Preventing autism perinatally - before conception
As a dietitian I was trained to individualize nutrition therapy for special need clients, whether they had an odd diagnosis or just had odd symptoms, I was trained to just go look up the whatever medical research might be available about the unusual diagnosis or symptoms. My goal while reviewing the available research was to look for any clues about what nutrients or metabolic pathways might be essential during normal function of the problem diagnosis or symptom and to see if there might be any nutrient deficiencies that could be causing the dysfunction. And then I would work with the client to figure out where their food preferences might be leaving them with unsuspected nutrient deficiencies.
Autism can be detected from umbilical cord blood so it is a condition that develops due to the perinatal or prenatal environment. Babies are not grown out of medicine. Women grow them out of food and stored nutrients. Autism is not due to a lack of anti-autism medicine. A for-profit medical industry that is determined to find a patent protected medication that will 'cure' autism is likely to waste a lot of time and money in the search for something that is impossible. It takes an incredible variety of nutrients to grow a baby over 40 weeks of gestation and ideally an additional couple of years of breastfeeding, -- not just one nutrient or a dose of some anti-autism 'cure.'
Several frequently missed genetic defects that can cause several significant nutrient deficiencies may be now overlapping in enough women who then can not detoxify the levels of formaldehyde or other toxins that are now commonly found in our food supply and in our surrounding environment. Prior to conception we need to help women identify and correct any underlying metabolic defects or chronic infections before they try to get pregnant. And men's alcohol consumption in the days prior to conception or other health factors may also be involved in the infant's risk to develop autism later in life.
An excerpt from the last very long post that has been grouped slightly differently: A summary of the factors that may interact during the prenatal and/or perinatal (three months prior to conception) time period in a way that may lead to the development of autism within the fetal brain.
Formaldehyde, a known neurotoxin, might be accumulating from several sources [3, 5], and it is difficult for humans to detoxify, and it accumulates more in the fetus and is even more difficult for the fetus to detoxify:
Aseptically packaged juices
Badly ventilated air.
Possible Folate issues. The B vitamin Folate is essential for detoxifying formaldehyde. A genetic defect can make the commonly used supplemental form, folic acid, not useful for the fetus or expectant mother who has the genetic defect (which is not commonly tested for or treated by the mainstream medical industry - nutrients are not able to be patent protected and therefore provide less of a profit). (and methylation cycle defects may also affect supplies of B12):
Simple folate/folic acid deficiency/lack of prenatal vitamin during the perinatal time period. 
Genetic defect in mother affecting the methylation cycle makes her more susceptible for folate deficiency. 
Genetic defect in the fetus affecting the methylation cycle makes it more at risk for autism. 
A methylated form of the vitamin may be more effective for reducing risk of developing autism. The natural food form, folate, is more bioactive than the supplemental form, folic acid, that is used in prenatal vitamins. 
obsessive-compulsive disorder, - can be early symptoms of a B12 deficiency. [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3271502/] Has been associated with folate deficiency, elevated homocysteine levels and impaired methylation function: [http://www.ncbi.nlm.nih.gov/pubmed/16194269]
schizophrenia, - Symptoms of schizophrenia may sometimes simply be due to an underlying deficiency of folate or B12, which could be due to an underlying genetic defect in the methylation cycle. And folate and B12 have both been found to help treat schizophrenia symptoms for some patients (or it is helping treat those patient's whose symptoms are actually due to an underlying deficiency of folate and B12 and providing the nutrients simply is helping the brain to function normally again.)
depression, - can be a symptom of folate deficiency. And the methylated form was given as a supplemental treatment, L-Methylfolate, rather than the unmethylated form, folic acid, which is the form used in prenatal vitamins. [psychologytoday.com/blog/the-integrationist/201310/depression-wont-go-away-folate-could-be-the-answer] Depressive disorders have been associated with impaired methylation: [http://www.ncbi.nlm.nih.gov/pubmed/16194269]
Possible Vitamin D Issues - it might not just be a lack of vitamin D or sunshine (essential for the mother's body to accept the foreign DNA of the new fetus rather than develop autoimmune antibodies against it - which may be able to cause brain damaging changes prenatally or later in life):
Simple vitamin D deficiency
An underlying genetic defect in the Vitamin D Binding Protein causes a tendency to become vitamin D deficient more easily than normal. [10, 11, 12] (Might a simple protein deficiency then also add a risk to a simple deficiency of all important proteins?)
allergic reaction, and - the vitamin D receptor and the Dendritic cells are what control the immune system's allergic reaction. Excerpt: "1α,25-dihydroxyvitamin D(3) (calcitriol), the biologically active form of vitamin D, is an immunomodulatory hormone, e.g. it inhibits IgE synthesis in B cells. As its clinical application is limited by hypercalcemia, synthetic vitamin D receptor (VDR) agonists that mediate immunomodulatory activities without adverse hypercalcemic effects are of great interest."- [http://www.ncbi.nlm.nih.gov/pubmed/21121929]
Getting sick during the first trimester may be creating antigens in the mom that may then affect the babies brain development, and it involves the vitamin D receptor part of the immune system. Pregnant ladies should avoid sick people and possibly avoid getting vaccinations during the first trimester - but research is still in the early phases. -- rubella, - also known as German measles, it is the R part of the MMR vaccine. It is rare in the U.S. now with less than ten cases per year but can cause defects in an expected infant if a pregnant woman gets sick with the infection prior to 20 weeks gestation. [http://www.whattoexpect.com/pregnancy/pregnancy-health/complications/rubella.aspx]
An underlying infection is present with a pathogen that is suppressing the vitamin D receptor system.
cytomegalovirus, - a viral disease that may affect vitamin D levels: "However, when outliers were removed, the association was not apparent. The effect of outliers could not be assessed when vitamin D was dichotomized because no patients with CMV antibodies had sufficient vitamin D levels after outliers were dropped." [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3134182/]
autoimmune disease, - associated with vitamin D deficiency and malfunction of the dendritic cells ability to promote self tolerance of the immune system. The dry cleaning chemical and degreaser tetrachloroethylene has been shown to cause autoimmune disease in lab animal studies on toxicity: [http://www.atsdr.cdc.gov/sites/lejeune/tce_pce.html]
hypothyroidism. - may be associated with iodine deficiency which prenatally can cause mental retardation and thyroid defects in the expected infant but it might also be caused by autoimmune disease which involves a disrupted vitamin D receptor system. Hypothyroidism in female workers has been associated with the flame retardant, polybrominated diphenyl ethers, [http://www.ncbi.nlm.nih.gov/pubmed/26606679], and the insecticide chlorpyrifos, [http://www.iss.it/binary/inte/cont/CPF_ENG.pdf], and the pesticide known as DDT dichlorodiphenyltrichloroethane also [https://preventdisease.com/news/10/022510_pesticide_exposure_underactive_thyroid.shtml], [http://www.ncbi.nlm.nih.gov/pubmed/24064777], and polychlorinated biphenyls [https://www.researchgate.net/publication/26873383_Hypothyroidism_Induced_by_Polychlorinated_Biphenyls_and_Up-Regulation_of_Transthyretin] and fluoride are also associated with risk of hypothyroidism.
schizophrenia, - vitamin D deficiency is more common in people diagnosed with schizophrenia. [http://psychcentral.com/news/2014/07/23/vitamin-d-deficiency-common-in-schizophrenia/72813.html] It can be a symptom of later stage HIV/AIDS due to increased calcium levels in the brain [Infectious Madness, book] and schizophrenia symptoms can be caused by a late stage Toxoplasma gondii infection.
Excerpt from an earlier post about intracellular pathogens that have developed ways to block or suppress the vitamin D receptor immune functions. "Other pathogens that have been shown to reduce the activity of the Vitamin D Receptor, in addition to the pathogen that causes Tuberculosis, include the mold Aspergillus, the viruses that cause Epstein-Barr chronic fatigue syndrome and HIV/AIDS, and the autoimmune diseases sarcoidosis, Crohn’s Disease, and Rheumatoid Arthritis. Elevated levels of 1, 25(OH)2D are seen with the bacterial infections: “Elevated 1,25(OH)2D appears to be evidence of a disabled immune system’s attempt to activate the VDR to combat infection.” [page 19, 1]" [https://transcendingsquare.com/2015/08/11/whether-to-be-compliant-or-to-be-healthy-seems-like-an-easy-question-to-answer/] Women with rheumatoid arthritis who get pregnant have been found to have some relief from their symptoms. Levels of the active hormone D seem to be elevated only in the areas of joint damage in RA rather than throughout the entire body. However while the woman might feel better the baby may end up being born with an intracellular bacterial pathogen - so mom might feel better for a few months but baby might suffer from juvenile RA because currently the mainstream medical industry does not recognize, test for or treat, the bacterial pathogen involved in Rheumatoid Arthritis.
Iodine deficiency and excess of fluoride, bromide or perchlorate and be a cause of hypothyroidism
hypothyroidism. - may be associated with iodine deficiency which prenatally can cause mental retardation and thyroid defects in the expected infant. Hypothyroidism in female workers has been associated with the flame retardant, polybrominated diphenyl ethers, [http://www.ncbi.nlm.nih.gov/pubmed/26606679], and the insecticide chlorpyrifos, [http://www.iss.it/binary/inte/cont/CPF_ENG.pdf], and the pesticide known as DDT dichlorodiphenyltrichloroethane also [https://preventdisease.com/news/10/022510_pesticide_exposure_underactive_thyroid.shtml], [http://www.ncbi.nlm.nih.gov/pubmed/24064777], and polychlorinated biphenyls [https://www.researchgate.net/publication/26873383_Hypothyroidism_Induced_by_Polychlorinated_Biphenyls_and_Up-Regulation_of_Transthyretin] and fluoride are also associated with risk of hypothyroidism.
depression, - can be a symptom of hypothyroidism and has been associated with vitamin D deficiency [webmd.com/depression/news/20120627/vitamin-d-deficiency-linked-to-depression]
Stress is bad for pregnant women. It uses up good nutrients and creates inflammatory chemicals.
stress, - increases cortisol and inflammatory stress chemicals, a lack of antioxidant nutrients may make it more difficult for the body to recover from the stress response. [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1876613/] And may use up stores of folate and cause elevated levels of homocysteine. [http://www.nejm.org/doi/full/10.1056/NEJMc066569] Elevated levels of cortisol during pregnancy has been shown to cause reduced growth rate in the babies in animal studies. [https://en.wikipedia.org/wiki/Cortisol]
Alcohol is bad for the fetus whether it's dad drinking in the days before conception or mom drinking prior to conception or during the pregnancy and the risks to the infant may be worse if there is also a deficiency of the mineral zinc.
alcohol, - alcohol use by the mother during pregnancy or by the father during the days prior to conception can be a cause of Fetal Alcohol Syndrome in the infant. A zinc deficiency in the pregnant woman may increase the risk of the expected infant developing FAS. [search term alcohol FAS zinc deficiency]
Zinc deficiency and B6 deficiency can be due to pyroluria, a genetic defect that can cause significant loss of zinc and B6 in the urine but it is a condition that the mainstream medical industry does not typically test for or treat. Nutrients are not able to be patent protected and therefore can not be sold for a large profit.
depression, - Depressive disorders have been associated with zinc deficiency: [https://www.psychologytoday.com/blog/evolutionary-psychiatry/201309/zinc-antidepressant]
schizophrenia, - And a zinc deficiency/copper excess is more common in schizophrenia: [http://www.academia.edu/1096257/The_Role_of_Zinc_Supplementation_in_the_Treatment_of_Schizophrenia] And a zinc deficiency prenatally may be involved in the causing schizophrenia later in life: [http://www.ncbi.nlm.nih.gov/pubmed/1491625] [http://www.bmj.com/rapid-response/2011/10/30/does-zinc-deficiency-early-foetal-life-cause-schizophrenia]
Other, other factors that may be involved in development of autism may include a variety of chemicals known to be toxic for brain development and which may be common in our modern environment. From the Abstract of a review article by Dr. Philippe Grandjean, MD and Philip J. Landrigan, MD, Neurobehavioural effects of developmental toxicity., (The Lancet Neurology, 2014): "In 2006, we did a systematic review and identified five industrial chemicals as developmental neurotoxicants: lead, methylmercury, polychlorinated biphenyls, arsenic, and toluene. Since 2006, epidemiological studies have documented six additional developmental neurotoxicants—manganese, fluoride, chlorpyrifos, dichlorodiphenyltrichloroethane, tetrachloroethylene, and the polybrominated diphenyl ethers. We postulate that even more neurotoxicants remain undiscovered. To control the pandemic of developmental neurotoxicity, we propose a global prevention strategy." 
And other factors associated with autism that were mentioned in the other hypothesis about autism and folic acid included: "valproic acid, thalidomide, alcohol, rubella, cytomegalovirus, depression, schizophrenia, obsessive-compulsive disorder, autoimmune disease, stress, allergic reaction, and hypothyroidism." - CR King 
valproic acid, - a medication commonly used to prevent seizures in epilepsy, may also be prescribed for bipolar disorder or to prevent migraine headaches. (Valporate (VPA), sodium valproate, and divalproex sodium, Depakote). It has been known to cause serious abnormalities in babies when used by pregnant women and is no longer typically prescribed to women of childbearing years. [Wikipedia]
thalidomide, - a medication that was prescribed to pregnant women for preventing nausea in the 1960s but it was discovered to cause serious birth defects. It is still used for the treatment of leprosy and still has been known to cause birth defects in the babies of women with leprosy who become pregnant. [http://toxsci.oxfordjournals.org/content/122/1/1.full]
A summary of the developmental neurotoxicants: "lead, methylmercury, polychlorinated biphenyls, arsenic, and toluene. ...manganese, fluoride, chlorpyrifos, dichlorodiphenyltrichloroethane, tetrachloroethylene, and the polybrominated diphenyl ethers."  And the other factors associated with autism that were mentioned in the other hypothesis about autism and folic acid included: "valproic acid, thalidomide, alcohol, rubella, cytomegalovirus, depression, schizophrenia, obsessive-compulsive disorder, autoimmune disease, stress, allergic reaction, and hypothyroidism." - CR King 
Autism can not be called a complete mystery anymore. When all of the known risks are combined it is clear that something is going wrong prenatally from as early as the day of conception when the sperm and egg first combine into a new baby zygote (the single cell stage of fetal development). And to be fair we have to leave God out of this -- autism is not God's will after all -lead, arsenic, manganese, fluoride and stress are products of nature but the formaldehyde producing Nutrasweet and Neotame are man made products and I don't think nature invented refined sources of methylmercury, polychlorinated biphenyls, toluene, chlorpyrifos, dichlorodiphenyltrichloroethane, tetrachloroethylene, or the polybrominated diphenyl ethers."  or valproic acid, thalidomide, or alcohol." - CR King 
/Disclosure: This information is provided for educational purposes within the guidelines of fair use. While I am a Registered Dietitian this information is not intended to provide individual health guidance. Please see a health professional for individual health care purposes./