The role of maternal reproductive history in the aetiology of neural tube defects

Variants in MTHFR gene and neural tube defects susceptibility in China

Neural tube defect (NTD) is a severe congenital birth abnormalities involving incomplete neural tube closure. 5, 10-methylenetetrahydrofolate reductase (MTHFR) gene plays key role in folate cycle and methylation cycle, which could affect the DNA synthesis, repair and methylation. In this study, we aim to investigate the correlation between MTHFR polymorphisms and NTD-affected pregnancy. There were 444 participants involved in our study. Tag-SNPs were identified in HapMap Databases. Blood samples were collected from all subjects to further extract the genomic DNAs by TaqMan Blood DNA kits. We also carried out a meta-analysis based on previous published studies to further examine the association between MTHFR polymorphisms and NTD. In case-control study analysis, two SNPs were identified to be associated with NTD risk. The 677 C > T genetic variant was correlated with increased risk of NTD-affected pregnancy. However, the 1298 A > C polymorphism was shown to lower the risk of NTD-affected pregnancy. The protective role of 1298 A > C polymorphisms was further supported by the result of meta-analysis. Our study revealed that the SNPs of 677C > T and 1298A > C in MTHFR were associated with NTD-affected pregnancy, in which 677C > T was a risk factor and in contrast 1298A > C was protective factor against NTD. Our results of meta-analysis also revealed the 1298A > C MTHFR polymorphism play protective role in NTD.

Maternal reproductive history and the risk of congenital heart defects in offspring: a systematic review and meta-analysis

Epidemiological studies have reported conflicting results on the association of congenital heart defect (CHD) risk in offspring with a maternal history of prior pregnancies and abortions, but no meta-analysis has been reported. We searched MEDLINE and EMBASE from their inception to April 14, 2014, for relevant studies that assessed the association between maternal reproductive history and CHD risk. Two authors independently assessed eligibility and extracted data. Fixed-effects or random-effects models were used to calculate the pooled odds ratios (ORs). Among 1,599 references, 17 case-control studies and one nested case-control study were included in this meta-analysis. The summary OR for the ever versus nulligravidity was 1.18 (95% CI 1.03-1.34). A dose-response analysis also indicated a positive effect of maternal gravidity on CHD risk, and the summary OR for each increment in number of pregnancies was 1.13 (95% CI 1.08-1.18). A history of abortion was associated with a 24% higher risk of CHD, OR = 1.24 (95% CI 1.11-1.38). When stratified by abortion category, CHD risk increased by 18 and 58% with a history of spontaneous abortion and induced abortion, respectively. The summary OR for each increment of one abortion was 1.28 (95% CI 1.18-1.40). In summary, this study provides evidence that increased maternal gravidity was positively associated with a risk of CHDs in offspring. Meanwhile, our results demonstrate a positive association of any history of abortion with an increased risk of CHDs.

Is Gravidity 4+ a Risk Factor for Oral Clefts? A Case-Control Study in Eight South American Countries Using Structural Equation Modeling

Background

There is disagreement about the association between cleft lip with or without cleft palate and multigravidity, which could be explained by differences of adjusting for maternal age, Amerindian ancestry, and socioeconomic status.

Objective

The aim was to evaluate gravidity 4+ (four or more gestations) as a risk factor for cleft lip with or without cleft palate in South America.

Design

We used a matched (1:1) case-control study with structural equation modeling for related causes. Data were obtained from 1,371,575 consecutive newborn infants weighing ≥500 g who were born in the hospitals of the Estudio Colaborativo Latinoamericano de Malformaciones Congénitas (ECLAMC) network between 1982 and 1999. There were a total of 1,271 cases with cleft lip with or without cleft palate (excluding midline and atypical cleft lip with or without cleft palate). A total of 1,227 case-control pairs were obtained, matched by maternal age, newborn gender, and year and place of birth. Potential confounders and intermediary variables were analyzed with structural equation modeling.

Results

The crude risk of gravidity 4+ was 1.41 and the 95% confidence interval was 1.14 to 1.61. When applying structural equation modeling, the effect of multigravidity on the risk of cleft lip with or without cleft palate was 1.22 and the 95% confidence interval was 0.91 to 1.39.

Conclusions

Multigravid mothers (more than four gestations) showed no greater risk of bearing children who had cleft lip with or without cleft palate than mothers with two or three births. Therefore, the often observed and reported association between multigravidity and oral clefts likely reflects the effect of other risk factors related to low socioeconomic status in South American populations.

A cost-of-illness study of spina bifida in Italy

Introduction

Spina bifida (SB) is a congenital malformation of the spinal cord, nerves, and adjacent covering structures, with different levels of severity and functional disability. The economic cost of spina bifida and its prevention using folic acid have never been estimated in Italy. This study was conducted to define the cost of illness of SB in Italy.

Methods

A retrospective multicenter observational study on the social cost of patients with SB was carried out in three SB centers in Italy. Cost data were collected relating to the 12 months preceding the enrollment time (T0), and subsequently 3 months after the T0 time (±20 days) through a case report form designed to collect the relevant information on the costs incurred during the period considered. The data for all patients were analyzed through multivariate analysis on the main parameters.

Results

We enrolled 128 patients equally divided between males and females, with a mean age of 13 years (minimum, 0; maximum, 29). Diagnosis was mostly postnatal, with 64 cases diagnosed at birth and 33 cases diagnosed subsequently. The lesion severity levels, as defined in the inclusion criteria, were walking (52 patients); walking with simple orthoses (33 patients); walking with complex orthoses (16 patients); and nonwalking, (25 patients). The anatomic type identified is open SB in most cases (84 patients), followed by closed SB (37 patients) and SB occulta (3 patients). The most significant cost per year was for assistive devices, for a total of 4307.00 €, followed by hospitalization (907.00 €), examinations (592.00 €), and drug therapy (328.00 €). Cost breakdown by age range shows that the highest costs are incurred in the 0–4 age range. The highest cost was for cases of open SB (12,103.00 €). The cost/degree of severity ratio showed that the highest cost was for nonwalking patients (14,323.00 €), followed by patients walking with complex orthoses (13,799.00 €).

Conclusion

The data from this study show that the mean total cost for a patient with SB was 11,351.00 € per year. Based on data provided by the Italian Institute of Health, we can estimate a total annual social cost of about 60 million Euros per year for SB in Italy. Cost of illness was correlated with age and degree of severity of SB.

Maternal reproductive history and the risk of isolated congenital malformations

We examined the relationship between maternal reproductive history and the newborn's risk of isolated congenital malformations in a large case-control cohort from the Polish Registry of Congenital Malformations. Congenital malformations were classified into four categories: isolated congenital heart defects (n=1673), isolated cleft palate (n=255), cleft lip with or without cleft palate (n=448) and renal agenesis (n=103). The case groups were compared with a shared group of 2068 controls recruited in the same time period and geographic area. Multivariable logistic regression was used to assess the risk associated with maternal gravidity and of previous miscarriages after accounting for maternal age and other potential risk factors. In unadjusted analyses, maternal gravidity was significantly associated with increased risk of all four classes of congenital malformations. After adjustment, a significant association persisted for congenital heart defects [odds ratio (OR)=1.22, [95% confidence interval (CI) 1.09, 1.36], P=0.0007] and cleft lip with or without cleft palate (OR=1.21, [95% CI 1.09, 1.36], P=0.0005). A similar trend existed for isolated cleft palate (OR=1.18, [95% CI 1.02, 1.37], P=0.03). There was no appreciable increase in the risk of congenital malformations associated with a maternal history of miscarriages, but a trend for a protective effect on the occurrence of cleft lip with or without cleft palate was observed (OR=0.72, [95% CI 0.52, 0.99], P=0.045). Based on our data, maternal gravidity represents a significant risk factor for congenital heart defects and cleft lip with or without cleft palate in the newborn infant. Our data do not support an increase in risk because of past history of miscarriages.

Weekly Administration of Folic Acid and Epidemiology of Neural Tube Defects

OBJECTIVE

In 1999, a folic acid campaign for prevention of neural tube defects was started in Nuevo León, México, with the recommendation of taking a 5000 -mcg tablet of folic acid per week. The purpose of this study was to compare the epidemiology of neural tube defects after four years of the campaign.

METHODS

Cases of anencephaly, spina bifida, and encephalocele (ICD Q00, Q01, Q05, 10th Ed.) from public and private hospitals were registered by immediate notification, death certificates, and fetal death registries. Comparisons of neural tube defects rates, phenotype distribution of cases, and sex ratios, registered before and after the folic acid campaign, were done using the Student's t Test and Chi square test.

RESULTS

There was a 50% reduction in the incidence of anencephaly and spina bifida cases from 93 in 1999 (1.04x1000) to 46 in the year 2003 (0.56x1000) (p<0.001). Spina bifida cases declined up to 70% in 2002 and anencephaly cases up to 50% in 2003. In 1999, overall, the ratio (females: males) was 0.66 with female excess; the sex ratio was similar for anencephaly and spina bifida cases. In the year 2000, female cases showed a significant reduction for both spina bifida and anencephaly (75% and 56% respectively); the sex ratio was 0.57 with a greater male excess for both phenotypes.

CONCLUSIONS

Weekly administration of 5000 mcg of folic acid reduces the incidence of neural tube defects 50%, primarily spina bifida, with a higher reduction of female cases.

A reproductive history of mothers with spina bifida offspring--a new look at old issues

Background

Spina bifida is a disorder of the cerebrospinal fluid system associated with failure of neural tube closure in the fetus. Reproductive history studies of mothers with spina bifida offspring have often been conducted shortly after the affected child's birth. In this study, a large group of community-based mothers were studied after most had completed their families. The aims were to present a more comprehensive reproductive history and to test several hypotheses regarding the nature of spina bifida.

Methods

Data from 271 mothers was collected by interview 18.3 mean years after the affected child's birth. Data analysis was by χ-square, Fisher exact test and t test with a p value less than 0.05 considered significant.

Results

Females made up 56.5% of affected offspring (probands) and 53.1% of unaffected offspring. The spina bifida and anencephaly recurrence rate was 4.0%. The twinning rate was 8.6/1000 live births. 24.4% of mothers had a history of spontaneous abortion and the rate varied by pregnancy order from 87 to 185/1000 live births. Duration of pregnancies subsequent to probands was shorter for female than male probands. Mean birth weight of probands with high lesions exceeded those with low lesions. A spontaneous abortion preceded female probands more often than males as compared to live births. Affected males with high lesions conceived by white mothers were at greater risk to be spontaneously aborted. Previous inter-gestational interval for mothers with no history of spontaneous abortion was longer for probands than unaffected offspring but not for mothers with a history of spontaneous abortion.

Conclusion

Overall, and for every major subgroup of these mothers, more affected and unaffected female than male offspring were born. Differences by gender and lesion level among probands and between probands and unaffected offspring were consistent with an etiology of unknown genetic factors, hormonal and/or immune system factors.

Maternal miscarriage history and risk of anencephaly

Women with a history of reproductive loss may be at an increased risk of having an unfavourable outcome in subsequent pregnancies. Using data from a matched case-control study based on the record of the Epidemiological Surveillance System of Neural Tube Defects, we evaluated the association between history of maternal reproductive loss and the risk of anencephaly in three Mexican states. Mothers of 157 cases of anencephaly and 151 controls born during the period March 2000 to February 2001, were interviewed about their reproductive history and other additional factors, including socio-economic characteristics, prenatal care, use of tobacco and alcohol, presence of chronic diseases, acute illnesses and fever during the periconceptional period, and consumption of multivitamins and medicines during this period; mothers who reported no prior pregnancies were excluded from the analysis; 58 matched case-control pairs were used for the analysis. After adjusting for potential confounders, women with a history of miscarriage in previous pregnancies had 4.58 times more risk of having a child with anencephaly, than those who did not have this history; OR = 4.58, [95% CI 1.22, 17.23]. Our results suggest that a history of previous miscarriages is a risk indicator for anencephaly in future gestations. This does not necessarily mean that the miscarriage itself is the cause, but that common mechanisms could be involved in the aetiology of both events. Thus, women who have had histories of reproductive losses, especially miscarriages, should be a priority group for the primary and secondary prevention of neural tube defects.