Does Taking Vitamin D During Pregnancy Reduce the Risk of Autism?

Autism spectrum disorders (ASD) are becoming more common in children— could vitamin D deficiency during pregnancy be a culprit? 

By OBGYN Dr. Kenosha Gleaton

Vitamin D, the “sunshine vitamin,” is a fat-soluble vitamin that is found in some foods, supplements, and is produced through ultraviolet (UV) rays from the sun. Vitamin D is crucially involved in neurodevelopment, and vitamin D deficiency during pregnancy may impact a developing fetus’s brain, leading to possible adverse neuropsychological disorders like Autism Spectrum Disorder (ASD). 

Vitamin D deficiency during pregnancy and autism 

It has been reported that vitamin D deficiency during pregnancy could be a risk factor for ASD in the child. But clinical research on this topic is limited, and most of the studies are in animal models, or small human studies.

One small prospective study from Oregon Health & Science University followed pregnant mothers who already had one or more children diagnosed with autism. The mothers took 5,000 IU of vitamin D3 daily during pregnancy, and 7,000 IU daily while breastfeeding. Because the children had siblings with ASD, the expected recurrence rate was 20%. However, by the time the children in the study were over three years old, only 5% had autism. 

Should I take vitamin D supplements during pregnancy?

Pregnant individuals should get 600 IU of vitamin D daily during pregnancy, but most experts agree that supplemental vitamin D is safe in dosages up to 4,000 IU per day during pregnancy. We recommend finding a prenatal vitamin that contains vitamin D, though you can also take an additional vitamin D supplement (like our vitamin D3 gummies) in accordance with your doctor’s guidance as long as you don’t exceed the upper limit of 4,000 IU/day.

If you are vitamin D deficient, or at risk of being deficient, then you should discuss vitamin D dosing with your doctor. Vitamin D deficiency during pregnancy has been reported to be associated with pre-eclampsia, preterm birth, gestational diabetes, and more. However, in some cases, a cause effect relationship is not well-established. 

Read more about vitamin D deficiency.

Can vitamin D help a child who has already been diagnosed with ASD?

There have been numerous studies showing vitamin D levels in children with ASD are lower than average, but it is unclear if these children are born with lower vitamin D levels or develop low levels due to other factors.

Unfortunately, evidence that vitamin D supplementation improves the symptoms of ASD is lacking. One small, double-blind, randomized, placebo-controlled trial of 42 children with ASD found no meaningful difference in behavior for children taking vitamin D. However, vitamin D is relatively safe and affordable, so more research in the space is needed.  

Take-aways

• Vitamin D is crucially involved in neurodevelopment, and vitamin D deficiency during pregnancy may impact a developing fetus’s brain, leading to possible disorders like autism
• Clinical research on this topic is limited, and most of the studies are in animal models, or small human studies
• Regardless, vitamin D deficiency during pregnancy is associated with pre-eclampsia, preterm birth, gestational diabetes, and more, so it’s critical to have healthy vitamin D levels during pregnancy
• Pregnant individuals should consume 600 IU of vitamin D daily during pregnancy, but most experts agree that supplemental vitamin D is safe in dosages up to 4,000 IU per day during pregnancy

Featured Image by Scott Webb