Proportion of Orofacial Clefts Attributable to Recognized Risk Factors

OBJECTIVE

Estimate the population attributable fraction (PAF) for a set of recognized risk factors for orofacial clefts.

DESIGN

We used data from the National Birth Defects Prevention Study. For recognized risk factors for which data were available, we estimated crude population attributable fractions (cPAFs) to account for potential confounding, average-adjusted population attributable fractions (aaPAFs). We assessed 11 modifiable and 3 nonmodifiable parental/maternal risk factors. The aaPAF for individual risk factors and the total aaPAF for the set of risk factors were calculated using a method described by Eide and Geffler.

SETTING

Population-based case-control study in 10 US states.

PARTICIPANTS

Two thousand seven hundred seventy-nine cases with isolated cleft lip with or without cleft palate (CL±P), 1310 cases with isolated cleft palate (CP), and 11 692 controls with estimated dates of delivery between October 1, 1997, and December 31, 2011.

MAIN OUTCOME MEASURES

Crude population attributable fraction and aaPAF.

RESULTS

The proportion of CL±P and CP cases attributable to the full set of examined risk factors was 50% and 43%, respectively. The modifiable factor with the largest aaPAF was smoking during the month before pregnancy or the first month of pregnancy (4.0% for CL±P and 3.4% for CP). Among nonmodifiable factors, the factor with the largest aaPAF for CL±P was male sex (27%) and for CP it was female sex (16%).

CONCLUSIONS

Our results may inform research and prevention efforts. A large proportion of orofacial cleft risk is attributable to nonmodifiable factors; it is important to better understand the mechanisms involved for these factors.

Pre-Zika descriptive epidemiology of microcephaly in Texas, 2008-2012

BACKGROUND

There are limited population-based studies on microcephaly. We characterized the epidemiology of microcephaly in Texas during a 5-year period (2008-2012), prior to the Zika epidemic in the Western hemisphere (2015). The associations of suspected risk factors were compared across four clearly defined case groups.

METHODS

Data from the Texas Birth Defects Registry were used to calculate the prevalence of congenital microcephaly and crude and adjusted prevalence ratios using Poisson regression. Twelve maternal and infant factors were assessed across case groups, which included total (explained + unexplained), explained (e.g., syndromic), unexplained, and severe unexplained microcephaly (head circumference <3^rd percentile).

RESULTS

The birth prevalence for total and total severe microcephaly were 14.7 and 4.8 per 10,000 livebirths, respectively. For explained and unexplained cases, significantly elevated risks were noted for mothers who were older (35+), less educated (≤12 years), diabetic (pre-pregnancy or gestational), or had a preterm delivery. Unlike explained cases, however, mothers who were non-White or smoked had an increased risk for unexplained microcephaly. Furthermore, young maternal age (<20), multiparity, and higher BMI reduced the risk for unexplained microcephaly. For severe unexplained cases, the risk profile was similar to that for all unexplained cases-with the exception of null associations noted for diabetes and birth year.

CONCLUSIONS

We found that risk patterns for microcephaly varied across case groupings. Risk factors included maternal race/ethnicity, age, and smoking during pregnancy. Among severe unexplained cases, notable positive associations were seen among mothers who were non-Hispanic Black or less educated, while inverse associations were noted for obesity.

Maternal report of fever from cold or flu during early pregnancy and the risk for noncardiac birth defects, National Birth Defects Prevention Study, 1997-2011

BACKGROUND

As maternal fever affects approximately 6-8% of early pregnancies, it is important to expand upon previous observations of an association between maternal fever and birth defects.

METHODS

We analyzed data from the National Birth Defects Prevention Study, a multistate, case-control study of major structural birth defects. Telephone interviews were completed by mothers of cases (n = 17,162) and controls (n = 10,127). Using multivariable logistic regression, we assessed the association between maternal self-report of cold or flu with fever and cold or flu without fever during early pregnancy and 30 categories of non-cardiac birth defects.

RESULTS

Maternal report of cold or flu with fever was significantly associated with 8 birth defects (anencephaly, spina bifida, encephalocele, cleft lip with or without cleft palate, colonic atresia/stenosis, bilateral renal agenesis/hypoplasia, limb reduction defects, and gastroschisis) with elevated adjusted odds ratios ranging from 1.2 to 3.7. Maternal report of cold or flu without fever was not associated with any of the birth defects studied.

CONCLUSIONS

This study adds to the evidence that maternal fever during early pregnancy is associated with an increased risk for selected birth defects. Elevated associations were limited to mothers who reported a fever, suggesting that it is fever that contributes to the excess risk rather than illnesses associated with it. However, fever may also serve as a marker for more severe infections.

Original Findings and Updated Meta-Analysis for the Association Between Maternal Diabetes and Risk for Congenital Heart Disease Phenotypes

Maternal diabetes is associated with congenital heart defects (CHDs) as a group, but few studies have assessed risk for specific CHD phenotypes. We analyzed these relationships using data from the Texas Birth Defects Registry and statewide vital records for deliveries taking place in 1999-2009 (n = 48,249 cases). We used Poisson regression to calculate prevalence ratios for the associations between maternal diabetes (pregestational or gestational) and each CHD phenotype, adjusting for potential confounders. Analyses were repeated by type of diabetes. To address the potential for misclassification bias, we performed logistic regression, using malformed controls. We also conducted meta-analyses, combining our estimates of the association between pregestational diabetes and each CHD phenotype with previous estimates. The prevalence of every CHD phenotype was greater among women with pregestational diabetes than among nondiabetic women. Most of these differences were statistically significant (adjusted prevalence ratios = 2.47-13.20). Associations were slightly attenuated for many CHD phenotypes among women with gestational diabetes. The observed associations did not appear to be the result of misclassification bias. In our meta-analysis, pregestational diabetes was significantly associated with each CHD phenotype. These findings contribute to a better understanding of the teratogenic effects of maternal diabetes and improved counseling for risk of specific CHD phenotypes.

Role of maternal occupational physical activity and psychosocial stressors on adverse birth outcomes

OBJECTIVES

We examined the association of an array of estimated maternal occupational physical activities and psychosocial stressors during pregnancy with odds for preterm birth (PTB) and small-for-gestational age (SGA).

METHODS

Data for infants born without major birth defects delivered from 1997 to 2009 whose mothers reported working at least 1 month during pregnancy were obtained from the National Birth Defects Prevention Study. We linked occupational codes to the US Department of Labor's Occupational Information Network, which provides estimates of exposure for multiple domains of physical activity and psychosocial stressors by occupational categories. We conducted factor analysis using principal components extraction with 17 occupational activities and calculated factor scores. ORs for PTB and SGA across quartiles of factor scores in each trimester were computed using logistic regression.

RESULTS

Factor analysis grouped occupational domains into 4 groups based on factor loadings. These groups were 'occupational physical activity', 'interpersonal stressor', 'automated work' and 'job responsibility'. High levels of 'occupational physical activity' were significantly associated with SGA (adjusted OR (AOR) for highest quartile compared with lowest quartile of factor score: 1.36; 95% CIs 1.02 to 1.82; p for trend=0.001) and were also positively associated with PTB (AOR: 1.24; 95% CI 0.93 to 1.64; p for trend=0.01). No clear results were observed across domains of psychosocial stressors.

CONCLUSIONS

Our findings expand understanding of associations between occupational physical activity and psychosocial stressors and PTB and SGA and suggest that additional research is needed to further examine these relationships.

Maternal exposure to ozone and PM2.5 and the prevalence of orofacial clefts in four U.S. states

BACKGROUND

While there is some evidence that maternal exposure to ambient air pollution is associated with orofacial clefts in offspring, the epidemiologic studies have been largely equivocal. We evaluated whether maternal exposure to elevated county-level ambient fine particulate matter with aerodynamic diameter ≤2.5µm (PM_2.5) and ozone during early gestation was associated with a higher prevalence of orofacial clefts.

METHODS

Birth data consisting of 4.7 million births from 2001 to 2007 were obtained from National Birth Defects Prevention Network for four states - Arizona, Florida, New York (excluding New York City), and Texas. The air pollution exposure assessment for gestational weeks 5-10 was based on county-level average concentrations of PM_2.5 and ozone data generated using a Bayesian fusion model available through CDC's Environmental Public Health Tracking Network. Two outcomes were analyzed separately: cleft lip with or without cleft palate, cleft palate alone. In logistic regression analyses, we adjusted for factors that were suspected confounders or modifiers of the association between the prevalence of orofacial clefts and air pollution, i.e., infant sex, race-ethnicity, maternal education, smoking status during pregnancy, whether this was mother's first baby, maternal age.

RESULTS

Each 10µg/m³ increase in PM_2.5 concentration was significantly associated with cleft palate alone (OR =1.43, 95% CI: 1.11-1.86). There was no significant association between PM_2.5 concentration and cleft lip with or without cleft palate. No associations were observed between ozone exposure and the two outcomes of orofacial clefts.

CONCLUSIONS

Our study suggests that PM_2.5 significantly increased the risk of cleft palate alone, but did not change the incidence of cleft lip with or without palate. Ozone levels did not correlate with incidence of orofacial clefts.

A population-based analysis of mortality in patients with Turner syndrome and hypoplastic left heart syndrome using the Texas Birth Defects Registry

BACKGROUND

Hypoplastic left heart syndrome (HLHS) is strongly associated with Turner syndrome (TS); outcome data when these conditions coexist is sparse. We aimed to investigate long-term survival and causes of death in this population.

METHODS

The Texas Birth Defects Registry was queried for all live born infants with HLHS during 1999-2007. We used Kaplan-Meier and Cox regression analyses to compare survival among patients with HLHS with TS (HLHS/TS+) to patients who had HLHS without genetic disorders or extracardiac birth defects (HLHS/TS-).

RESULTS

Of the 542 patients with HLHS, 11 had TS (2.0%), 71 had other extracardiac birth defects or genetic disorders, and 463 had neither. The median follow-up time was 4.2 y (interquartile range [IQR] 2.1-6.5). Comparing those with HLHS/TS+ to HLHS/TS-, 100% versus 35% were female (P < .001), and median birth weight was 2140 g (IQR 1809-2650) versus 3196 g (IQR 2807-3540, P < .001). Neonatal mortality was 36% in HLHS/TS+ versus 27% in HLHS/TS- (log rank = 0.431). Ten of the 11 TS+ patients died during the study period for cumulative mortality of 91% versus 50% (hazard ratio (HR) for TS+: 2.90, 95% CI 1.53-5.48). Six patients died prior to surgery, 5 underwent Stage 1 palliation (S1P), 3 died after S1P, 2 survived past S2P, and one of these died at age 19 mo. The underlying cause of death was listed as congenital heart disease on all the death certificates of HLHS/TS+ patients. In multivariable analysis controlling for low birth weight (<2500 g), TS remained associated with significantly increased cumulative mortality, although females without TS had higher mortality than males (HR for TS+ versus males: 2.42, 95% CI 1.24-4.73; HR for TS- females versus males: 1.41, 95% CI 1.08-1.83).

CONCLUSION

TS with HLHS is associated with significant mortality. The increased mortality in females without documented TS calls to question if TS is undetected in a portion of females with HLHS.

Maternal hypertension and risk for hypospadias in offspring

Hypospadias is one of the most common birth defects in male infants. Maternal hypertension is a suspected risk factor; however, few previous studies have addressed the possibility of reporting bias, and several previous studies have not accounted for hypospadias severity. We analyzed data from the Texas Birth Defects Registry for 10,924 nonsyndromic cases and statewide vital records for deliveries during 1999-2009, using Poisson regression. After adjustment for potential confounders, hypospadias was associated with maternal hypertension (adjusted prevalence ratio: 1.5, 95% confidence interval: 1.4-1.7). Similar associations were observed with gestational and pregestational hypertension, including separate analyses restricted to the subset of cases with severe (second- or third-degree) hypospadias. All of these associations were also similar among the subset of cases with isolated hypospadias (without additional birth defects). To evaluate the potential for bias due to potential hypertension misclassification, we repeated our analyses using logistic regression, comparing the cases to controls with other birth defects. In these analyses, the associations with gestational hypertension were similar, but adjusted associations with pregestational hypertension were no longer observed. Our findings support an association between gestational hypertension and hypospadias in offspring, but also suggest that previously observed associations with pregestational hypertension may have been inflated due to differential misclassification of hypertension (e.g., reporting bias). As gestational hypertension is recognized after hypospadias development, more research is needed to determine if this association reflects an increase in gestational hypertension risk secondary to hypospadias or if both conditions have shared risk factors (e.g., precursors of gestational hypertension). © 2016 Wiley Periodicals, Inc.

Prenatal diagnosis, hospital characteristics, and mortality in transposition of the great arteries

BACKGROUND

The role of prenatal diagnosis in reducing neonatal mortality from transposition of the great arteries (TGA) is controversial. Factors affected by prenatal diagnosis such as proximity at birth to a cardiac surgical center (CSC) and CSC volume are associated with mortality in congenital heart disease. The purpose of the study was to determine the associations between prenatal diagnosis, distance from birthplace to a CSC, CSC TGA volume, and neonatal mortality in patients with TGA.

METHODS

The Texas Birth Defects Registry was queried for all live born infants with TGA from 1999 to 2007. Four hundred sixty-eight cases of TGA were included.

RESULTS

Forty-eight patients (10.3%) were prenatally diagnosed, and 20 patients died before age 28 days (4.3%). Neither prenatal diagnosis nor close proximity to a CSC at birth (p > 0.05) were associated with decreased mortality. Low CSC TGA volume was associated with increased mortality (p < 0.0002). Mortality at the CSCs with <5 patients per year was 9.6%; CSCs with 5 to 10 patients per year had 0% mortality, and those with >10 patients per year had 2.3% mortality. In multivariable logistic regression, only preterm birth (odds ratio, 7.05; 95% confidence interval, 4.13-12.05) and lower CSC volume (p < 0.001) were associated with neonatal mortality, although prenatal diagnosis attenuated the detrimental association of lower volume CSCs with higher mortality (p for interaction = 0.047).

CONCLUSION

Lower CSC TGA patient volume was associated with higher neonatal mortality. Prenatal diagnosis may improve survival in lower volume CSCs. Birth Defects Research (Part A) 106:739-748, 2016. © 2016 Wiley Periodicals, Inc.

Prenatal Exposure to Nitrosatable Drugs, Dietary Intake of Nitrites, and Preterm Birth

Prenatal exposure to nitrosatable drugs, including secondary or tertiary amines, has been associated with preterm birth. Associations may be accentuated by higher intakes of dietary nitrites because of the increased formation of N-nitroso compounds. Using data from mothers of babies without major birth defects (controls) from the National Birth Defects Prevention Study, we examined the relationship between nitrosatable drug exposure in conjunction with dietary nitrite intake and preterm birth among 496 mothers of preterm infants and 5,398 mothers with full-term deliveries in 1997-2005. A protective association was observed with a high intake of plant nitrites (adjusted hazard ratio (AHR) = 0.72, 95% confidence interval (CI): 0.53, 0.97). Secondary amines in conjunction with high nitrite intake were associated with preterm birth during the first (AHR = 1.84, 95% CI: 1.14, 2.98), second (AHR = 1.89, 95% CI: 1.17, 3.07), and third (AHR = 2.00, 95% CI: 1.22, 3.29) trimesters. The adjusted hazard ratios for tertiary amine use in the third trimester by increasing tertiles of nitrite intake were 0.67 (95% CI: 0.35, 1.31), 1.25 (95% CI: 0.71, 2.19), and 2.02 (95% CI: 1.17, 3.49). Prenatal exposure to nitrosatable drugs, particularly secondary and tertiary amines, in conjunction with higher levels of dietary nitrite intake may increase the risk of preterm birth.

Data linkage between the National Birth Defects Prevention Study and the Occupational Information Network (O*NET) to assess workplace physical activity, sedentary behaviors, and emotional stressors during pregnancy

BACKGROUND

Knowledge of the prevalence of work-related physical activities, sedentary behaviors, and emotional stressors among pregnant women is limited, and the extent to which these exposures vary by maternal characteristics remains unclear.

METHODS

Data on mothers of 6,817 infants without major birth defects, with estimated delivery during 1997 through 2009 who worked during pregnancy were obtained from the National Birth Defects Prevention Study. Information on multiple domains of occupational exposures was gathered by linking mother's primary job to the Occupational Information Network Version 9.0.

RESULTS

The most frequent estimated physical activity associated with jobs during pregnancy was standing. Of 6,337 mothers, 31.0% reported jobs associated with standing for ≥75% of their time. There was significant variability in estimated occupational exposures by maternal age, race/ethnicity, and educational level.

CONCLUSIONS

Our findings augment existing literature on occupational physical activities, sedentary behaviors, emotional stressors, and occupational health disparities during pregnancy.

Survival of children with trisomy 13 and trisomy 18: A multi-state population-based study

Trisomy 13 (T13) and trisomy 18 (T18) are among the most prevalent autosomal trisomies. Both are associated with a very high risk of mortality. Numerous instances, however, of long-term survival of children with T13 or T18 have prompted some clinicians to pursue aggressive treatment instead of the traditional approach of palliative care. The purpose of this study is to assess current mortality data for these conditions. This multi-state, population-based study examined data obtained from birth defect surveillance programs in nine states on live-born infants delivered during 1999-2007 with T13 or T18. Information on children's vital status and selected maternal and infant risk factors were obtained using matched birth and death certificates and other data sources. The Kaplan-Meier method and Cox proportional hazards models were used to estimate age-specific survival probabilities and predictors of survival up to age five. There were 693 children with T13 and 1,113 children with T18 identified from the participating states. Among children with T13, 5-year survival was 9.7%; among children with T18, it was 12.3%. For both trisomies, gestational age was the strongest predictor of mortality. Females and children of non-Hispanic black mothers had the lowest mortality. Omphalocele and congenital heart defects were associated with an increased risk of death for children with T18 but not T13. This study found survival among children with T13 and T18 to be somewhat higher than those previously reported in the literature, consistent with recent studies reporting improved survival following more aggressive medical intervention for these children. © 2015 Wiley Periodicals, Inc.

Maltreatment of Children Under Age 2 With Specific Birth Defects: A Population-Based Study

BACKGROUND AND OBJECTIVES

Children with disabilities are at an increased risk for maltreatment. However, the risk of maltreatment is unknown for children with specific types of birth defects. This study was conducted to determine whether the risk and predictors of maltreatment differ between children with and without 3 birth defects: Down syndrome, cleft lip with/without cleft palate, and spina bifida.

METHODS

This population-based study of substantiated childhood maltreatment was conducted in Texas from 2002 to 2011. Linked data were used to describe the risk and types of maltreatment that occurred before age 2 years in children with and without specific birth defects. Poisson regression was used to identify predictors of maltreatment and assess differences in those predictors between children with and without these specific birth defects.

RESULTS

The risk of maltreatment (any type) in children with cleft lip with/without cleft palate and spina bifida was increased by 40% and 58%, respectively, compared with children with no birth defects. The risk of any maltreatment was similar between children with Down syndrome and unaffected children. Across birth defect groups, the risk of medical neglect was 3 to 6 times higher than in the unaffected group. Child-, family-, and neighborhood-level factors predicted maltreatment in children with and without birth defects.

CONCLUSIONS

The overall risk of substantiated maltreatment was significantly higher for some but not all birth defect groups. The factors associated with increased risk were similar across groups. Enhancement of existing maltreatment prevention and early intervention programs may be effective mechanisms to provide at-risk families additional support.

Development and implementation of the first national data quality standards for population-based birth defects surveillance programs in the United States

Background

Population-based birth defects surveillance is a core public health activity in the United States (U.S.); however, the lack of national data quality standards has limited the use of birth defects surveillance data across state programs. Development of national standards will facilitate data aggregation and utilization across birth defects surveillance programs in the U.S.

Methods

Based on national standards for other U.S. public health surveillance programs, existing National Birth Defects Prevention Network (NBDPN) guidelines for conducting birth defects surveillance, and information from birth defects surveillance programs regarding their current data quality practices, we developed 11 data quality measures that focused on data completeness (n = 5 measures), timeliness (n = 2), and accuracy (n = 4). For each measure, we established tri-level performance criteria (1 = rudimentary, 2 = essential, 3 = optimal). In January 2014, we sent birth defects surveillance programs in each state, District of Columbia, Puerto Rico, Centers for Disease Control and Prevention (CDC), and the U.S. Department of Defense Birth and Infant Health Registry an invitation to complete a self-administered NBDPN Standards Data Quality Assessment Tool. The completed forms were electronically submitted to the CDC for analyses.

Results

Of 47 eligible population-based surveillance programs, 45 submitted a completed assessment tool. Two of the 45 programs did not meet minimum inclusion criteria and were excluded; thus, the final analysis included information from 43 programs. Average scores for four of the five completeness performance measures were above level 2. Conversely, the average scores for both timeliness measures and three of the four accuracy measures were below level 2. Surveillance programs using an active case-finding approach scored higher than programs using passive case-finding approaches for the completeness and accuracy measures, whereas their average scores were lower for timeliness measures.

Conclusions

This initial, nation-wide assessment of data quality across U.S. population-based birth defects surveillance programs highlights areas for improvement. Using this information to identify strengths and weaknesses, the birth defects surveillance community, working through the NBDPN, can enhance and implement a consistent set of standards that can promote uniformity and enable surveillance programs to work towards improving the potential of these programs.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-015-2223-2) contains supplementary material, which is available to authorized users.

Racial disparities in heterotaxy syndrome

BACKGROUND

Heterotaxy syndrome (HTX) is a constellation of defects including abnormal organ lateralization and often including congenital heart defects. HTX has widely divergent population-based estimates of prevalence, racial and ethnic predominance, and mortality in current literature.

METHODS

The objective of this study was to use a population-based registry to investigate potential racial and ethnic disparities in HTX. Using the Texas Birth Defects Registry, we described clinical features and mortality of HTX among infants delivered from 1999 to 2006. We calculated birth prevalence and crude prevalence (cPR) ratios for infant sex, maternal diabetes, and sociodemographic factors.

RESULTS

A total of 353 HTX cases were identified from 2,993,604 births (prevalence ratio = 1.18 per 10,000 live births. HTX prevalence was approximately 70% higher among infants of Hispanic and non-Hispanic black mothers and 28% higher among female infants (cPR = 1.28; 95% confidence interval,1.04-1.59). There was a twofold higher female preponderance for infants of mothers who were non-Hispanic white or black. Mothers with diabetes were three times more likely to have a child with HTX compared with nondiabetics (cPR = 3.13; 95% confidence interval, 2.12-4.45). Among nondiabetics, HTX cases were 86% more likely to have a Hispanic mother and 72% a non-Hispanic black mother. First-year mortality for live born children with HTX was 30.9%.

CONCLUSION

This study represents one of the largest population-based studies of HTX to date, with a novel finding of higher rates of HTX among Hispanic infants of mostly Mexican origin, as well as among female infants of only non-Hispanic white and black mothers. These findings warrant further investigation.

Periconceptional Risk Factors for Birth Defects among Younger and Older Teen Mothers

STUDY OBJECTIVES

We sought to determine whether selected periconceptional health behaviors that influence risk for birth defects differ between older and younger adolescents and whether pregnancy intention predicts more positive preconception health behaviors among teens.

DESIGN AND PARTICIPANTS

We analyzed interview responses from 954 adolescent control group participants from the National Birth Defects Prevention Study who delivered live infants during 1997-2007.

MAIN OUTCOME MEASURES

Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were calculated for factors of interest by age categories (13-15, 16-17, and 18 years, relative to 19 years). To construct a composite periconceptional behavior index, we summed the following healthy behaviors: nonsmoker, nondrinker, folic acid supplementation, and eating 5 or more servings of fruits and vegetables per day.

RESULTS

Analyses indicated that women in the youngest group (13-15 years of age) were more likely to be Hispanic (aOR 2.83, 95% CI 1.40-5.70) and less likely to engage in some unhealthy pregnancy-related behaviors compared with 19-year-olds, such as smoking (aOR 0.45, 95% CI 0.20-0.99) and being overweight or obese (aOR 0.32, 95% CI 0.16-0.61). However, they were also less likely to have taken periconceptional folic acid (aOR 0.44, 95% CI 0.21-0.90). About one-third of teen mothers indicated that their pregnancies had been intended. Among 18- and 19-year-olds, this predicted a higher mean value for the composite periconceptional behavior index (2.30 versus 1.94, P ≤ .01).

CONCLUSIONS

Teen mothers are not a homogeneous group. Each age subgroup presents varied demographic and behavioral factors that put them at varying levels of risk for birth defects. Furthermore, caregivers should not assume that teens do not plan pregnancies or that they need not be informed of the importance of periconceptional health.

Maternal exposures in the National Birth Defects Prevention Study: Time trends of selected exposures

BACKGROUND

Our objective was to describe time trends in selected pregnancy exposures in the National Birth Defects Prevention Study (NBDPS).

METHODS

We analyzed data from the NBDPS, a multi-site case-control study of major birth defects, for mothers of live-born infants without birth defects (controls), with an expected date of delivery (EDD) from 1998 to 2011. Mothers from the 10 participating centers across the United States were interviewed by phone between 6 weeks and 2 years after the EDD. We focused on maternal race/ethnicity and five maternal risk factors: obesity, use of folic acid-containing multivitamins, opioid analgesics, selective serotonin reuptake inhibitors, and loratadine because of their prevalence of use and some reports of associations with major birth defects. Prevalence time trends were examined using the Kendall's τβ test statistic.

RESULTS

The exposure trend analysis included 11,724 control mothers with EDDs from 1998 to 2011. We observed a significant increase in obesity prevalence among control mothers, as well as use of selective serotonin reuptake inhibitors and loratadine. We also observed an increase in periconceptional use of folic acid-containing multivitamins. Some of the time trends varied by race/ethnicity. No remarkable trend in the overall use of opioid analgesics was observed. The racial/ethnic distribution of mothers changed slightly during the study period.

CONCLUSION

Long-term, population-based case-control studies continue to be an effective way to assess exposure-birth defects associations and provide guidance to health care providers. However, investigators examining rare outcomes covering many years of data collection need to be cognizant of time trends in exposures.

Racial/ethnic differences in survival of United States children with birth defects: a population-based study

OBJECTIVES

To examine racial/ethnic-specific survival of children with major birth defects in the US.

STUDY DESIGN

We pooled data on live births delivered during 1999-2007 with any of 21 birth defects from 12 population-based birth defects surveillance programs. We used the Kaplan-Meier method to calculate cumulative survival probabilities and Cox proportional hazards models to estimate mortality risk.

RESULTS

For most birth defects, there were small-to-moderate differences in neonatal (<28 days) survival among racial/ethnic groups. However, compared with children born to non-Hispanic white mothers, postneonatal infant (28 days to <1 year) mortality risk was significantly greater among children born to non-Hispanic black mothers for 13 of 21 defects (hazard ratios [HRs] 1.3-2.8) and among children born to Hispanic mothers for 10 of 21 defects (HRs 1.3-1.7). Compared with children born to non-Hispanic white mothers, a significantly increased childhood (≤ 8 years) mortality risk was found among children born to Asian/Pacific Islander mothers for encephalocele (HR 2.6), tetralogy of Fallot, and atrioventricular septal defect (HRs 1.6-1.8) and among children born to American Indian/Alaska Native mothers for encephalocele (HR 2.8), whereas a significantly decreased childhood mortality risk was found among children born to Asian/Pacific Islander mothers for cleft lip with or without cleft palate (HR 0.6).

CONCLUSION

Children with birth defects born to non-Hispanic black and Hispanic mothers carry a greater risk of mortality well into childhood, especially children with congenital heart defect. Understanding survival differences among racial/ethnic groups provides important information for policy development and service planning.

Sex ratios among infants with birth defects, National Birth Defects Prevention Study, 1997-2009

A small number of population-based studies have examined sex differences among infants with birth defects. This study presents estimates of sex ratio for both isolated cases and those with multiple congenital anomalies, as well as by race/ethnicity. Male-female sex ratios and their 95% confidence intervals were calculated for 25,952 clinically reviewed case infants included in the National Birth Defects Prevention Study (1997-2009), a large population-based case-control study of birth defects. The highest elevations in sex ratios (i.e., male preponderance) among isolated non-cardiac defects were for craniosynostosis (2.12), cleft lip with cleft palate (2.01), and cleft lip without cleft palate (1.78); the lowest sex ratios (female preponderance) were for choanal atresia (0.45), cloacal exstrophy (0.46), and holoprosencephaly (0.64). Among isolated cardiac defects, the highest sex ratios were for aortic stenosis (2.88), coarctation of the aorta (2.51), and d-transposition of the great arteries (2.34); the lowest were multiple ventricular septal defects (0.52), truncus arteriosus (0.63), and heterotaxia with congenital heart defect (0.64). Differences were observed by race/ethnicity for some but not for most types of birth defects. The sex differences we observed for specific defects, between those with isolated versus multiple defects, as well as by race/ethnicity, demonstrate patterns that may suggest etiology and improve classification.

Nitrosatable Drug Exposure during Pregnancy and Preterm and Small-for-Gestational-Age Births

BACKGROUND

Nitrosatable drugs react with nitrite in the stomach to form N-nitroso compounds, observed in animal models to result in adverse pregnancy outcomes, such as birth defects and reduced fetal weight. Previous studies examining prenatal exposure to medications classified as nitrosatable have reported an increased risk of preterm births (PTBs) and small-for-gestational-age (SGA) infants.

METHODS

Using data from mothers (controls) of babies without major birth defects from the National Birth Defects Prevention Study, prenatal nitrosatable drug usage by trimester and month of gestation was examined in relation to PTBs and SGA infants.

RESULTS

Positive associations were observed with nitrosatable drug use and PTBs, with the strongest relationship with second trimester exposure (adjusted hazard ratio [aHR] 1.37, [95% confidence interval (CI) 1.10, 1.70]). Of the nitrosatable functional groups, secondary amines were the most notable, with a higher association among women with second (aHR 1.37, [95% CI 1.05, 1.79]) and third (aHR 1.34, [95% CI 1.02, 1.76]) trimester exposure compared with women with no prenatal nitrosatable drug use. Among SGA infants, a borderline association was noted with amide exposure during the third trimester (adjusted odds ratio 1.43 [95% confidence interval [CI] 1.00, 2.05]).

CONCLUSIONS

Prenatal exposure to nitrosatable drugs during the second and third trimester of pregnancy, particularly secondary amines, might increase the risk of PTBs. However, prenatal exposure to nitrosatable drugs was not associated with SGA infants, with the exception of amide drugs.

Birth defects data from population-based birth defects surveillance programs in the United States, 2007 to 2011: highlighting orofacial clefts

© 2014 The Authors Birth Defects Research Part A: Clinical and Molecular Teratology Published by Wiley Periodicals, Inc.

Maternal residential atrazine exposure and gastroschisis by maternal age

Previous literature has suggested a link between maternal exposure to atrazine (the most commonly used herbicide in the US) and risk for gastroschisis (a birth defect that involves incomplete closure of the abdominal wall). Our objective was to evaluate the relationship between maternal atrazine exposure and gastroschisis risk by maternal age. We analyzed data for 1,161 cases with isolated gastroschisis and 8,390 controls delivered in Texas from 1999 through 2008. We estimated atrazine exposure based on maternal county of residence and data from the United States Geological Survey. Logistic regression was conducted among all subjects, and separately among offspring of women <25 and ≥25 years. Risk for gastroschisis in offspring was significantly increased for women ≥25 years with high levels of residential atrazine exposure compared to low (adjusted odds ratio: 1.97, 95 % confidence interval 1.19-3.26). This association was not observed among women <25 years. Our results provide additional insight into the suspected relationship of gastroschisis with atrazine. This relationship appears to be different in older versus younger mothers, providing further evidence that the etiology of gastroschisis may vary based on maternal age.