I think this topic is too important for it to go discussed meagerly or without a consensus opinion - however loose - based on an array of the most current exhaustive studies on the condition. Too often these findings pop up in popular media without any backdrop or without the larger context of other studies, whether with similar or dissimilar findings.

Here is a study that links autism to low iron intake among pregnant women:

  Iron deficiency affects 40%–50% of pregnancies. Iron is critical for early 
  neurodevelopmental processes that are dysregulated in autism spectrum 
  disorder (ASD). We examined maternal iron intake in relation to ASD risk in 
  California-born children enrolled in a population-based case-control study 
  (the Childhood Autism Risks from Genetics and the Environment (CHARGE) Study)
  from 2003 to 2009 with a diagnosis of ASD (n = 520) or typical development 
  (n = 346) that was clinically confirmed using standardized assessments.
  .
  .
  The highest quintile of iron intake during the index period was associated 
  with reduced ASD risk compared with the lowest (adjusted odds ratio = 0.49, 
  95% confidence interval: 0.29, 0.82), especially during breastfeeding. 
  Low iron intake significantly interacted with advanced maternal age and 
  metabolic conditions; combined exposures were associated with a 5-fold 
  increased ASD risk. Further studies of this link between maternal supplemental 
  iron and ASD are needed to inform ASD prevention strategies.[1]

[1] Maternal Intake of Supplemental Iron and Risk of Autism Spectrum Disorder

http://aje.oxfordjournals.org/content/early/2014/09/22/aje.k...