Infant C677T MTHFR polymorphism and severe mental retardation.

Background: We investigated whether infants with homozygous genotype TT of the MTHFR gene were at increased risk of severe mental retardation.

Methods: One hundred children with severe mental retardation (cases) were investigated from a large geographic-based study of infants born in California in 1992-1993. Cases were compared to 743 randomly selected nonmalformed control infants born in California during 1987-1991.

Schizencephaly: heterogeneous etiologies in a population of 4 million California births.

Schizencephaly is a rare congenital brain defect characterized by gray matter lined clefts of the cerebral mantle, frequently accompanied by other defects of the CNS such as absence of the corpus callosum. This study in a California population of >4 million births from 1985-2001 found a population prevalence of 1.54/100,000.

Risks for severe mental retardation occurring in isolation and with other developmental disabilities.

Individual and maternal characteristics as potential risk factors for having severe mental retardation (SMR) occurring with and without cerebral palsy (CP), epilepsy, or a pervasive developmental disorder (PDD) were explored among a cohort of 119,404 children without Down syndrome born in the California Central Valley in 1992 and 1993. Unadjusted and adjusted relative risks (RRs) and their 95% confidence intervals (CIs) based on the Poisson distribution were used to estimate the risks associated with each individual and maternal factor studied for each SMR diagnostic category. The most notable increased risks for SMR occurring in isolation or with CP or epilepsy was for children born low-birth-weight or preterm who were at a substantially increased risk (RRs 2.

Occurrence of low birthweight and preterm delivery among California infants before and after compulsory food fortification with folic acid.

Objectives: Studies suggest that folic acid intake influences the occurrence of low birthweight and preterm delivery. Since 1998, there has been compulsory fortification of flour and other grains with folic acid in the U.S.

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.

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.

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.

Risk of mental retardation among children born with birth defects.

Background: A paucity of epidemiologic research exists concerning the co-occurrence of birth defects and mental retardation (MR). Study of this co-occurrence may yield important clues about the causes of both.

Objective: To examine the co-occurrence of birth defects and MR, taking into consideration the type of birth defect, level of MR, co-occurrence of MR with other developmental disabilities, and individual and maternal factors.

Food fortification with folic acid and twinning among California infants.

This study sought to determine whether a change in twinning prevalence was associated with mandatory folic acid fortification. As of January 1998, it became mandatory in the United States that grain products be fortified with folic acid. The effectiveness of this fortification for neural tube defects has been explored, but other possible implications of fortification has not.

Maternal occupational chemical exposures and biotransformation genotypes as risk factors for selected congenital anomalies.

In a case-control study using an assessment of occupational tasks by an industrial hygienist, the authors investigated whether women's occupational exposures increased risks of delivering infants with cleft palate (CP), cleft lip with or without cleft palate (CLP), conotruncal defects, or limb deficiencies. For CP and CLP, exposures were further considered in the presence/absence of infant genetic variants for glutathione-S-transferase M1, glutathione-S-transferase T1, and N-acetyltransferases 1 and 2. The study included 1987-1989 California stillbirths and livebirths.

Timing of prenatal care initiation and risk of congenital malformations.

Background: Although previous studies provide some evidence that timing of prenatal care initiation is associated with risks of congenital malformation, the issue has not previously been examined in depth. This study uses data from a large population-based registry to explore the association of timing of prenatal care initiation with risks of selected congenital malformation phenotypes.

Methods: Data on cases were grouped according to four-digit malformation codes of the International Classification of Diseases, Ninth Revision (ICD-9).

Paternal occupational group and risk of offspring with neural tube defects.

Selected paternal occupations as well as specific occupational exposures to chemicals such as organic solvents have been suggested as possible risk factors for neural tube defects (NTD). We investigated data from a population-based, case-control study of fetuses and liveborn infants with NTDs among 1989-91 California births and fetal deaths. Interviews were conducted with mothers of 538 NTD cases and 539 non- malformed controls.

Maternal periconceptional vitamins: interactions with selected factors and congenital anomalies?

Background: The mechanisms by which folic acid may contribute to reductions in risk of several congenital anomalies are unknown. The data gap includes a lack of information on possible effect modification between maternal folic acid use and other maternal exposures. We hypothesized that effects of congenital anomalies associated with maternal fever, cigarette smoking or alcohol use would be modified by intake of vitamins.

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.