Prevalence of neural tube defects unchanged over 20 years in Europe


1. The prevalence of non-chromosomal neural tube defects was similar between 1991 to 2011 in 19 European nations.

2. The live birth prevalence of neural tube defects decreased, likely due to increased prenatal testing and termination of subsequent pregnancies positive for fetal anomalies.

Evidence Rating Level: 1 (Excellent)      

Study Rundown: While folic acid supplementation around conception is known to reduce the occurrence of non-chromosomal neural tube defects (NTDs), some studies point to low adherence to this practice in Europe. To determine the prevalence of NTDs in Europe between 1991 and 2011, this study used the central EUROCAT database to document the prevalence of NTDs in 19 European countries over 12.5 million live births. This study did not find an appreciable change in non-chromosomal NTDs over the period study. However, there was a significant decrease in live birth NTD prevalence, likely due to better prenatal screening and subsequent termination of fetuses with detected anomalies.

Due to the vast coverage of potential cases and overall live births, the results are likely to be very  accurate for the 19 European nations these databases cover. However, little can be inferred about any potential link between the unchanging NTD prevalence and changes in folic acid supplementation, as no data measuring folic acid supplementation was presented. Directly linking an unchanged rate of folic acid supplementation and NTD prevalence would be helpful for European lawmakers when deciding to enact mandatory folic acid supplementation policies.

Click to read the study in BMJ

Click to read an accompanying editorial in BMJ

Relevant Reading: Prevention of Neural Tube Defects: A Cross-Sectional Study of the Uptake of Folic Acid Supplementation in Nearly Half a Million Women

In-Depth [retrospective cohort]: More than 11,000 cases of non-chromosomal NTDs out of 12.5 million live births were recorded in the EUROCAT database covering 19 different countries from 1991 to 2011. Over this time, the rate of non-chromosomal NTDs was 9.1 cases per 10,000 births (CI95 8.9 to 9.3). While some fluctuations in this rate occurred over time, they were minor. Specifically, The total prevalence of non-chromosomal NTDs increased by 4% between 1995 to 1999 (CI95 1.01 to 1.07), decreased by 3% between 1999 to 2003 (CI95 0.93 to 0.99), and was stable after that. In contrast, live birth NTDs decreased significantly from 1991 to 1995 by 7% (CI95 0.88 to 0.98). Though non-significant, trends towards decreases in live birth NTD prevalence were seen in the following years.

Image: PD

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