Population-based birth defects data in the United States, 2012-2016: A focus on abdominal wall defects.

BACKGROUND/OBJECTIVES: In this report, the National Birth Defects Prevention Network (NBDPN) examines and compares gastroschisis and omphalocele for a recent 5-year birth cohort using data from 30 population-based birth defect surveillance programs in the United States. METHODS: As a special call for data for the 2019 NBDPN Annual Report, state programs reported expanded data on gastroschisis and omphalocele for birth years 2012-2016. We estimated the overall prevalence (per 10,000 live births) and 95% confidence intervals (CI) for each defect as well as by maternal race/ethnicity, maternal age, infant sex, and case ascertainment methodology utilized by the program (active vs. passive). We also compared distribution of cases by maternal and infant factors and presence/absence of other birth defects. RESULTS: The overall prevalence estimates (per 10,000 live births) were 4.3 (95% CI: 4.1-4.4) for gastroschisis and 2.1 (95% CI: 2.0-2.2) for omphalocele. Gastroschisis was more frequent among young mothers (<25 years) and omphalocele more common among older mothers (>40 years). Mothers of infants with gastroschisis were more likely to be underweight/normal weight prior to pregnancy and mothers of infants with omphalocele more likely to be overweight/obese. Omphalocele was twice as likely as gastroschisis to co-occur with other birth defects. CONCLUSIONS: This report highlights important differences between gastroschisis and omphalocele. These differences indicate the importance of distinguishing between these defects in epidemiologic assessments. The report also provides additional data on co-occurrence of gastroschisis and omphalocele with other birth defects. This information can provide a basis for future research to better understand these defects.

Gastroschisis Trends and Ecologic Link to Opioid Prescription Rates - United States, 2006-2015.

Prevalence of gastroschisis, a serious birth defect of the abdominal wall resulting in some of the abdominal contents extending outside the body at birth, has been increasing worldwide (1,2). Gastroschisis requires surgical repair after birth and is associated with digestive and feeding complications during infancy, which can affect development. Recent data from 14 U.S. states indicated an increasing prevalence of gastroschisis from 1995 to 2012 (1). Young maternal age has been strongly associated with gastroschisis, but research suggests that risk factors such as smoking, genitourinary infections, and prescription opioid use also might be associated (3-5). Data from 20 population-based state surveillance programs were pooled and analyzed to assess age-specific gastroschisis prevalence during two 5-year periods, 2006-2010 and 2011-2015, and an ecologic approach was used to compare annual gastroschisis prevalence by annual opioid prescription rate categories. Gastroschisis prevalence increased only slightly (10%) from 2006-2010 to 2011-2015 (prevalence ratio = 1.1, 95% confidence interval [CI] = 1.0-1.1), with the highest prevalence among mothers aged <20 years. During 2006-2015, the prevalence of gastroschisis was 1.6 times higher in counties with high opioid prescription rates (5.1 per 10,000 live births; CI = 4.9-5.3) and 1.4 times higher where opioid prescription rates were medium (4.6 per 10,000 live births; CI = 4.4-4.8) compared with areas with low prescription rates (3.2 per 10,000 live births; CI = 3.1-3.4). Public health research is needed to understand factors contributing to the association between young maternal age and gastroschisis and assess the effect of prescription opioid use during pregnancy on this pregnancy outcome.

Recognition of clinical characteristics for population-based surveillance of fetal alcohol syndrome.

BACKGROUND: The diagnosis of fetal alcohol syndrome (FAS) rests on identification of characteristic facial, growth, and central nervous system (CNS) features. Public health surveillance of FAS depends on documentation of these characteristics. We evaluated if reporting of FAS characteristics is associated with the type of provider examining the child. METHODS: We analyzed cases aged 7-9 years from the Fetal Alcohol Syndrome Surveillance Network II (FASSNetII). We included cases whose surveillance records included the type of provider (qualifying provider: developmental pediatrician, geneticist, neonatologist; other physician; or other provider) who evaluated the child as well as the FAS diagnostic characteristics (facial dysmorphology, CNS impairment, and/or growth deficiency) reported by the provider. RESULTS: A total of 345 cases were eligible for this analysis. Of these, 188 (54.5%) had adequate information on type of provider. Qualifying physicians averaged more than six reported FAS characteristics while other providers averaged less than five. Qualifying physicians reported on facial characteristics and developmental delay more frequently than other providers. Also, qualifying physicians reported on all three domains of characteristics (facial, CNS, and growth) in 97% of cases while others reported all three characteristics on two thirds of cases. CONCLUSIONS: Documentation in medical records during clinical evaluations for FAS is lower than optimal for cross-provider communication and surveillance purposes. Lack of documentation limits the quality and quantity of information in records that serve as a major source of data for public health surveillance systems.

Use of Mixed CH3-/HC(O)CH2CH2-Si(111) Functionality to Control Interfacial Chemical and Electronic Properties During the Atomic-Layer Deposition of Ultrathin Oxides on Si(111).

Silicon surfaces terminated with a mixed monolayer containing both a propyl aldehyde functionality and methyl groups were prepared and used to control the interfacial chemical and electronic properties of Si(111) surfaces during atomic-layer deposition (ALD) of Al2O3 or MnO. Si(111) surfaces functionalized only with the aldehyde moiety exhibited surface recombination velocities, S, of 2500 ± 600 cm s(-1) whereas the mixed CH3-/HC(O)CH2CH2-Si(111) surfaces displayed S = 25 ± 7 cm s(-1). During the ALD growth of either Al2O3 or MnO, both the HC(O)CH2CH2-Si(111) and CH3-/HC(O)CH2CH2-Si(111) surfaces produced increased metal oxide deposition at low cycle number, relative to H-Si(111) or CH3-Si(111) surfaces. As detected by X-ray photoelectron spectroscopy after the ALD process, the CH3- and mixed CH3-/HC(O)CH2CH2- functionalized Si(111) surfaces exhibited less interfacial SiOx than was observed for ALD of metal oxides on H-Si(111) substrates.

Methods for surveillance of fetal alcohol syndrome: The Fetal Alcohol Syndrome Surveillance Network II (FASSNetII) - Arizona, Colorado, New York, 2009 - 2014.

Surveillance of fetal alcohol syndrome (FAS) is important for monitoring the effects of prenatal alcohol exposure and describing the public health burden of this preventable disorder. Building on the infrastructure of the Fetal Alcohol Syndrome Surveillance Network (FASSNet, 1997-2002), in 2009 the Centers for Disease Control and Prevention awarded 5-year cooperative agreements to three states, Arizona, Colorado, and New York, to conduct population-based surveillance of FAS. The Fetal Alcohol Syndrome Surveillance Network II (FASSNetII, 2009-2014) developed a surveillance case definition based on three clinical criteria: characteristic facial features, central nervous system abnormalities, and growth deficiency. FASSNetII modified the FASSNet methods in three important ways: (1) estimation of a period prevalence rather than birth prevalence; (2) surveillance of FAS among school-age children (ages 7-9 years) to better document the central nervous system abnormalities that are not apparent at birth or during infancy; and (3) implementation of an expert clinical review of abstracted data for probable and confirmed cases classified through a computerized algorithm. FASSNetII abstracted data from multiple sources including birth records, medical records from child development centers or other specialty clinics, and administrative databases such as hospital discharge and Medicaid. One challenge of FASSNetII was its limited access to non-medical records. The FAS prevalence that could be estimated was that of the population identified through an encounter with the healthcare system. Clinical and public health programs that identify children affected by FAS provide critical information for targeting preventive, medical and educational services in this vulnerable population.

Fetal alcohol syndrome among children aged 7-9 years - Arizona, Colorado, and New York, 2010.

Fetal alcohol syndrome (FAS) is a serious birth defect and developmental disorder caused by in utero exposure to alcohol. Assessment of the public health burden of FAS through surveillance has proven difficult; there is wide variation in reported prevalence depending on the study population and surveillance method. Generally, records-based birth prevalence studies report estimates of 0.2-1.5 per 1,000 live births, whereas studies that use in-person, expert assessment of school-aged children in a community report estimates of 6-9 per 1,000 population. The Fetal Alcohol Syndrome Surveillance Network II addressed some of the challenges in records-based ascertainment by assessing a period prevalence of FAS among children aged 7‒9 years in Arizona, Colorado, and New York. The prevalence across sites ranged from 0.3 to 0.8 per 1,000 children. Prevalence of FAS was highest among American Indian/Alaska Native children and lowest among Hispanic children. These estimates continue to be much lower than those obtained from studies using in-person, expert assessment. Factors that might contribute to this discrepancy include 1) inadequate recognition of the physical and behavioral characteristics of FAS by clinical care providers; 2) insufficient documentation of those characteristics in the medical record; and 3) failure to consider prenatal alcohol exposure with diagnoses of behavioral and learning problems. Addressing these factors through training of medical and allied health providers can lead to practice changes, ultimately increasing recognition and documentation of the characteristics of FAS.

The interaction of organic adsorbate vibrations with substrate lattice waves in methyl-Si(111)-(1 × 1).

A combined helium atom scattering and density functional perturbation theory study has been performed to elucidate the surface phonon dispersion relations for both the CH3-Si(111)-(1 × 1) and CD3-Si(111)-(1 × 1) surfaces. The combination of experimental and theoretical methods has allowed characterization of the interactions between the low energy vibrations of the adsorbate and the lattice waves of the underlying substrate, as well as characterization of the interactions between neighboring methyl groups, across the entire wavevector resolved vibrational energy spectrum of each system. The Rayleigh wave was found to hybridize with the surface rocking libration near the surface Brillouin zone edge at both the M̄-point and K̄-point. The calculations indicated that the range of possible energies for the potential barrier to the methyl rotation about the Si-C axis is sufficient to prevent the free rotation of the methyl groups at a room temperature interface. The density functional perturbation theory calculations revealed several other surface phonons that experienced mode-splitting arising from the mutual interaction of adjacent methyl groups. The theory identified a Lucas pair that exists just below the silicon optical bands. For both the CH3- and CD3-terminated Si(111) surfaces, the deformations of the methyl groups were examined and compared to previous experimental and theoretical work on the nature of the surface vibrations. The calculations indicated a splitting of the asymmetric deformation of the methyl group near the zone edges due to steric interactions of adjacent methyl groups. The observed shifts in vibrational energies of the -CD3 groups were consistent with the expected effect of isotopic substitution in this system.

Exploring the feasibility of using electronic health records in the surveillance of fetal alcohol syndrome.

BACKGROUND: Explore the use of electronic health records (EHRs) in fetal alcohol syndrome (FAS) surveillance systems. METHODS: Using EHRs we identified diagnoses and anthropometric measurements related to the FAS criteria developed by the Fetal Alcohol Syndrome Surveillance Network (FASSNet) among children aged 0 to 12 years. RESULTS: There were 143,393 distinct children aged between 0 and 12 years enrolled in Kaiser Permanente, Georgia, during the study period. Based on diagnoses and anthropometric measurements, 20,101 children met at least one criterion of interest, and when grouped into combinations of different criteria there were 2285 who met GROWTH+CNS criteria, 76 children who met GROWTH+FACE criteria, 107 children who met CNS+FACE criteria, and 93 children who met GROWTH+CNS+FACE criteria. The prevalence of FAS as defined by FASSNet is 1.92 per 1000 children. We linked 17,084 (85.0%) children to their mothers in the health plan; only 3% of mothers of children in the GROWTH+CNS+FACE group had an indication of alcohol or drugs use, but they had the highest rate of depression (39%). CONCLUSION: Data of utility in identification of FAS are readily available in EHRs and may serve as a basis for intervention with at-risk children and in planning of future FAS surveillance programs.

Heck coupling of olefins to mixed methyl/thienyl monolayers on Si(111) surfaces.

The Heck reaction has been used to couple olefins to a Si(111) surface that was functionalized with a mixed monolayer comprised of methyl and thienyl groups. The coupling method maintained a conjugated linkage between the surface and the olefinic surface functionality, to allow for facile charge transfer from the silicon surface. While a Si(111) surface terminated only with thienyl groups displayed a surface recombination velocity, S, of 670 ± 190 cm s(-1), the mixed CH3/SC4H3-Si(111) surfaces with a coverage of θSC4H3 = 0.15 ± 0.02 displayed a substantially lower value of S = 27 ± 9 cm s(-1). Accordingly, CH3/SC4H3-Si(111) surfaces were brominated with N-bromosuccinimide, to produce mixed CH3/SC4H2Br-Si(111) surfaces with coverages of θBr-Si < 0.05. The resulting aryl halide surfaces were activated using [Pd(PPh3)4] as a catalyst. After activation, Pd(II) was selectively coordinated by oxidative addition to the surface-bound aryl halide. The olefinic substrates 4-fluorostyrene, vinylferrocene, and protoporphyrin IX dimethyl ester were then coupled (in dimethylformamide at 100 °C) to the Pd-containing functionalized Si surfaces. The porphyrin-modified surface was then metalated with Co, Cu, or Zn. The vinylferrocene-modified Si(111) surface showed a linear dependence of the peak current on scan rate in cyclic voltammetry, indicating that facile electron transfer had been maintained and providing evidence of a robust linkage between the Si surface and the tethered ferrocene. The final Heck-coupled surface exhibited S = 70 cm s(-1), indicating that high-quality surfaces could be produced by this multistep synthetic approach for tethering small molecules to silicon photoelectrodes.

The association of low socioeconomic status and the risk of having a child with Down syndrome: a report from the National Down Syndrome Project.

PURPOSE: Advanced maternal age and altered recombination are known risk factors for Down syndrome cases due to maternal nondisjunction of chromosome 21, whereas the impact of other environmental and genetic factors is unclear. The aim of this study was to investigate an association between low maternal socioeconomic status and chromosome 21 nondisjunction. METHODS: Data from 714 case and 977 control families were used to assess chromosome 21 meiosis I and meiosis II nondisjunction errors in the presence of three low socioeconomic status factors: (i) both parents had not completed high school, (ii) both maternal grandparents had not completed high school, and (iii) an annual household income of <$25,000. We applied logistic regression models and adjusted for covariates, including maternal age and race/ethnicity. RESULTS: As compared with mothers of controls (n = 977), mothers with meiosis II chromosome 21 nondisjunction (n = 182) were more likely to have a history of one low socioeconomic status factor (odds ratio = 1.81; 95% confidence interval = 1.07-3.05) and ≥2 low socioeconomic status factors (odds ratio = 2.17; 95% confidence interval = 1.02-4.63). This association was driven primarily by having a low household income (odds ratio = 1.79; 95% confidence interval = 1.14-2.73). The same statistically significant association was not detected among maternal meiosis I errors (odds ratio = 1.31; 95% confidence interval = 0.81-2.10), in spite of having a larger sample size (n = 532). CONCLUSION: We detected a significant association between low maternal socioeconomic status and meiosis II chromosome 21 nondisjunction. Further studies are warranted to explore which aspects of low maternal socioeconomic status, such as environmental exposures or poor nutrition, may account for these results.

Preconception folic acid supplementation and risk for chromosome 21 nondisjunction: a report from the National Down Syndrome Project.

Both a lack of maternal folic acid supplementation and the presence of genetic variants that reduce enzyme activity in folate pathway genes have been linked to meiotic nondisjunction of chromosome 21; however, the findings in this area of research have been inconsistent. To better understand these inconsistencies, we asked whether maternal use of a folic acid-containing supplement before conception reduces risk for chromosome 21 nondisjunction. Using questionnaire data from the National Down Syndrome Project, a population-based case-control study, we compared the use of folic acid-containing supplements among mothers of infants with full trisomy 21 due to maternal nondisjunction (n = 702) and mothers of infants born with no major birth defects (n = 983). Using logistic regression, adjusting for maternal age, race/ethnicity, and infant age at maternal interview, we found no evidence of an association between lack of folic acid supplementation and maternal nondisjunction among all case mothers (OR = 1.16; 95% CI: 0.90-1.48). In analyses stratified by meiotic stage and maternal age (<35 or ≥35 years), we found an association among older mothers experiencing meiosis II nondisjunction errors (OR = 2.00; 95% CI: 1.08-3.71). These data suggest that lack of folic acid supplementation may be associated specifically with MII errors in the aging oocyte. If confirmed, these results could account for inconsistencies among previous studies, as each study sample may vary by maternal age structure and proportion of meiotic errors.

Hybridization of surface waves with organic adlayer librations: a helium atom scattering and density functional perturbation theory study of methyl-Si(111).

The interplay of the librations of a covalently bound organic adlayer with the lattice waves of an underlying semiconductor surface was characterized using helium atom scattering in conjunction with analysis by density functional perturbation theory. The Rayleigh wave dispersion relation of CH3- and CD3-terminated Si(111) surfaces was probed across the entire surface Brillouin zone by the use of inelastic helium atom time-of-flight experiments. The experimentally determined Rayleigh wave dispersion relations were in agreement with those predicted by density functional perturbation theory. The Rayleigh wave for the CH3- and CD3-terminated Si(111) surfaces exhibited a nonsinusoidal line shape, which can be attributed to the hybridization of overlayer librations with the vibrations of the underlying substrate. This combined synthetic, experimental, and theoretical effort clearly demonstrates the impact of hybridization between librations of the overlayer and the substrate lattice waves in determining the overall vibrational band structure of this complex interface.

In situ nanomechanical measurements of interfacial strength in membrane-embedded chemically functionalized Si microwires for flexible solar cells.

Arrays of vertically aligned Si microwires embedded in polydimethylsiloxane (PDMS) have emerged as a promising candidate for use in solar energy conversion devices. Such structures are lightweight and concurrently demonstrate competitive efficiency and mechanical flexibility. To ensure reliable functioning under bending and flexing, strong interfacial adhesion between the nanowire and the matrix is needed. In situ uniaxial tensile tests of individual, chemically functionalized, Si microwires embedded in a compliant PDMS matrix reveal that chemical functionality on Si microwire surfaces is directly correlated with interfacial adhesion strength. Chemical functionalization can therefore serve as an effective methodology for accessing a wide range of interfacial adhesion between the rigid constituents and the soft polymer matrix; the adhesion can be quantified by measuring the mechanical strength of such systems.

Characteristics and behaviors of mothers who have a child with fetal alcohol syndrome.

Fetal alcohol syndrome (FAS) is a leading cause of birth defects and developmental disabilities. The objective of this study was to identify the characteristics and behaviors of mothers of children with FAS in the United States using population-based data from the FAS Surveillance Network (FASSNet). FASSNet used a multiple source methodology that identified FAS cases through passive reporting and active review of records from hospitals, specialty clinics, private physicians, early intervention programs, Medicaid, birth certificates and other vital records, birth defects surveillance programs, and hospital discharge data. The surveillance included children born during January 1, 1995-December 31, 1997. In the four states included in our analysis - Arizona, New York, Alaska, and Colorado - there were 257 confirmed cases and 96 probable cases for a total of 353 FAS cases. Compared to all mothers in the states where surveillance occurred, mothers of children with FAS were significantly more likely to be older, American Indians/Alaska Natives, Black, not Hispanic, unmarried, unemployed, and without prenatal care, to smoke during pregnancy, to have a lower educational level, and to have more live born children. A significant proportion of mothers (9-29%) had another child with suspected alcohol effects. Compared to all US mothers, they were also significantly more likely to be on public assistance, to be on Medicaid at their child's birth, to have received treatment for alcohol abuse, to have confirmed alcoholism, to have used marijuana or cocaine during pregnancy, to have their baby screen positive for alcohol or drugs at birth, to have had an induced abortion, to have had a history of mental illness, to have been involved in binge drinking during pregnancy, and to have drunk heavily (7 days/week) during pregnancy. These findings suggest that it is possible to identify women who are at high risk of having a child with FAS and target these women for interventions.

Lack of maternal folic acid supplementation is associated with heart defects in Down syndrome: a report from the National Down Syndrome Project.

BACKGROUND: Maternal folic acid supplementation has been associated with a reduced risk for neural tube defects and may be associated with a reduced risk for congenital heart defects and other birth defects. Individuals with Down syndrome are at high risk for congenital heart defects and have been shown to have abnormal folate metabolism. METHODS: As part of the population-based case-control National Down Syndrome Project, 1011 mothers of infants with Down syndrome reported their use of supplements containing folic acid. These data were used to determine whether a lack of periconceptional maternal folic acid supplementation is associated with congenital heart defects in Down syndrome. We used logistic regression to test the relationship between maternal folic acid supplementation and the frequency of specific heart defects correcting for maternal race or ethnicity, proband sex, maternal use of alcohol and cigarettes, and maternal age at conception. RESULTS: Lack of maternal folic acid supplementation was more frequent among infants with Down syndrome and atrioventricular septal defects (odds ratio [OR], 1.69; 95% confidence interval [CI], 1.08-2.63; p = 0.011) or atrial septal defects (OR, 1.69; 95% CI, 1.11-2.58; p = 0.007) than among infants with Down syndrome and no heart defect. Preliminary evidence suggests that the patterns of association differ by race or ethnicity and sex of the proband. There was no statistically significant association with ventricular septal defects (OR, 1.26; 95% CI, 0.85-1.87; p = 0.124). CONCLUSIONS: Our results suggest that lack of maternal folic acid supplementation is associated with septal defects in infants with Down syndrome. Birth Defects Research (Part A), 2011. © 2011 Wiley-Liss, Inc.

Geocoding capacity of birth defects surveillance programs: results from the National Birth Defects Prevention Network Geocoding Survey.

A Web-based survey focusing on geocoding of birth defects data was developed and administrated to gain an understanding of the capacity of state birth defects programs to geocode maternal residence and to identify barriers to geocoding birth defects data. The survey consisted of 21 questions related to geocoding of maternal residence, type of software used, barriers to geocoding, and data linkage. In August 2007, an e-mail with a Web link to the survey was sent to all state birth defects program contacts in the United States, including the District of Columbia, Puerto Rico, and the Centers for Disease Control and Prevention (CDC) requesting they complete the online survey. By October 2007, 39 (74%) out of 53 birth defects program contacts completed the survey. Although nearly all birth defects programs collect maternal residential data, many are not currently geocoding that data. Results indicated that 97% of the programs that completed the survey reported they collected data on maternal residence, 53% of which reported that the birth defects surveillance data were geocoded to the street address level using maternal residential address at delivery. Twenty six percent of the programs that do not currently geocode the data identified "Software and address reference file are not available" as the most significant barrier to geocoding; another 16% chose "Lack of funding" as the most significant barrier to geocoding. Since geocoding is an important component of spatial analyses used to detect potential clusters of birth defects, leveraging resources to overcome the barriers that prevent programs from geocoding is important.

Synthesis and characterization of mixed methyl/allyl monolayers on Si(111).

The formation of mixed methyl/allyl monolayers has been accomplished through a two-step halogenation/alkylation reaction on Si(111) surfaces. The total coverage of alkylated Si, the surface recombination velocities, and the degree of surface oxidation as a function of time have been investigated using X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and microwave conductivity measurements. The total coverage of alkyl groups, the rate of oxidation, and the surface recombination velocities of Si(111) terminated by mixed monolayers were found to be close to those observed for CH(3)-Si(111) surfaces. Hence, the mixed-monolayer surfaces retained the beneficial properties of CH(3)-Si(111) surfaces while allowing for convenient secondary surface functionalization.

Consequences of polylactide stereochemistry on the properties of polylactide-polymenthide-polylactide thermoplastic elastomers.

A series of polylactide-polymenthide-polylactide triblock copolymers containing either amorphous poly(D,L-lactide) or semicrystalline, enantiopure poly(L-lactide) or poly(D-lactide) end segments were synthesized. Small-angle X-ray scattering and differential scanning calorimetry data were consistent with microphase separation of these materials. The Young's moduli and ultimate tensile strengths of the semicrystalline triblock copolymers were 2- and 3-fold greater, respectively, than their amorphous analogs. Symmetric (50:50) and asymmetric (95:5) blends of the triblock copolymers containing two different enantomeric forms of the polylactide segments formed stereocomplex crystallites, as revealed by wide-angle X-ray scattering and differential scanning calorimetry. Compared to the enantiopure analogs, these blends exhibited similar ultimate elongations and tensile strengths, but significantly increased Young's moduli. Collectively, these results demonstrate that the properties of these new biorenewable thermoplastic elastomers can be systematically modulated by changing the stereochemistry of the polylactide end blocks.

Maternal age and risk for trisomy 21 assessed by the origin of chromosome nondisjunction: a report from the Atlanta and National Down Syndrome Projects.

We examined the association between maternal age and chromosome 21 nondisjunction by origin of the meiotic error. We analyzed data from two population-based, case-control studies: Atlanta Down Syndrome Project (1989-1999) and National Down Syndrome Project (2001-2004). Cases were live born infants with trisomy 21 and controls were infants without trisomy 21 delivered in the same geographical regions. We enrolled 1,215 of 1,881 eligible case families and 1,375 of 2,293 controls. We report four primary findings. First, the significant association between advanced maternal age and chromosome 21 nondisjunction was restricted to meiotic errors in the egg; the association was not observed in sperm or in post-zygotic mitotic errors. Second, advanced maternal age was significantly associated with both meiosis I (MI) and meiosis II (MII). For example, compared to mothers of controls, mothers of infants with trisomy 21 due to MI nondisjunction were 8.5 times more likely to be >or=40 years old than 20-24 years old at the birth of the index case (95% CI=5.6-12.9). Where nondisjunction occurred in MII, mothers were 15.1 times more likely to be >or=40 years (95% CI = 8.4-27.3). Third, the ratio of MI to MII errors differed by maternal age. The ratio was lower among women <19 years of age and those >or=40 years (2.1, 2.3, respectively) and higher in the middle age group (3.6). Lastly, we found no effect of grand-maternal age on the risk for maternal nondisjunction. This study emphasizes the complex association between advanced maternal age and nondisjunction of chromosome 21 during oogenesis.

Renewable-resource thermoplastic elastomers based on polylactide and polymenthide.

An alpha,omega-functionalized polymenthide was synthesized by the ring-opening polymerization of menthide in the presence of diethylene glycol with diethyl zinc as the catalyst. Termination with water afforded the dihydroxy polymenthide. The reaction of this telechelic polymer with triethylaluminum formed the corresponding aluminum alkoxide macroinitiator that was used for the controlled polymerization of lactide to yield biorenewable polylactide-b-polymenthide-b-polylactide triblock copolymers. The molecular weight and chemical composition were easily adjusted by the monomer-to-initiator ratios. Microphase separation in these triblock copolymers was confirmed by small-angle X-ray scattering and differential scanning calorimetry. A representative triblock was prepared with a hexagonally packed cylindrical morphology as determined by small-angle X-ray scattering, and tensile testing was employed to assess the mechanical behavior. On the basis of the ultimate elongations and elastic recovery, these triblock copolymers behaved as thermoplastic elastomers.