although 5% is the commonly quoted result worldwide) and only a portion of neural tube defects are detected by this screen test (73% in the same ontario study). msafp screening combined with routine ultrasonography has the best detection rate although detection by ultrasonography is dependent on operator training and the quality of the equipment. prevention incidence of neural tube defects has been shown to decline through maintenance of adequate folic acid levels prior to and during pregnancy. this is achieved through dietary sources and supplementation of folic acid. in 1996, the united states food and drug administration published regulations requiring the addition of folic acid to enriched breads, cereals, flour and other grain products. similar regulations made it mandatory to fortify selected grain products with folic acid in canada by 1998. during the first four weeks of pregnancy (when most people do not even realize that they are pregnant), adequate folate intake is essential for proper operation of the neurulation process. therefore, any individuals who could become pregnant are advised to eat foods fortified with folic acid or take supplements in addition to eating folate-rich foods to reduce the risks of serious birth defects. in canada, mandatory fortification of selected foods with folic acid had been shown to reduce the incidence of neural tube defects by 46% compared to incidence prior to mandatory fortification. however, relying on eating a folate-rich diet alone is not recommended for preventing neural tube defects when trying to conceive because a regular diet usually does not contain enough folate to reach pregnancy requirements. all individuals who have the ability to become pregnant are advised to get 400 micrograms of folic acid daily. this daily 400 mcg dose of folic acid can be found in most multivitamins advertised as for women. higher doses can be found in pre-natal multivitamins but those doses may not be necessary for everyone. individuals who have previously given birth to a child with a neural tube defect and are trying to conceive again may benefit from a supplement containing 4.0 mg daily, following advice provided by their doctor. in canada, guidelines on folic acid intake when trying to conceive is based on a risk assessment of how likely they are to experience a neural tube defect during pregnancy. risk is divided into high, moderate, and low risk categories. high risk would include those that had a past experience with neural tube defects, either themselves or during another pregnancy. medium risk individuals are those with certain conditions that put them at higher risk for experiencing a neural tube defect. these include having a first or second degree relative or partner with a history of neural tube defects, having a gastrointestinal condition that affects normal absorption patterns, advanced kidney disease, kidney dialysis, alcohol over-use, or had another pregnancy resulting in a congenital abnormality that was folate sensitive. medium risk individuals would also include those taking medications that can interfere with folate absorption such as anticonvulsants, metformin, sulfasalazine, triamterene, and trimethoprim. low risk would include everyone else that do not fall into either medium or high risk categories. recommendations on when to start folic acid supplementation for all individuals looking to become pregnant is at least 3 months preconception. if an individual is in the high risk category, the recommended dose is 4–5 mg of folic acid daily until 12 weeks gestation and then decrease to 0.4–1 mg until 4–6 weeks postpartum or for however long breastfeeding lasts. if an individual is in the medium risk category, the recommended dose is 1 mg of folic acid daily until 12 weeks gestation and then they can either continue at 1 mg or decrease to 0.4 mg daily until 4–6 weeks postpartum or however long breastfeeding lasts. if the pregnancy is low risk to develop a neural tube defect then the recommendation for that individual is 0.4 mg daily until 4–6 weeks postpartum or however long breastfeeding lasts. all dose recommendations and risk assessment should be done with the advice of a qualified health care provider. treatment as of 2008, treatments of ntds depends on the severity of the complication. no treatment is available for anencephaly and infants usually do not survive more than a few hours. aggressive surgical management has improved survival and the functions of infants with spina bifida, meningoceles and mild myelomeningoceles. the success of surgery often depends on the amount of brain tissue involved in the encephalocele. the goal of treatment for ntds is to allow the individual to achieve the highest level of function, and independence. fetal surgery in utero before 26 weeks gestation has been performed with some hope that there is benefit to the outcome including a reduction in arnold–chiari malformation and thereby decreases the need for a ventriculoperitoneal shunt but the procedure is very high risk for both mother and baby and is considered extremely invasive with questions that the positive outcomes may be due to ascertainment bias and not true benefit. further, this surgery is not a cure for all problems associated with a neural tube defect. other areas of research include tissue engineering and stem cell therapy but this research has not been used in humans. epidemiology deaths from neural tube defects per million persons in 2012 0–0 1–1 2–3 4–6 7–10 11–15 16–20 21–28 29–69 neural tube defects resulted in 71,000 deaths globally in 2010. it is unclear how common the condition is in low income countries. prevalence rates of ntds at birth used to be a reliable measure for the actual number of children affected by the diseases. however, due to advances in technology and the ability to diagnose prenatally, the rates at birth are no longer reliable. measuring the number of cases at birth may be the most practical way, but the most accurate way would be to include stillbirths and live-births. most studies that calculate prevalence rates only include data from live births and stillborn children and normally exclude the data from abortions and miscarriages. abortions are a huge contributing factor to the prevalence rates; one study found that in 1986 only a quarter of the pregnancies with an identified ntd were aborted, but that number had already doubled by 1999. through this data, it is clear that excluding data from abortions could greatly affect the prevalence rates. this could also possibly explain why prevalence rates have appeared to drop. if abortions are not being included in the data but half of the identified cases are being aborted, the data could show that prevalence rates are dropping when they actually are not. however, it is unclear how much of an impact these could have on prevalence rates due to the fact that abortion rates and advances in technology vary greatly by country. there are many maternal factors that also play a role in prevalence rates of ntds. these factors include things like maternal age and obesity all the way to things like socioeconomic status along with many others. maternal age has not been shown to have a huge impact on prevalence rates, but when there has been a relationship identified, older mothers along with very young mothers are at an increased risk. while maternal age may not have a huge impact, mothers that have a body mass index greater than 29 double the risk of their child having an ntd. studies have also shown that mothers with three or more previous children show moderate risk for their next child having an ntd.