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Gary M Shaw

Publications and source records attributed to Gary M Shaw.

At least 73 records · Page 4Linked to original sources
PubMed2003

Maternal periconceptional alcohol consumption and risk for conotruncal heart defects.

BACKGROUND: In this study we investigated whether the risk of delivering infants with conotruncal heart defects was increased among mothers who consumed alcohol during the periconceptional period (i.e., 1 month before conception to 3 months after conception). METHODS: Data were obtained from a population-based case-control study of California births from 1987-1988. Information concerning alcohol consumption was obtained via telephone interviews with mothers of 207 (87% of eligibles) case infants and 481 (76%) nonmalformed control infants. RESULTS: Bivariate results indicated that relative to nonconsumers, women who consumed alcohol less than once a week had a 1.3-fold increased risk of delivering infants with a conotruncal heart defect (95% confidence interval (CI) 1.0, 1.9), and women who consumed alcohol once a week or more had a 1.9-fold increased risk (95% CI 1.0, 3.4). The risks associated with consuming five or more drinks per drinking occasion were 1.6 (95% CI 0.8, 3.2) for less than once a week, and 2.4 for once a week or more (95% CI 0.6, 9.7). The results for the phenotypic subgroups were similar to those for all cases. Adjustment for potential covariates resulted in somewhat weaker, but still elevated, risks. CONCLUSIONS: This study found that the risk of conotruncal heart defects in offspring was moderately elevated among women who consumed alcoholic beverages during the periconceptional period, and that risk was higher with increased frequency of drinking or increased number of drinks consumed per occasion. Most of the risk estimates were imprecise, and chance could not be ruled out as an explanation for the observed findings.

Adult↗
PubMed2003

Differential risks to males and females for congenital malformations among 2.5 million California births, 1989-1997.

BACKGROUND: Although many studies have observed variations in the prevalence of specific malformations by sex, there is a lack of population-based data on potential malformation prevalence differences by sex at birth. METHODS: Our objective was to explore differences in the prevalence of structural congenital malformation phenotypes between sexes in a California population of 2.5 million live- and stillbirths, using data from a population-based active surveillance system. Ascertainment was performed among offspring of California women who delivered in nonmilitary hospitals during the period of 1989-1997. Malformations were grouped according to the four-digit malformation codes of the British Pediatric Association. RESULTS: Overall, 32,619 males and 21,835 females were considered to have structural congenital malformations, with prevalences of 2.52% and 1.76%, respectively. Thus, males demonstrated a malformation prevalence that was 22% higher than that in females. Using a criterion of a 40% increase or decrease in the relative risk for males, increased risks for 15 and decreased risks for 17 specific malformation categories were observed. Increased risks were associated with most organ systems, with the notable exception of the nervous system (increased risks for nervous system malformations were observed among female births). Risks were not substantially influenced by adjusting for maternal age, race/ethnicity, parity, or education. CONCLUSIONS: Our observations extend the relatively few studies that have investigated differential prevalences of a large number of specific structural malformations between male and female births.

California↗
PubMed2003

Diet quality and risk of neural tube defects.

Many studies have examined the impact of single nutrients on neural tube defect (NTD) risk, particularly folate. The impact of dietary patterns or nutrients in combination has received much less attention. This study examines the association of diet quality with NTD risk, using food frequency data from a population-based case-control study of NTDs (n=454 cases and 462 controls). The diet quality score was based on low (<10th percentile among controls) versus high (>90th percentile) values for intakes of iron, vitamins B(6) and A, calcium, folate, and percentage of kilocalories from fat and from sweets (range=0-14). Women with a low score (i.e., <4, or <10th percentile) had an elevated risk of an NTD-affected pregnancy (odds ratio 1.6, 95% CI 1.0-2.6). Stratified analyses suggested that the effect may be restricted to certain groups of women who may be at greater nutritional risk (i.e., women who did not take vitamin supplements or regularly consume breakfast cereals before pregnancy).

Adult↗
PubMed2003

Homocysteine remethylation enzyme polymorphisms and increased risks for neural tube defects.

Folic acid supplementation can effectively reduce the risk of neural tube defects (NTDs); however, the mechanism underlying this beneficial effect remains unclear. Recent evidence suggests that certain folate pathway genes, as well as those related to homocysteine metabolism might be contributing to this effect. The purpose of this study is to investigate whether gene polymorphisms of methionine synthase (MTR) and methionine synthase reductase (MTRR) are involved in the risk for NTDs, specifically spina bifida. We detected MTR A2756G and MTRR A66G polymorphisms using PCR-RFLP analysis in a group of NTD infants, their mothers and normal controls. We found that infants with the MTRR mutant genotype had a 2.6-fold higher risk of NTDs when compared to the AA genotype (OR = 2.6, 95%CI = 1.3-5.3). Mothers with the MTRR mutant genotype also had a 1.9-fold higher risk of having an NTD baby compared to AA genotype (OR = 1.9, 95%CI = 1.1-3.1). Infants who carry mutant alleles for both MTRR and MTR had exceptionally elevated NTD risks, with odds ratios of 5.1 compared to infants with the wild type genotype at both loci (AA + AA) (OR = 5.1, 95%CI = 1.7-15.4). A comparable result was observed in the mothers of NTD cases (OR = 2.1, 95%CI = 1.0-4.7). Our results indicate that MTRR and MTR genes may interact to increase the infants' NTD risks. These results did not appear to be influenced by maternal periconceptional folic acid intake. However,the sample size of this study was limited, and a larger population study is needed to pursue these initial observations.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed2003

Social networks and risk of neural tube defects.

The contribution of social support and social networks to risk of neural tube defects (NTDs) has not been explored, despite evidence that various aspects of the social environment contribute to their etiology. Using data from a population-based case-control study of deliveries occurring in California from 1989 to 1991, this study investigates whether social networks, as measured by the presence and frequency of various types of social contacts, are associated with NTD risk. In-person interviews were conducted with 538 (88% of eligible) mothers of NTD cases and with mothers of 539 non-malformed controls (88%) on average 5 months from the term delivery date. Unadjusted results indicate that women who reported having close friends, close relatives, or monthly contacts with close friends or relatives had 30-70% lower risks of having NTD-affected pregnancies, relative to women reporting 'none' to any of these measures. Only the presence of close friends was associated with reduced NTD risk after adjustment for other aspects of the social network and several potential covariates. This study is the first to investigate the association between social networks and risk of NTDs. Stronger inferences await replication and extension of these results.

California↗
PubMed2003

Socio-economic status and risk of conotruncal heart defects and orofacial clefts.

Studies of socio-economic status (SES) have figured prominently in research related to a variety of health outcomes, although the question remains as to whether SES contributes to the aetiologies of congenital anomalies. This study examines the association of SES with risks of conotruncal heart defects and orofacial clefts, using interview data from 696 case mothers (86% of eligible) and 734 (78%) control mothers from a population-based case-control study. Socio-economic measures from maternal interview included mother's education and employment. Reported addresses were linked with the US census to characterise six measures of neighbourhood SES (education, poverty, unemployment, occupation, crowding and rental occupancy). Results were adjusted for race-ethnicity, multivitamin/mineral supplement intake, cigarette smoking and binge drinking. Results for individual and neighbourhood measures suggested that low SES was associated with increased risk of d-transposition of the great arteries (dTGA), reduced risk of tetralogy of Fallot (TOF), but was not associated with risk of orofacial clefts. For example, when examining odds ratios (OR) that compared risks among women whose neighbourhoods were in the lowest vs. highest quartile of the census-based SES measures, ORs for five of the six measures were> 1.4 for dTGA, and ORs for all six measures were < 0.7 for TOF. ORs for clefts tended to be closer to 1. This study suggests that SES risks are birth defect specific.

Adult↗
PubMed2003

Neural tube defects associated with maternal periconceptional dietary intake of simple sugars and glycemic index.

BACKGROUND: Maternal diabetes, prepregnancy obesity, hyperinsulinemia, and intakes of sweets have been associated with increased risks of neural tube defects (NTDs). The interdependence of these factors suggests a common pathogenesis via altered glycemic control and insulin demand. OBJECTIVE: We investigated whether maternal periconceptional dietary intakes of sucrose, glucose, fructose, and foods with higher glycemic index values influence the risk of having NTD-affected pregnancies. DESIGN: In a population-based case-control study, all hospitals in 55 of the 58 counties in California participated. In-person interviews were conducted with the mothers of 454 NTD cases (including fetuses and infants who were electively terminated, stillborn, or born alive) and with the mothers of 462 nonmalformed controls within an average of 5 mo from the term delivery date. The risk of having an NTD-affected pregnancy was the main outcome measure. RESULTS: Risks of having an NTD-affected pregnancy were not substantially elevated in relation to periconceptional intakes of glucose or fructose. Elevated risks of approximately 2-fold were observed for higher intakes of sucrose and foods with higher glycemic index values. Elevated risks were observed for high sucrose intake irrespective of whether adjustment was made for other covariates such as maternal folic acid intake. For higher glycemic index values, adjusted elevated risks of > or = 4-fold were observed in women whose body mass index (in kg/m(2)) was > 29. CONCLUSION: Our observed associations support observations that potential problems in glucose control are associated with NTD risk even among nondiabetic women.

Adult↗
PubMed2003

Strenuous work, nutrition and adverse pregnancy outcomes: a brief review.

This brief review explores the available epidemiologic data to investigate the question of whether strenuous work by women during pregnancy in developing countries influences micronutrient status and thereby increase risks of adverse pregnancy outcomes. Some data exist on the potential relationship between strenuous work or physical activity and nutrient compromise, strenuous work or physical activity and adverse reproductive outcomes and micronutrient intakes or status and adverse reproductive outcomes. No substantial body of data exists that has directly investigated the potential causal path of whether strenuous work during pregnancy alters micronutrient status leading to adverse reproductive outcome. Search of the literature identified only a few papers from developing countries that provided even remotely related data on the topic. Thus, the available data are insufficient for drawing firm inferences that strenuous work, in a developing country, alters a pregnant woman's nutritional status and therefore affects her risk of an adverse pregnancy outcome. Effects on nutritional status, micronutrients in particular, of pregnant women from strenuous physical activities at work or in other lifestyle events require further study in developing countries.

Developing Countries↗
PubMed2003

Trihalomethane exposures from municipal water supplies and selected congenital malformations.

BACKGROUND: Concerns about potential health effects of trihalomethanes (THMs) have prompted investigations on whether infants whose mothers were periconceptionally exposed to drinking water containing THMs are at greater risk of congenital malformations. METHODS: We used two large case-control maternal interview studies that were conducted among California deliveries from 1987 through 1991. One study comprised 538 infants/fetuses with neural tube defects (NTDs) and 539 nonmalformed control infants. The second study included an additional 265 infants with NTDs, 207 infants with conotruncal heart defects, 409 infants with orofacial clefts, and 481 control infants. Expert personnel from municipal water companies estimated THM levels for a particular residence and specific periconceptional time period using quarterly monitoring measurements. Estimates were also made for four individual THM levels and for the total THM level. RESULTS: NTD risk in the first study was inversely associated with total THM exposure. Although the second study did not show the same inverse relationship for NTDs, there were no positive associations of NTDs or the other malformations with total THM as estimated from continuous models. Elevated risks were observed for the lowest category of exposure (1-24 ppb), but risks were either not substantially elevated or were imprecise for higher exposure levels. Thus no evidence was observed for an exposure-response relation. CONCLUSIONS: Our results do not provide a clear pattern of association between THM exposure and risks of specific congenital malformations. Imprecise exposure measures coupled with a lack of information about other possible sources of THM exposure may have caused associations to be underestimated.

California↗
PubMed2003

Hypospadias in California: trends and descriptive epidemiology.

BACKGROUND: The occurrence of hypospadias has been reported to be increasing. The objectives of this study were to extend the literature on the descriptive epidemiology of hypospadias and to determine whether its birth prevalence increased in California in recent years. We used actively ascertained, population-based data for which detailed clinical descriptions permitted careful phenotypic classifications. METHODS: We examined registry data on 5838 male live births and stillbirths that occurred in California from 1984 through 1997. To reduce pathogenic heterogeneity, cases were classified as mild, severe, or not otherwise specified based on the anatomic position of the urethral opening. We also classified cases as isolated or nonisolated based on the presence and type of accompanying malformations. We used multivariable Poisson regression analysis to examine time trends and risk factors. RESULTS: There was no evidence for an increase in prevalence of any of the case groups between 1989 and 1997. The adjusted relative risk (RR) for change in prevalence per year of isolated severe cases was 0.99 (95% confidence interval = 0.96-1.03). Adjusted RRs indicated increased risks for specific types of hypospadias with maternal non-Hispanic white race-ethnicity, higher education, older age, and nulliparity. Delivery before 37 weeks and multiple births tended either not to be associated with risk or to be associated with reduced risk. Lower birthweight was associated with increased risk for all case groups. CONCLUSIONS: This study suggests that hypospadias prevalence has not been increasing in California in recent years. Differences by phenotype suggest that examining certain phenotypes separately could help to understand hypospadias etiology.

California↗
PubMed2003

Fertility treatments and craniosynostosis: California, Georgia, and Iowa, 1993-1997.

OBJECTIVE: Craniosynostosis, a malformation caused by premature closure of 1 or more cranial sutures, is a rare birth defect usually of unknown cause; however, it is often associated with advanced maternal age. Because fertility treatments are also associated with increased maternal age, this study investigated the possible association between fertility treatments and craniosynostosis. METHODS: Data from the Birth Defect Risk Factor Surveillance study were used, which included infants who were delivered from 1993 through 1997 in California, Georgia, and Iowa. Cases were defined as infants who had nonfamilial, nonsyndromic craniosynostosis and were ascertained through existing birth defect surveillance systems. Controls, infants without birth defects, were selected from the same regions and time period. RESULTS: Mothers of 99 case infants and 777 control infants from the 3 study locations participated in this study by completing a telephone interview. Unadjusted analyses showed associations with craniosynostosis for mothers who had used clomiphene citrate (odds ratio[OR]: 3.8; 95% confidence interval [CI]: 1.1-12.3), artificial insemination (OR: 4.2; 95% CI: 0.8-9.4), or assisted reproductive techniques (OR: 4.2; 95% CI: 0.5-27.3). CONCLUSIONS: This is the first study that has found associations between fertility treatments and craniosynostosis. However, the numbers are small; therefore, the results should be viewed with caution.

California↗
PubMed2002

Maternal periconceptional vitamin use, genetic variation of infant reduced folate carrier (A80G), and risk of spina bifida.

Women who consume folic acid in early pregnancy reduced their risks for delivering offspring with neural tube defects (NTDs). The underlying process by which folic acid facilitated this risk reduction is unknown. Investigating genetic variation that influences cellular absorption, transport, and metabolism of folate will help fill this data gap. We focused our studies on a candidate gene that is involved in folate transport, the reduced folate carrier 1 (RFC1). Using data from a California population-based case control interview study (1989-1991 birth cohorts), we investigated whether spina bifida risk was influenced by an interaction between a polymorphism of infant RFC1 at nucleotide 80 (A80G) and maternal periconceptional use of vitamins containing folic acid. Allelic variants of RFC1 were determined by genotyping 133 live-born spina bifida case infants and 188 control infants. The percentages of case infants with the A80/A80, G80/G80, and G80/A80 genotypes were 27.2%, 28.0%, and 44.7%, respectively. The percentages of control infants were similar: 26.1%, 29.3%, and 44.7%. Odds ratios of 1.0 (95% confidence interval 0.5-2.0) for the G80/G80 genotype and 1.1 (0.6-2.0) for the G80/A80 genotype were observed relative to the A80/A80 genotype. Among mothers who did not use vitamins, spina bifida risk was 2.4 (0.8-6.9) for infants with genotype G80/G80 compared to those with A80/A80 genotype. Among mothers who did use vitamins, the risk was 0.5 (0.1-3.1) for infants with the G80/G80 genotype. Although this study did not find an increased spina bifida risk for infants who were heterozygous or homozygous for RFC1 A80G, it did reveal modest evidence for a gene-nutrient interaction between infant homozygosity for the RFC1 G80/G80 genotype and maternal periconceptional intake of vitamins containing folic acid on the risk of spina bifida.

Amino Acid Substitution↗
PubMed2002

Ambient air pollution and risk of birth defects in Southern California.

The authors evaluated the effect of air pollution on the occurrence of birth defects ascertained by the California Birth Defects Monitoring Program in neonates and fetuses delivered in southern California in 1987-1993. By using measurements from ambient monitoring stations of carbon monoxide (CO), nitrogen dioxide, ozone, and particulate matter <10 microm in aerodynamic diameter, they calculated average monthly exposure estimates for each pregnancy. Conventional, polytomous, and hierarchical logistic regression was used to estimate odds ratios for subgroups of cardiac and orofacial defects. Odds ratios for cardiac ventricular septal defects increased in a dose-response fashion with increasing second-month CO exposure (odds ratio (OR)(2nd quartile) CO = 1.62, 95% confidence interval (CI): 1.05, 2.48; OR(3rd quartile) CO = 2.09, 95% CI: 1.19, 3.67; OR(4th quartile) CO = 2.95, 95% CI: 1.44, 6.05). Similarly, risks for aortic artery and valve defects, pulmonary artery and valve anomalies, and conotruncal defects increased with second-month ozone exposure. The study was inconclusive for other air pollutants. The authors' results are supported by the specificity of the timing of the effect and some evidence from animal data; however, this is the first known study to link ambient air pollution during a vulnerable window of development to human malformations. Confirmation by further studies is needed.

Air Pollutants↗
PubMed2002

Congenital malformations in offspring of Vietnamese women in California, 1985-97.

BACKGROUND: Little is known about reproductive outcome risks for Vietnamese women delivering infants and fetuses in the U.S. METHODS: Using data from a large population-based registry, we explored risks of selected congenital malformation phenotypes in offspring of Vietnamese women in California. Data were derived from the California Birth Defects Monitoring Program, a population-based active surveillance system for collecting information on infants and fetuses with congenital malformations using multiple source ascertainment. Approximately 3.4 million births (liveborn and stillborn) occurred during the ascertainment period, 1985-97. Information on maternal race/ethnic background was obtained from California birth certificate and fetal death files. Vietnamese women delivered 45,453 births and 1,257,853 births were delivered to non-Hispanic white women. RESULTS: The overall prevalence of structural congenital malformations was 1.92 among Vietnamese and 2.63 among non-Hispanic whites per 100 births and fetal deaths. Grouping by 20 3-digit malformation codes of the International Classification of Diseases-Ninth Revision revealed relative risks of 0.8 or less for spina bifida, eye, upper alimentary, genital, urinary, musculoskeletal, "other" limb, and "other" musculoskeletal anomalies, and relative risks of 1.3 or more for anencephaly and chromosomal anomalies. Grouping by the more specific 4-digit malformation codes revealed 50, among 178, malformation groupings with associated relative risks of >or=1.3 or <or=0.8. Seventeen relative risk estimates suggested elevated risks for Vietnamese births, and 33 estimates suggested lowered risks for Vietnamese, relative to non-Hispanic white births. Simultaneous adjustment for maternal age, plurality, and child sex, did not substantially alter observed risks. CONCLUSIONS: These data contribute to a relatively sparse literature about an important subgroup of the U.S. population, but can not elucidate whether increased or decreased risks among Vietnamese are related to potential underlying genetic susceptibilities, to cultural, social, or political differences that could modify exposures, or to the many potential combinations between susceptibilities and exposures.

California↗
PubMed2002

Prevalence of spina bifida and anencephaly during the transition to mandatory folic acid fortification in the United States.

BACKGROUND: In 1992, the United States Public Health Service recommended that all women of childbearing age consume 400 microg of folic acid daily. The Food and Drug Administration authorized the addition of synthetic folic acid to grain products in March 1996 with mandatory compliance by January 1998. The impact of these public health policies on the prevalence of neural tube defects needs to be evaluated. We sought to determine the prevalences of spina bifida and anencephaly during the transition to mandatory folic acid fortification. METHODS: Twenty-four population-based surveillance systems were used to identify 5,630 cases of spina bifida and anencephaly from 1995-99. Cases were divided into three temporal categories depending on whether neural tube development occurred before folic acid fortification (January 1995 to December 1996), during optional fortification (January 1997 to September 1998), or during mandatory fortification (October 1998 to December 1999). Prevalences for each defect were calculated for each time period. Data were also stratified by programs that did and did not ascertain prenatally diagnosed cases. RESULTS: The prevalence of spina bifida decreased 31% (prevalence ratio [PR] = 0.69, 95% confidence interval [CI] = 0.63-0.74) from the pre- to the mandatory fortification period and the prevalence of anencephaly decreased 16% (PR = 0.84, 95% CI = 0.75-0.95). Stratification by prenatal ascertainment did not alter results for spina bifida but did impact anencephaly trends. CONCLUSIONS: The decline in the prevalence of spina bifida was temporally associated with folic acid fortification of US grain supplies. The temporal association between fortification and the prevalence of anencephaly is unclear.

Anencephaly↗
PubMed2002

Integration of DNA sample collection into a multi-site birth defects case-control study.

BACKGROUND: Advances in quantitative analysis and molecular genotyping have provided unprecedented opportunities to add biological sampling and genetic information to epidemiologic studies. The purpose of this article is to describe the incorporation of DNA sample collection into the National Birth Defects Prevention Study (NBDPS), an ongoing case-control study in an eight-state consortium with a primary goal to identify risk factors for birth defects. METHODS: Babies with birth defects are identified through birth defects surveillance systems in the eight participating centers. Cases are infants with one or more of over 30 major birth defects. Controls are infants without defects from the same geographic area. Epidemiologic information is collected through an hour-long interview with mothers of both cases and controls. We added the collection of buccal cytobrush DNA samples for case-infants, control-infants, and their parents to this study. RESULTS: We describe here the methods by which the samples have been collected and processed, establishment of a centralized resource for DNA banking, and quality control, database management, access, informed consent, and confidentiality issues. CONCLUSIONS: Biological sampling and genetic analyses are important components to epidemiologic studies of birth defects aimed at identifying risk factors. The DNA specimens collected in this study can be used for detection of mutations, study of polymorphic variants that confer differential susceptibility to teratogens, and examination of interactions among genetic risk factors. Information on the methods used and issues faced by the NBDPS may be of value to others considering the addition of DNA sampling to epidemiologic studies.

Case-Control Studies↗