Teratology Society Consensus Statement on use of folic acid to reduce the risk of birth defects

Maternal Folic Acid Supplementation and the Risk of Oral Clefts in Offspring

INTRODUCTION

There is controversial evidence from the literature regarding the protective effect of folic acid supplementation during pregnancy against orofacial clefts. The authors undertook this meta-analysis to assess whether folate supplementation during pregnancy can reduce the risk of nonsyndromic cleft lip with or without cleft palate (CL/P) and cleft palate only (CPO) in infants.

METHODS

Eligible articles were identified by searching databases, including PubMed, Medline, Scopus, ISI (Web of Knowledge) to September 2017. A meta-analysis was performed to evaluate the effects of maternal supplementation on oral clefts. Odds ratios (ORs) and 95% confidence intervals (CIs) were pooled using Stata software. Publication bias was assessed by the Begg and Egger test. (Registration ID: CRD42018083922) RESULTS:: Out of the 1630 articles found in the authors' initial literature searches, 6 cohort studies, and 31 case-control studies were included in the authors' final meta-analysis. The results of the main analysis revealed that maternal folate supplementation was associated with a modest but statically significant decreased risk of all cleft subtypes (OR = 0.69, 95% CI: 0.60, 0.78). Folic acid intake alone was inversely associated with CL/P (OR = 0.73, 95% CI: 0.62-0.85,) but to a lesser extent than CPO (OR = 0.75, 95% CI = 053-1.04). Multivitamin intake had a significant protective effect for CL/P (OR = 0.65 95% CI = 0.55-0.80) as well as CPO (OR = 0.69, 95% CI = 0.53-0.90).

CONCLUSIONS

Our results indicate that maternal supplementation in early pregnancy reduces the risk of nonsyndromic CL/P and CPO in infants. These data can serve to reassure women planning a pregnancy to consume multivitamins during the periconception period to protect against oral clefts.

Maternal folic acid supplementation and the risk of congenital heart defects in offspring: a meta-analysis of epidemiological observational studies

Epidemiological studies have reported conflicting results regarding the association between maternal folic acid supplementation and the risk of congenital heart defects (CHDs). However, a meta-analysis of the association between maternal folic acid supplementation and CHDs in offspring has not been conducted. We searched the MEDLINE and EMBASE databases for articles cataloged between their inceptions and October 10, 2014 and identified relevant published studies that assessed the association between maternal folate supplementation and the risk of CHDs. Study-specific relative risk estimates were pooled using random-effects or fixed-effects models. Out of the 1,606 articles found in our initial literature searches, a total of 1 randomized controlled trial, 1 cohort study, and 16 case-control studies were included in our final meta-analysis. The overall results of this meta-analysis provide evidence that maternal folate supplementation is associated with a significantly decreased risk of CHDs (RR = 0.72, 95% CI: 0.63–0.82). Statistically significant heterogeneity was detected (Q = 82.48, P < 0.001, I² = 79.4%). We conducted stratified and meta-regression analyses to identify the origin of the heterogeneity among the studies, and a Galbraith plot was generated to graphically assess the sources of heterogeneity. This meta-analysis provides a robust estimate of the positive association between maternal folate supplementation and a decreased risk of CHDs.

Infant mortality and congenital anomalies from 1950 to 1994: an international perspective

STUDY OBJECTIVE

To provide an international perspective on the impact of congenital anomalies on infant mortality from 1950 to 1994.

DESIGN

Population-based study based on data obtained from vital statistics reported to the World Health Organisation.

SETTINGS

36 countries from Europe, the Middle East, the Americas, Asia, and the South Pacific.

RESULTS

On average, infant mortality declined 68.8 per cent from 1950 to 1994. In the countries studied, infant mortality attributable to congenital anomalies decreased by 33.4 per cent, although it recently increased in some countries in Central and Latin America and in Eastern Europe. Anomalies of the heart and of the central nervous system accounted for 48.9 per cent of infant deaths attributable to congenital anomalies. During 1990-1994, infant mortality attributable to congenital anomalies was inversely correlated to the per capita gross domestic product in the countries studied. At the same time, the proportion of infant deaths attributable to congenital malformations was directly correlated with the per capita gross domestic product.

CONCLUSIONS

Congenital malformations account for an increasing proportion of infant deaths in both developed and developing countries. Infant mortality attributable to congenital anomalies is higher in poorer countries although as a proportion of infant deaths it is greater in wealthier countries. Conditions such as spina bifida, whose occurrence can be reduced through preventive strategies, still cause many infant deaths. The apparent increase of infant mortality because of congenital anomalies in some countries should be investigated to confirm the finding, find the causes, and provide prevention opportunities.

Appropriate use of animal models in the assessment of risk during prenatal development: an illustration using inorganic arsenic

BACKGROUND

Assessing risks to human development from chemical exposure typically requires integrating findings from laboratory animal and human studies.

METHODS

Using a case study approach, we present a program designed to assess the risk of the occurrence of malformations from inorganic arsenic exposure. We discuss how epidemiological data should be evaluated for quality and criteria for determining whether an association is causal. In this case study, adequate epidemiological data were not available for evaluating the potential effect of arsenic on development. Consequently, results from appropriately designed, conducted, and interpreted developmental toxicity studies, which have been shown to be predictive of human risk under numerous scenarios, were used. In our case study, the existing animal data were not designed appropriately to assess risk from environmental exposures, although such studies may be useful for hazard identification. Because the human and animal databases were deficient, a research program comprising modern guideline toxicological studies was designed and conducted.

RESULTS

The results of those studies in rats, mice, and rabbits indicate that oral and inhalational exposures to inorganic arsenic do not cause structural malformations, and inhalational exposures produced no developmental effects at all. The new study results are discussed in conjunction with considerations of metabolism, toxicokinetics, and maternal toxicity.

CONCLUSIONS

Based on the available experimental data, and absent contrary findings from adequately conducted epidemiological studies, we conclude that exposure to inorganic arsenic by environmentally relevant routes poses no risk of the occurrence of malformations and little risk of other prenatal developmental toxicity in developing humans without concomitant and near-lethal toxicological effects in mothers.