy controls. We identified six rare variants of GPR161 in six SB cases, of which two of the variants were novel and did not exist in any databases. Both of these variants were predicted to be damaging by SIFT and/or PolyPhen analysis. The novel GPR161 rare variants mislocalized to the primary cilia, dysregulated Shh and Wnt signaling and inhibited cell proliferation in vitro. Our results demonstrate that GPR161 mutations cause NTDs via dysregulation of Shh and Wnt signaling in mice, and novel rare variants of GPR161 can be risk factors for SB in humans.

Genetic variation in biotransformation enzymes, air pollution exposures, and risk of spina bifida

Spina bifida is a birth defect characterized by incomplete closure of the embryonic neural tube. Genetic factors as well as environmental factors have been observed to influence risks for spina bifida. Few studies have investigated possible gene-environment interactions that could contribute to spina bifida risk. The aim of this study is to examine the interaction between gene variants in biotransformation enzyme pathways and ambient air pollution exposures and risk of spina bifida. We evaluated the role of air pollution exposure during pregnancy and gene variants of biotransformation enzymes from bloodspots and buccal cells in a California population-based case-control (86 cases of spina bifida and 208 non-malformed controls) study. We considered race/ethnicity and folic acid vitamin use as potential effect modifiers and adjusted for those factors and smoking. We observed gene-environment interactions between each of the five pollutants and several gene variants: NO (ABCC2), NO₂ (ABCC2, SLC01B1), PM₁₀ (ABCC2, CYP1A1, CYP2B6, CYP2C19, CYP2D6, NAT2, SLC01B1, SLC01B3), PM_2.5 (CYP1A1 and CYP1A2). These analyses show positive interactions between air pollution exposure during early pregnancy and gene variants associated with metabolizing enzymes. These exploratory results suggest that some individuals based on their genetic background may be more susceptible to the adverse effects of pollution.

Single Cell Transcriptomes Derived from Human Cervical and Uterine Tissue during Pregnancy

This work presents the workflow for generating single cell transcriptomes derived from primary human uterine and cervical tissue obtained during planned cesarean hysterectomies. In total, a catalogue of 310 single cell transcriptomes are obtained, cell types present in these biopsies are inferred, and specific genes defining each of the cellular types present in the tissue are identified. Further validation of the inferred cell identity is also demonstrated via meta-analysis of independent repositories in literature generated by bulk sequenced data of fluorescence-activated cell sorting sorted cells.

Accumulation of rare coding variants in genes implicated in risk of human cleft lip with or without cleft palate

Cleft lip with/without cleft palate (CLP) is a common craniofacial malformation with complex etiologies, reflecting both genetic and environmental factors. Most of the suspected genetic risk for CLP has yet to be identified. To further classify risk loci and estimate the contribution of rare variants, we sequenced the exons in 49 candidate genes in 323 CLP cases and 211 nonmalformed controls. Our findings indicated that rare, protein-altering variants displayed markedly higher burdens in CLP cases at relevant loci. First, putative loss-of-function mutations (nonsense, frameshift) were significantly enriched among cases: 13 of 323 cases (~4%) harbored such alleles within these 49 genes, versus one such change in controls (p = 0.01). Second, in gene-level analyses, the burden of rare alleles showed greater case-association for several genes previously implicated in cleft risk. For example, BHMT displayed a 10-fold increase in protein-altering variants in CLP cases (p = .03), including multiple case occurrences of a rare frameshift mutation (K400 fs). Other loci with greater rare, coding allele burdens in cases were in signaling pathways relevant to craniofacial development (WNT9B, BMP4, BMPR1B) as well as the methionine cycle (MTRR). We conclude that rare coding variants may confer risk for isolated CLP.