Prevention of neural tube defects: Results of the Medical Research Council vitamin study

Objective To estimate the current incidence and prevalence in the United States of 12 neurologic disorders. Methods We summarize the strongest evidence available, using data from the United States or from other developed countries when US data were insufficient. Results For some disorders, prevalence is a better descriptor of impact; for others, incidence is preferable. Per 1,000 children, estimated prevalence was 5.8 for autism spectrum disorder and 2.4 for cerebral palsy; for Tourette syndrome, the data were insufficient. In the general population, per 1,000, the 1-year prevalence for migraine was 121, 7.1 for epilepsy, and 0.9 for multiple sclerosis. Among the elderly, the prevalence of Alzheimer disease was 67 and that of Parkinson disease was 9.5. For diseases best described by annual incidence per 100,000, the rate for stroke was 183, 101 for major traumatic brain injury, 4.5 for spinal cord injury, and 1.6 for ALS. Conclusions Using the best available data, our survey of a limited number of disorders shows that the burden of neurologic illness affects many millions of people in the United States.

How common are the “common” neurologic disorders?

Background Periconceptional use of multivitamins containing folic acid can reduce a woman's risk of having a baby with a neural-tube defect. Methods As part of a public health campaign conducted from 1993 to 1995 in an area of China with high rates of neural-tube defects (the northern region) and one with low rates (the southern region), we evaluated the outcomes of pregnancy in women who were asked to take a pill containing 400 μg of folic acid alone daily from the time of their premarital examination until the end of their first trimester of pregnancy. Results Among the fetuses or infants of 130,142 women who took folic acid at any time before or during pregnancy and 117,689 women who had not taken folic acid, we identified 102 and 173, respectively, with neural-tube defects. Among the fetuses or infants of women who registered before their last menstrual period and who did not take any folic acid, the rates of neural-tube defects were 4.8 per 1000 pregnancies of at least 20 weeks' gestation in the nort...

https://www.nejm.org/doi/pdf/10.1056/NEJM199911113412001

Prevention of Neural-Tube Defects with Folic Acid in China

Background In 1996, the Food and Drug Administration issued a regulation requiring all enriched grain products to be fortified with folic acid to reduce the risk of neural-tube defects in newborns. Fortification (140 μg per 100 g) began in 1996, and the process was essentially complete by mid-1997. Methods To assess the effect of folic acid fortification on folate status, we measured plasma folate and total homocysteine concentrations (a sensitive marker of folate status) using blood samples from the fifth examination (January 1991 to December 1994) of the Framingham Offspring Study cohort for base-line values and the sixth examination (January 1995 to August 1998) for follow-up values. We divided the cohort into two groups on the basis of the date of their follow-up examination: the study group consisted of 350 subjects who were seen after fortification (September 1997 to March 1998), and the control group consisted of 756 subjects who were seen before fortification (January 1995 to September 1996). Resu...

https://www.nejm.org/doi/pdf/10.1056/NEJM199905133401901

The Effect of Folic Acid Fortification on Plasma Folate and Total Homocysteine Concentrations

Objective To compare the perinatal outcome of singleton and twin pregnancies between natural and assisted conceptions. Design Systematic review of controlled studies published 1985-2002. Studies reviewed 25 studies were included of which 17 had matched and 8 had non-matched controls. Main outcome measures Very preterm birth, preterm birth, very low birth weight, low birth weight, small for gestational age, caesarean section, admission to neonatal intensive care unit, and perinatal mortality. Results For singletons, studies with matched controls indicated a relative risk of 3.27 (95% confidence interval 2.03 to 5.28) for very preterm ( < 32 weeks) and 2.04 (1.80 to 2.32) for preterm ( < 37 weeks) birth in pregnancies after assisted conception. Relative risks were 3.00 (2.07 to 4.36) for very low birth weight ( < 1500 g), 1.70 (1.50 to 1.92) for low birth weight ( < 2500 g), 1.40 (1.15 to 1.71) for small for gestational age, 1.54 (1.44 to 1.66) for caesarean section, 1.27 (1.16 to 1.40) for admission to a neonatal intensive care unit, and 1.68 (1.11 to 2.55) for perinatal mortality. Results of the non-matched studies were similar. In matched studies of twin gestations, relative risks were 0.95 (0.78 to 1.15) for very preterm birth, 1.07 (1.02 to 1.13) for preterm birth, 0.89 (0.74 to 1.07) for very low birth weight, 1.03 (0.99 to 1.08) for low birth weight, 1.27 (0.97 to 1.65) for small for gestational age, 1.21 (1.11 to 1.32) for caesarean section, 1.05 (1.01 to 1.09) for admission to a neonatal intensive care unit, and 0.58 (0.44 to 0.77) for perinatal mortality. The non-matched studies mostly showed similar trends. Conclusions Singleton pregnancies from assisted reproduction have a significantly worse perinatal outcome than non-assisted singleton pregnancies, but this is less so for twin pregnancies. In twin pregnancies, perinatal mortality is about 40% lower after assisted compared with natural conception.

https://www.bmj.com/content/bmj/328/7434/261.full.pdf

J. Wild

Papers

Further experience of vitamin supplementation for prevention of neural tube defect recurrences.

Prevention of neural tube defects

Higher multiple births and the modern management of infertility in Britain

Randomised double-blind controlled trial of effect of morphine on catecholamine concentrations in ventilated pre-term babies

Nonenzymatic degradation and salvage of dietary folate: physicochemical factors likely to influence bioavailability.