Increased risk for developmental disabilities in children who have major birth defects: a population-based study

National population-based estimates for major birth defects, 2016-2020

BACKGROUND

We provide updated crude and adjusted prevalence estimates of major birth defects in the United States for the period 2016-2020.

METHODS

Data were collected from 13 US population-based surveillance programs that used active or a combination of active and passive case ascertainment methods to collect all birth outcomes. These data were used to calculate pooled prevalence estimates and national prevalence estimates adjusted for maternal race/ethnicity for all conditions, and maternal age for trisomies and gastroschisis. Prevalence was compared to previously published national estimates from 1999 to 2014.

RESULTS

Adjusted national prevalence estimates per 10,000 live births ranged from 0.63 for common truncus to 18.65 for clubfoot. Temporal changes were observed for several birth defects, including increases in the prevalence of atrioventricular septal defect, tetralogy of Fallot, omphalocele, trisomy 18, and trisomy 21 (Down syndrome) and decreases in the prevalence of anencephaly, common truncus, transposition of the great arteries, and cleft lip with and without cleft palate.

CONCLUSION

This study provides updated national estimates of selected major birth defects in the United States. These data can be used for continued temporal monitoring of birth defects prevalence. Increases and decreases in prevalence since 1999 observed in this study warrant further investigation.

A comparison of infants' birth defects self-reported by mothers with data provided by general practitioners: Data from the Dutch Pregnancy Drug Register

BACKGROUND

Since the presence of a birth defect is often a primary outcome in drug-safety studies among pregnant women, researching the validity of data collection methods is imperative. The aim of this study is to compare self-reported birth defects in infants by mothers with the information provided by general practitioners (GP (singular) or GPs (plural)).

METHODS

Mothers who participated in the Dutch Pregnancy Drug Register reported information about possible birth defects of their infants via questionnaires. GPs were approached to provide information on possible birth defects of the same infants. All reported birth defects by mothers and GPs were blindly coded using the International Classification of Diseases, Tenth Revision (ICD-10) index and EUROCAT-classified as either a minor or major birth defect. Differences in reported birth defects between participants and GPs were assessed.

RESULTS

Participants and GPs (N = 551) reported 67 and 53 birth defects respectively, leading to a total of 120 birth defects among 65 infants. When both the GP and the participant reported a birth defect, 76.9% of these birth defects (N = 60) were coded with an identical ICD-10 code. Information on the absence of a birth defect and the presence of a major birth defect was identically reported by the GP and the mother in almost all cases (98.2%). Of the major birth defects reported by the GP, 67% could be matched with information provided by the participant, for 33% contradicting information was reported.

CONCLUSION

Self-reported questionnaire data on infants' birth defects from mothers yield fairly similar information compared to information obtained through GPs. Future studies should validate the accuracy of self-reported birth defects by mothers more extensively to improve the quality of drug safety studies during pregnancy.

Is teenage parenthood associated with early use of disability pension? Evidence from a longitudinal study

BACKGROUND

Over the past decades the number of young people using disability pensions (DP) has gradually increased in Europe but the reasons for this change are poorly understood. We hypothesize that teenage parenthood could be associated with an increased risk of receiving early DP. The aim of this study was to examine the association between having a first child at age 13-19 and receiving DP at age 20-42 (here called early DP).

METHODS

A longitudinal cohort study was undertaken based on national register data obtained from 410,172 individuals born in Sweden in 1968, 1969, and 1970. Teenage mothers and fathers were followed until age 42 and compared to non-teenage parent counterparts to examine their early receipt of DP. Descriptive analysis, Kaplan-Meier curves, and Cox regression analyses were performed.

RESULTS

The proportion of teenage parents was more than twice higher in the group that received early DP (16%) compared to the group that did not receive early DP (6%) during the study duration. A higher proportion of teenage mothers and fathers started to receive DP at 20-42 years old compared to non-teenage parents, and the difference between the two groups increased during the observation period. A strong association was observed between being a teenage parent and receiving early DP, significant both independently and after adjusting for the year of birth and the father's level of education. From the age of 30 to 42 years, teenage mothers used early DP more often than teenage fathers or non-teenage parents, and this difference also increased during the follow-up period.

CONCLUSION

A strong association was found between teenage parenthood and the use of DP between 20 and 42 years of age. Teenage mothers used DP more than teenage fathers and non-teenage parents.

Adverse perinatal conditions and receiving a disability pension early in life

OBJECTIVE

The number of young adults on disability pension (DP) is increasing in European countries, creating a need to understand the related risk factors. This study aimed to determine whether adverse perinatal conditions are associated with receiving a DP early in life.

METHODS

This longitudinal cohort study consisted of all persons (N = 453,223) born in Sweden during 1973-1977, observed from 1991 through 2010 when they were aged between 16 and 37 years. Statistics Sweden provided linked national data on the children and their parents. We used logistic regression to assess the association between perinatal health conditions (birth defect, Apgar score, and small for gestational age) and receiving a DP, adjusting for maternal education and the sex of the child.

RESULTS

New recipients of DP were significantly more likely to have had a birth defect (adjusted odds ratio [AOR] 2.74, 95% CI: 2.49-3.00), to have had low Apgar score (AOR 2.12, 95% CI: 1.77-2.52), to have been small for gestational age (AOR 1.73, 95% CI: 1.54-1.94) and to be females (AOR 1.55, 95% CI: 1.46-1.64). Higher maternal education was associated with lower odds of receiving a DP (AOR 0.74, 95% CI: 0.69-0.79) for those with high school education and (AOR 0.67, 95% CI: 0.59-0.75) for those with university education. Age-stratified analysis confirmed increased odds of receiving a DP among those with birth defects and small for gestational age, but this effect reduced with increasing age. Apgar score was significantly associated with starting to receive a DP at ages 16-18 and 19-29, but not at ages 30-33. Women had lower odds of receiving a DP at ages 16-18 (AOR 0.73, 95% CI: 0.64-0.85); however, this reversed from age 19 and upwards (AOR 1.53, 95% CI: 1.41-1.67) and (AOR 2.16, 95% CI: 1.95-2.40) for the age groups of 19-29 and 30-33, respectively. Persons with high maternal education were less likely to receive a DP regardless of age at receiving a DP.

CONCLUSION

Having a birth defect was the strongest indicator of receiving a DP during early adulthood, followed by small for gestational age and low Apgar score. Overall, the effects of the studied perinatal health conditions were pronounced in those who received a DP at 16-18 years, but this effect weakened with increasing age at receiving a DP. Our findings suggest that policies and programs geared at promoting optimal health at birth might contribute to a reduction in receiving a DP.

National population-based estimates for major birth defects, 2010-2014

BACKGROUND

Using the National Birth Defects Prevention Network (NBDPN) annual data report, U.S. national prevalence estimates for major birth defects are developed based on birth cohort 2010-2014.

METHODS

Data from 39 U.S. population-based birth defects surveillance programs (16 active case-finding, 10 passive case-finding with case confirmation, and 13 passive without case confirmation) were used to calculate pooled prevalence estimates for major defects by case-finding approach. Fourteen active case-finding programs including at least live birth and stillbirth pregnancy outcomes monitoring approximately one million births annually were used to develop national prevalence estimates, adjusted for maternal race/ethnicity (for all conditions examined) and maternal age (trisomies and gastroschisis). These calculations used a similar methodology to the previous estimates to examine changes over time.

RESULTS

The adjusted national birth prevalence estimates per 10,000 live births ranged from 0.62 for interrupted aortic arch to 16.87 for clubfoot, and 19.93 for the 12 critical congenital heart defects combined. While the birth prevalence of most birth defects studied remained relatively stable over 15 years, an increasing prevalence was observed for gastroschisis and Down syndrome. Additionally, the prevalence for atrioventricular septal defect, tetralogy of Fallot, omphalocele, and trisomy 18 increased in this period compared to the previous periods. Active case-finding programs generally had higher prevalence rates for most defects examined, most notably for anencephaly, anophthalmia/microphthalmia, trisomy 13, and trisomy 18.

CONCLUSION

National estimates of birth defects prevalence provide data for monitoring trends and understanding the impact of these conditions. Increasing prevalence rates observed for selected conditions warrant further examination.

Maternal residential exposure to specific agricultural pesticide active ingredients and birth defects in a 2003-2005 North Carolina birth cohort

BACKGROUND

Previously we observed elevated odds ratios (ORs) for total pesticide exposure and 10 birth defects: three congenital heart defects and structural defects affecting the gastrointestinal, genitourinary and musculoskeletal systems. This analysis examines association of those defects with exposure to seven commonly applied pesticide active ingredients.

METHODS

Cases were live-born singleton infants from the North Carolina Birth Defects Monitoring Program linked to birth records for 2003-2005; noncases served as controls (total n = 304,906). Pesticide active ingredient exposure was assigned using a previously constructed metric based on crops within 500 m of residence, dates of pregnancy, and likely chemical application dates for each pesticide-crop combination. ORs (95% CI) were estimated with logistic regression for categories of exposure compared to unexposed. Models were adjusted for maternal race/ethnicity, age at delivery, education, marital status, and smoking status.

RESULTS

Associations varied by birth defect and pesticide combinations. For example, hypospadias was positively associated with exposures to 2,4-D (OR_{50th to <90th percentile} : 1.39 [1.18, 1.64]), mepiquat (OR_{50th to <90th percentile} : 1.10 [0.90, 1.34]), paraquat (OR_{50th to <90th} : 1.14 [0.93, 1.39]), and pendimethalin (OR_{50th to <90th} : 1.21 [1.01, 1.44]), but not S-metolachlor (OR_{50th to <90th} : 1.00 [0.81, 1.22]). Whereas atrial septal defects were positively associated with higher levels of exposure to glyphosate, cyhalothrin, S-metolachlor, mepiquat, and pendimethalin (ORs ranged from 1.22 to 1.35 for 50th to <90th exposures, and 1.72 to 2.09 for >90th exposures); associations with paraquat were null or inconsistent (OR 50th to <90th: 1.05 (0.87, 1.27).

CONCLUSION

Our results suggest differing patterns of association for birth defects with residential exposure to seven pesticide active ingredients in North Carolina.

Comprehensive investigation of congenital anomalies in cerebral palsy: protocol for a European-Australian population-based data linkage study (The Comprehensive CA-CP Study)

INTRODUCTION

Cerebral palsy (CP), an umbrella term for non-progressive conditions of cerebral origin resulting in motor impairments, is collectively the most common cause of physical disability in childhood. Cerebral and/or non-cerebral congenital anomalies are present in 15%-40% of children with CP. In order to identify effective prevention strategies for this substantial proportion of CP, a comprehensive understanding of the epidemiology of these congenital anomalies is required. International collaboration is needed, as previous attempts have fallen short due to a lack of power, since the anomalies are individually rare and CP comprises many clinical descriptions. The aim of this study is to generate new knowledge about the aetiologies of CP through a focused investigation into the role of congenital anomalies.

METHODS AND ANALYSIS

This collaborative, population-based data linkage study includes nine geographic regions (six in Europe, three in Australia) served by both congenital anomaly and CP registers. Register data for children with CP (both with and without congenital anomalies) and children with specific congenital anomalies (without CP) born between 1991 and 2009 will be linked and de-identified within each region. The resulting linked data sets will be quality assured, recoded, harmonised and then pooled into one data set. Analysis of the combined data set will include: frequencies/proportions of congenital anomalies and outcomes (type of CP, severity, impairments); descriptive analyses comparing timing of congenital anomaly development and brain injury/abnormality responsible for CP; ORs to calculate the odds of CP following a specific congenital anomaly; and identification of anomalies on causal pathways to CP.

ETHICS AND DISSEMINATION

Ethics approval for this collaborative study, The Comprehensive CA-CP Study, has been obtained from the Cerebral Palsy Alliance Human Research Ethics Committee (EC00402). Study findings will be disseminated at conferences and published in peer-reviewed journals, and recommendations will be made regarding the collection and classification of congenital anomaly data by CP registers.

Neurologic Correlates of Gait Abnormalities in Cerebral Palsy: Implications for Treatment

Cerebral palsy (CP) is the most common movement disorder in children. A diagnosis of CP is often made based on abnormal muscle tone or posture, a delay in reaching motor milestones, or the presence of gait abnormalities in young children. Neuroimaging of high-risk neonates and of children diagnosed with CP have identified patterns of neurologic injury associated with CP, however, the neural underpinnings of common gait abnormalities remain largely uncharacterized. Here, we review the nature of the brain injury in CP, as well as the neuromuscular deficits and subsequent gait abnormalities common among children with CP. We first discuss brain injury in terms of mechanism, pattern, and time of injury during the prenatal, perinatal, or postnatal period in preterm and term-born children. Second, we outline neuromuscular deficits of CP with a focus on spastic CP, characterized by muscle weakness, shortened muscle-tendon unit, spasticity, and impaired selective motor control, on both a microscopic and functional level. Third, we examine the influence of neuromuscular deficits on gait abnormalities in CP, while considering emerging information on neural correlates of gait abnormalities and the implications for strategic treatment. This review of the neural basis of gait abnormalities in CP discusses what is known about links between the location and extent of brain injury and the type and severity of CP, in relation to the associated neuromuscular deficits, and subsequent gait abnormalities. Targeted treatment opportunities are identified that may improve functional outcomes for children with CP. By providing this context on the neural basis of gait abnormalities in CP, we hope to highlight areas of further research that can reduce the long-term, debilitating effects of CP.

Maternal residential exposure to agricultural pesticides and birth defects in a 2003 to 2005 North Carolina birth cohort

BACKGROUND

Birth defects are responsible for a large proportion of disability and infant mortality. Exposure to a variety of pesticides have been linked to increased risk of birth defects.

METHODS

We conducted a case-control study to estimate the associations between a residence-based metric of agricultural pesticide exposure and birth defects. We linked singleton live birth records for 2003 to 2005 from the North Carolina (NC) State Center for Health Statistics to data from the NC Birth Defects Monitoring Program. Included women had residence at delivery inside NC and infants with gestational ages from 20 to 44 weeks (n = 304,906). Pesticide exposure was assigned using a previously constructed metric, estimating total chemical exposure (pounds of active ingredient) based on crops within 500 meters of maternal residence, specific dates of pregnancy, and chemical application dates based on the planting/harvesting dates of each crop. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals for four categories of exposure (<10(th) , 10-50(th) , 50-90(th) , and >90(th) percentiles) compared with unexposed. Models were adjusted for maternal race, age at delivery, education, marital status, and smoking status.

RESULTS

We observed elevated ORs for congenital heart defects and certain structural defects affecting the gastrointestinal, genitourinary and musculoskeletal systems (e.g., OR [95% confidence interval] [highest exposure vs. unexposed] for tracheal esophageal fistula/esophageal atresia = 1.98 [0.69, 5.66], and OR for atrial septal defects: 1.70 [1.34, 2.14]).

CONCLUSION

Our results provide some evidence of associations between residential exposure to agricultural pesticides and several birth defects phenotypes. Birth Defects Research (Part A) 106:240-249, 2016. © 2016 Wiley Periodicals, Inc.

Congenital Heart Defects and Receipt of Special Education Services

BACKGROUND

We investigated the prevalence of receipt of special education services among children with congenital heart defects (CHDs) compared with children without birth defects.

METHODS

Children born from 1982 to 2004 in metropolitan Atlanta with CHDs (n = 3744) were identified from a population-based birth defect surveillance program; children without birth defects (n = 860 715) were identified from birth certificates. Cohorts were linked to special education files for the 1992-2012 school years to identify special education services. Children with noncardiac defects or genetic syndromes were excluded; children with CHDs were classified by presence or absence of critical CHDs (ie, CHDs requiring intervention by age one year). We evaluated the prevalence of receipt of special education services and prevalence rate ratios using children without birth defects as a reference.

RESULTS

Compared with children without birth defects, children with CHDs were 50% more likely to receive special education services overall (adjusted prevalence rate ratio [aPRR] = 1.5; 95% confidence interval [CI]: 1.4-1.7). Specifically, they had higher prevalence of several special education categories including: intellectual disability (aPRR = 3.8; 95% CI: 2.8-5.1), sensory impairment (aPRR = 3.0; 95% CI: 1.8-5.0), other health impairment (aPRR = 2.8; 95% CI: 2.2-3.5), significant developmental delay (aPRR = 1.9; 95% CI: 1.3-2.8), and specific learning disability (aPRR = 1.4; 95% CI: 1.1-1.7). For most special education services, the excess prevalence did not vary by presence of critical CHDs.

CONCLUSIONS

Children with CHDs received special education services more often than children without birth defects. These findings highlight the need for special education services and the importance of developmental screening for all children with CHDs.

Developmental neurotoxicity - challenges in the 21st century and in vitro opportunities

In recent years neurodevelopmental problems in children have increased at a rate that suggests lifestyle factors and chemical exposures as likely contributors. When environmental chemicals contribute to neurodevelopmental disorders developmental neurotoxicity (DNT) becomes an enormous concern. But how can it be tackled? Current animal test- based guidelines are prohibitively expensive, at $ 1.4 million per substance, while their predictivity for human health effects may be limited, and mechanistic data that would help species extrapolation are not available. A broader screening for substances of concern requires a reliable testing strategy, applicable to larger numbers of substances, and sufficiently predictive to warrant further testing. This review discusses the evidence for possible contributions of environmental chemicals to DNT, limitations of the current test paradigm, emerging concepts and technologies pertinent to in vitro DNT testing and assay evaluation, as well as the prospect of a paradigm shift based on 21st century technologies.

The association between race/ethnicity and major birth defects in the United States, 1999-2007

OBJECTIVES

We investigated the relationship between race/ethnicity and 27 major birth defects.

METHODS

We pooled data from 12 population-based birth defects surveillance systems in the United States that included 13.5 million live births (1 of 3 of US births) from 1999 to 2007. Using Poisson regression, we calculated prevalence estimates for each birth defect and 13 racial/ethnic groupings, along with crude and adjusted prevalence ratios (aPRs). Non-Hispanic Whites served as the referent group.

RESULTS

American Indians/Alaska Natives had a significantly higher and 50% or greater prevalence for 7 conditions (aPR = 3.97; 95% confidence interval [CI] = 2.89, 5.44 for anotia or microtia); aPRs of 1.5 to 2.1 for cleft lip, trisomy 18, and encephalocele, and lower, upper, and any limb deficiency). Cubans and Asians, especially Chinese and Asian Indians, had either significantly lower or similar prevalences of these defects compared with non-Hispanic Whites, with the exception of anotia or microtia among Chinese (aPR = 2.08; 95% CI = 1.30, 3.33) and Filipinos (aPR = 1.90; 95% CI = 1.10, 3.30) and tetralogy of Fallot among Vietnamese (aPR = 1.60; 95% CI = 1.11, 2.32).

CONCLUSIONS

This is the largest population-based study to our knowledge to systematically examine the prevalence of a range of major birth defects across many racial/ethnic groups, including Asian and Hispanic subgroups. The relatively high prevalence of birth defects in American Indians/Alaska Natives warrants further attention.

Validation and quality control of replacement alternatives – current status and future challenges

Alternatives to animal testing have been developed mainly in the fields of toxicology and vaccine testing. Typical examples are the evaluation of phototoxicity, eye irritation or skin corrosion/irritation of cosmetics and industrial chemicals. However, examples can also be found in other biomedical areas, such the control of the quality of drug preparations for pyrogens or for the control of the production process of biologics, such as botulinum neurotoxin. For regulatory purposes, the quality, transferability and predictivity of an alternative method needs to be evaluated. This procedure is called the “validation process” of a new method. It follows defined rules, and several governmental institutions have been established to perform, supervise or advise on this process. As this often results in a delay of method implementation, different alternatives for the evaluation of a method's suitability and quality are under discussion. We describe here the principles of model development and quality control. We also give an overview on methods that have undergone validation. Strengths and shortcomings of traditional approaches are discussed, and new developments and challenges are outlined.

Use of special education services among children with and without congenital gastrointestinal anomalies

Our objective was to evaluate the relationship between congenital gastrointestinal anomalies requiring neonatal surgery and neurodevelopmental outcome. Among the children born in metropolitan Atlanta during 1982-2001 who survived to age 1 year (N = 762,824), we identified children with congenital gastrointestinal anomalies via linkage with the Metropolitan Atlanta Congenital Defects Program and children who received special education services via linkage with the Special Education Database of Metropolitan Atlanta. Several modest increases in special education service use were observed among children with isolated congenital gastrointestinal anomalies; no association was statistically significant. Among children with Hirschsprung disease, gastroschisis, esophageal atresia, intestinal malrotation, bowel atresia, or imperforate anus who had multiple anomalies, we observed statistically significant increases in special education service use.

The co-occurrence of autism and birth defects: prevalence and risk in a population-based cohort

AIM

To estimate the prevalence of major birth defects among children with autism, the prevalence of autism in children with birth defects, and the risk for autism associated with having birth defects.

METHOD

Retrospective cohort including all children born in Atlanta, GA, USA, 1986 to 1993, who survived to age 3 years and were identified through Georgia vital records. Children with autism and other developmental disabilities residing in Atlanta at ages 3 to 10 years in 1996 were identified through the Metropolitan Atlanta Developmental Disabilities Surveillance Program. Children with major birth defects through age 6 years were identified by the Metropolitan Atlanta Congenital Defects Program.

RESULTS

Birth defects were found among 6% of children with autism (total n=617; 488 males, 129 females) and was associated with a near twofold increased risk for autism overall. However, the risk magnitude and statistical significance varied by type of birth defect. With any type of birth defect, the risk for autism accompanied by intellectual disability or other developmental disabilities was typically higher than the risk for autism alone. A 6:1 to 8:1 male bias was observed among children with autism and a birth defect.

INTERPRETATION

Investigation of the association between autism and birth defects is warranted, especially for the role of birth defects in autism among sex-specific or autism subgroups.

Low Apgar score without acidosis may indicate neuromuscular disorder

OBJECTIVE

We hypothesized that in term infants low Apgar score with normal umbilical artery pH (UApH) indicates prenatal damage to the neuromuscular system.

STUDY DESIGN

Retrospective database search of 42,117 liveborn infants born 1993-2005. Medical record analysis of 3104 term infants with cardiorespiratory maladaptation referred for special neonatal care. Focus on infants with UApH >7.00 and 5-min Apgar <6 (group A, n=74), UApH <7.00 and 5-min Apgar >5 (group B, n=49), and UApH <7.00 and 5-min Apgar <6 (group C, n=14).

RESULTS

Incidence of 5-min Apgar score <6 was 0.50% in term infants. Mean (SD) UApH was 7.262 (0.075, P=0.075); incidence of UApH <7.00 was 0.30% in term infants. Nucleated red blood cells were elevated without differences in all three groups. Parental consanguinity was present in 39 of the 137 maladapted infants. In groups A/B/C, 10/18/2 infants were small for gestational age (P=0.002 for A vs B) and in 16/1/0 neuromuscular anomalies were identified (P=0.004 for A vs B). Eight of the 17 anomalies had been suspected prenatally. Logistic regression proved neuromuscular disorder the only independent variable discriminating between groups A and B.

CONCLUSIONS

Neuromuscular problems are the cause rather than the result of maladaptation. For unexplained low Apgar score, especially without acidosis, meticulous examination of the infant including brain imaging and EEG is justified.

Cerebral palsy and congenital malformations

AIM

To determine the proportion of children with cerebral palsy (CP) who have cerebral and non-cerebral congenital malformations.

METHODS

Data from 11 CP registries contributing to the European Cerebral Palsy Database (SCPE), for children born in the period 1976-1996. The malformations were classified as recognized syndromes, chromosomal anomalies, cerebral malformations or non-cerebral malformations. Prevalence of malformations was compared to published data on livebirths from a European database of congenital malformations (EUROCAT).

RESULTS

Overall 547 out of 4584 children (11.9%) with CP were reported to have a congenital malformation. The majority (8.6% of all children) were diagnosed with a cerebral malformation. The most frequent types of cerebral malformations were microcephaly and hydrocephaly. Non-cerebral malformations were present in 97 CP children and in further 14 CP children with cerebral malformations. The most frequent groups of non-cerebral malformations were cardiac, facial clefts and limb and skeleton malformations. Children born at term had a significantly higher prevalence of cerebral malformations compared to children born before 32 weeks (12.1% versus 2.1%, p<0.001).

CONCLUSION

Cerebral malformations were much more frequent among children with CP than among all livebirths in the population. Malformations in organ systems close to the brain (eye, facial clefts) were more frequent in the CP population while malformations in organ systems further from the brain (renal, genital) were more frequent in the general population.

Is cerebral palsy associated with birth defects other than cerebral defects?

The objective of the study was to identify the origin (s) of the association between cerebral palsy (CP) and birth defects in the absence of cerebral birth defects. Data from the 1980 to 1994 Western Australian birth cohorts (355 659 neonatal survivors) were linked to the Cerebral Palsy Register (941 links) and the Birth Defects Registry (17070 links). Associations between CP (congenital or acquired) and birth defects (cerebral or exclusively non-cerebral) were estimated. The origin of the association between non-cerebral defects and acquired CP was investigated with an observational study, and the origin of the association between non-cerebral defects and congenital CP was investigated with a blinded case-control study of births with non-cerebral defects with or without CP. With non-cerebral defects, the odds ratio for CP was 4.8 (95% CI 3.1-7.4) if acquired and 4.7 (3.9-5.7) if congenital. For acquired CP, the association arose primarily as a result of cardiac defects. For congenital CP, the association arose partly from ascertainment bias and partly from defects known to be associated with cerebral defects (but not identified in these data). However, a significant portion remained unexplained. The presence of non-cerebral defects should heighten clinical alertness to the possibility of CP and of cerebral birth defects.

Co-occurrence of birth defects and intellectual disability

This study used population-based databases to ascertain birth defects and intellectual disability (ID), defined as full IQ < 70, in children born in Western Australia during 1980-99. Of the children surviving to 1 year (n = 474 285), 4.9% had birth defects and 1.3% ID. ID was identified in 7.9% of children with birth defects. After adjusting for sex, mother's age, race, parity, plurality, birthweight and gestational age the prevalence ratio (PR) [95% confidence interval (CI)] for ID in children with birth defects compared with those with no birth defects was 7.6 [7.2, 8.0]. Those with chromosomal anomalies comprised 3.2% of the group with birth defects. The percentage ID (and PR [95% CI]) in specific categories were: Down's syndrome 97% (84.5 [79.4, 90.0]), sex chromosome anomalies 30.3% (31.0 [23.8, 40.3]), other chromosomal anomalies 64.2% (54.2 [47.2, 62.3]). Birth defects were categorised according to system in the 96.8% of children with non-chromosomal anomalies. The percentage with ID (and PR [95% CI]) for birth defects in each system were: spina bifida 18.8 (16.7 [12.2, 23.0]); nervous (except spina bifida) 38.6 (33.4 [30.3, 36.9]); cardiovascular 4.2 (4.1 [3.5, 4.8]); gastro-intestinal 2.2 (2.0 [1.5, 2.7]); urogenital 2.6 (2.4 [2.0, 2.8]; musculo-skeletal 3.6 (4.0 [3.5, 4.6]); other non-chromosomal 7.0 (7.3 [6.5, 8.3]); and multiple systems 12.3 (10.2 [8.6, 12.2]). Birth defects were present in 30.2% of children with ID (27.7% of children with mild/moderate ID (IQ 40-69) and 54% of children with severe ID (IQ < 40)). Adjusted PRs for birth defects in children with any ID, mild/moderate ID and severe ID compared with children with normal intellectual function were 6.0 [5.8, 6.3], 5.5 [5.3, 5.8] and 10.5 [9.7, 11.4] respectively. The data are useful for those providing services for children with developmental disabilities especially for predicting family support and respite and accommodation requirements for children and adults with severe ID.

Infant C677TMTHFR 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. DNA was extracted from newborn screening filter papers. Cases and controls were genotyped TT if homozygous for the MTHFR C677T allele, CT if heterozygous for the C677T allele, and CC if homozygous for the C677 (wild type) allele.

RESULTS

Overall, case and control infants had similar percentages of TT and CT genotypes. Percentages between cases and controls differed somewhat across race/ethnic groups. Elevated ORs of 1.9 (95% CI: 0.7-5.0) and 2.6 (95% CI: 1.1-5.8) were observed for the TT and CT genotypes, respectively, among Hispanic children. Observed results were not substantially altered for analyses that removed 41 case children who also had structural birth defects.

CONCLUSIONS

Folate-related mechanisms are important to investigate for etiologies of birth defects, and such lines of inquiry may be revealing for mental retardation given the relationships between mental retardation and birth defects and potential relationships between folate, DNA methylation, and mental retardation.

Medidas psicofísicas e eletrofisiológicas da função visual do recém nascido: uma revisão

O sistema visual apresenta muitas funções ao nascimento. O processo de amadurecimento destas funções demanda um tempo variado. Neste trabalho, inicialmente descreveremos como a psicofísica e a eletrofisiologia visual tem colaborado para a medida e o estudo do desenvolvimento de três funções visuais: acuidade visual, sensibilidade ao contraste e visão de cores. Num segundo momento, discutimos sobre como a medida e o desenvolvimento destas funções podem estar prejudicados em patologias que afetam o sistema visual, como a prematuridade e a paralisia cerebral.

A population-based study of the recurrence of developmental disabilities--Metropolitan Atlanta Developmental Disabilities Surveillance Program, 1991-94

Serious developmental disabilities (DD) are quite common and affect approximately 2% of all school-aged children. The impact of DDs with respect to the need for special education services, medical care and the demand on family members can be enormous. While this impact can be magnified for families with more than one child with a DD, little is known regarding the epidemiology of recurrence of DDs. When the cause of a DD is unknown, genetic counsellors rely on recurrence risk estimates which for DDs are over 10 years old. The objectives of our study were to: (1) assess the contribution of recurrent cases to the prevalence of DDs; (2) provide current, population-based recurrence risk estimates; and (3) examine characteristics of the first affected child as predictors of recurrence. Two population-based data sources were used to identify all children born to the same mother during the period 1981-91 in the five-county metropolitan Atlanta area with at least one of four DDs: mental retardation (MR), cerebral palsy, hearing loss, or vision impairment. Recurrence risk estimates for these DDs ranged from 3% to 7% and were many times higher than the background prevalences. The risk of recurrence of DDs was greatest for MR - approximately eight times greater than the baseline MR prevalence. Isolated mild MR (IQ 50-70) was highly concordant between siblings with MR. Sex, race, and birthweight of the index child, maternal education, and maternal age were not significantly associated with recurrence risk. Further research is needed to investigate the roles of genetic and environmental factors on the recurrence of DDs, particularly isolated mild MR.

Genetic syndromes among individuals with mental retardation

Individuals with mental retardation more commonly have malformations and other structural anomalies than individuals without mental retardation. In many cases, the associated anomalies comprise recognizable syndromes caused by genetic or environmental insults. To co-occurrence of structural anomalies with mental retardation thus assists in the diagnostic evaluation, particularly in infants and young children. The coexistence of structural and mental abnormalities also suggests that both originated in the embryonic period of development.

Antenatal risk factors for cerebral palsy

Two of every 1000 live-born children develop cerebral palsy (CP). The aetiology of CP is often unclear and because CP is a symptom complex rather than a disease, clinically defined at 4-5 years of age, it is not surprising that there are considerable problems associated with epidemiological studies of its aetiology. The only reason for the CP concept is that it emanates from an insult to a growing, developing brain and a dynamic clinical picture from static pathology. Evidence suggests that 70-80% of CP cases are due to prenatal factors and that birth asphyxia plays a relatively minor role (<10%). Some antenatal risk factors are repeatedly observed to be related to CP: low gestational age, male gender, multiple gestation, intrauterine viral infections and maternal thyroid abnormalities. Recently, intrauterine infection/inflammation with a maternal response (consisting of chorioamnionitis) and a fetal inflammatory response (consisting of funicitis or elevated interleukin-6 in fetal plasma) has been found to be related to white matter injury and CP. Some risk factors are associated with CP at all gestational ages whereas others mostly affect term or preterm infants, e.g. intrauterine growth restriction seems to be a risk factor in term infants. There also seems to be an association between autoimmune and coagulation disorders and CP.

Co-occurrence of developmental disabilities with birth defects

This article begins with a discussion of the concepts of comorbidity and co-occurrence of diseases and health conditions. These concepts are then applied to the literature on the population-based prevalence of developmental disabilities and birth defects. Most of the existing literature focuses on co-occurrence and obtains data from both clinical and administrative sources. Developmental disabilities occur more frequently in children with multiple, rather than with isolated, birth defects. More research, with more sophisticated study designs, will be necessary to further elucidate the contributions of birth defects to the etiology of developmental disabilities, control for other risk factors, and to identify strategies for prevention and intervention services.

The epidemiology of cerebral palsy in term infants

Half of cerebral palsy (CP) arises in infants of normal birthweight; yet, many fewer studies seek to identify risk factors for CP in term and near-term infants than in those born very prematurely. There has been no net decrease in the prevalence of CP in term and near-term infants over recent decades. Potentially asphyxiating birth complications account for a small minority of CP cases. Recent studies suggest that disorders of coagulation and intrauterine exposure to infection or inflammation are associated with risk of CP, and that both can be accompanied by signs of neonatal encephalopathy, the best available predictor of CP in term neonates. Therapeutic interventions directed at preventing interruption of oxygen supply have not been shown to reduce the occurrence of CP. There have not yet been studies examining whether medical interventions directed at infection or coagulation disorder can reduce the frequency of CP.