An interesting study released in April 2012 by the UC Davis MIND Institute discovered a startling link between the state of the mother's health while pregnant and the chances of her unborn child developing autism. If the mother was obese - having a body mass index (BMI) of 30 or larger - this affected her child's chances of developing autism. The risk factor went up by a full 67%.
Autism was not the only medical issue that this study looked at. When looking at all ranges of developmental disorders, the study found that the obese women had twice the rate of issues in their children, compared with healthy weight mothers.
Diabetes made the situation even worse. Women with diabetes more than doubled the risk factor for their unborn children.
As of 2012, a full third of all women of childbearing age are obese. This percentage is far larger than in past decades. Researchers wonder if it is this increase in the number of obese women which has contributed to the rising rates of autism. That is, back in the 1950s relatively few women were obese. Autism rates at the time were relatively low. As we headed into the 1990s and 2000s, the obesity rates in the US skyrocketed. Autism rates also skyrocketed. It would seem, based on this research, that the two are at least in some small part related.
Researchers still lack many answers in the autism puzzle. There are many different components of autism. There appears to be a complex web of interconnected issues which cause a child to be susceptible or non-susceptible to autism. That being said, this study seems to find that - at least for a portion of children - the trigger was the obese state of the mother.
In a way, this study seems similar to the initial studies that found smoking impacted pregnancy. At the time, many scoffed at the idea that what a mother did to herself affected her child. The assumption was that the fetus was safe within its womb and the mother could do whatever she wished to her own body. However, study after study demonstrated that the mother's smoking caused complications for the fetus' healthy growth.
Similarly, mothers used to routinely drink alcohol during pregnancy - many times in large amounts! In modern times we realize that drinking alcohol in more than small amounts can cause a wide variety of birth defects. What goes on in the mother's system does affect the fetus.
So it makes sense here that the mother's state of obesity - with the myriad of health issues that can go along with that - could affect the fetus and its development. Perhaps it is the blood sugar swings. Perhaps it is hormonal issues. Hopefully with this starting point more research can be done to narrow down exactly what it is in the obese woman's system which is causing the harm.
Until then, it's important for women to talk with their doctors about their weight if they are trying to get pregnant, and to do their best to create a healthy lifestyle that allows them to be as fit and healthy as possible. It is best for the mother, and best for the baby as well.
Note: I have several family members who are on the autism spectrum.