Although there is no confirmed cause of autism, various studies, including a new one done by the Centers for Disease Control and Prevention suggests that overly long or short birth spacing might be linked to autism. The study, published in Autism Research, is based on data from over 350 kids with autism spectrum disorder, 600 with developmental disorders, and 524 without any disorders at all. Researchers found, according to the Daily Mail, that both "too long" or "too short" birth spacing was "uniquely" related to autism, but not any other disorders.
There have been six other studies looking to this correlation, according to the Daily Mail, but the evidence hasn't been conclusive yet that birth spacing is a cause of autism. But it has affirmed the CDC's recommendation that women don't wait more than four years between births to possibly lower the chances of developmental disorders.
Likewise, the study authors warn that women need at least 18 months to get back all the nutrients they need to have a healthy pregnancy. They also recommend waiting more than 18 months to avoid premature birth, low birth weight, or placenta abruption. However, in 2014, for example, about 29 percent of mothers had a birth spacing of less than 18 months, according to the CDC.
The study authors suggest that some of the short spacing trends, which are on the rise, according to the most recent CDC data, are due to women waiting longer to have children and then having others in quick succession. Or not getting an assessment from their doctor if the second pregnancy is taking longer than expected, which could also help them with birth spacing planning.
Dr. Laura Schieve, the lead author of the CDC study, said in a statement:
These findings support existing guidelines on pregnancy spacing and further highlight the association between autism and pregnancy health. Couples thinking about getting pregnant should discuss pregnancy planning with a trusted doctor or healthcare provider.
To confirm their findings, the researchers also examined data from the Study to Explore Early Development, or SEED, which is a multi-year, multi-location study of children with autism spectrum disorder. The data showed that children who are conceived within 18 months after their sibling were twice as likely to be severely autistic than those born within the 18-month to a five-year time frame. Kids who were conceived after that period were 1.8 times more likely to be severely autistic.
Children conceived "too soon" or "too late" and had ASD were also more likely to be delivered prematurely and are male. A 2016 study by the World Health Organization appeared to find the same correlation between autism and birth spacing.
Dr. Agustin Conde-Agudelo, a research at the WHO, told CBS News at the time that although they noted the correlation, they weren't sure exactly why it occurred, but it likely has something to do with the health of the mother and the quality of her pre-natal care. A 2014 study done at the University of California found a correlation between iron deficiencies — which affects 40 to 50 percent of pregnancies — and autism, as well.
Dr. Paul Wang, the head of medical research for Autism Speaks told CBS News that he wasn't surprised by those findings, but felt that the 2016 WHO study was a clear sign that more research needed to be done into how nutrition affects autism diagnoses.
Again, it's important for parents everywhere to know that there is no confirmed cause of autism and that it's very likely autism is brought on by a number of factors. Until more research is done, the most anyone can do is consult with their doctor and ensure that women get consistent, quality pre-natal care as they plan for their families.
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