Prenatal Inflammation Increases Autism Risk in Children
Autism is a complex syndrome with a largely unknown cause. Studies have looked at the prenatal environment to help identify factors that may be preventable. Inflammation during pregnancy may be one common pathway that increases the risk for autism spectrum disorders.
C-reactive protein is produced by the liver and increases when there is inflammation throughout the body. Researchers analyzed blood samples collected from pregnant women in Finland as part of the Finnish Maternity Cohort. The FMC consists of 1.6 million specimens from about 810,000 women.
Finland is also one country that maintains a national registry of childhood autism cases collected from hospital admissions and outpatient treatment records.
From these sources, researchers analyzed the CRP levels in archived maternal serum corresponding to 677 childhood autism cases and an equal number of matched controls. For those in the highest quintile, there was a significant 43% elevated risk not explained by maternal age, paternal age, gender, previous births, socioeconomic status, preterm birth or birth weight.
"Elevated CRP is a signal that the body is undergoing a response to inflammation from, for example, a viral or bacterial infection," said lead scientist on the study, Alan Brown, M.D., professor of clinical psychiatry and epidemiology at Columbia University College of Physicians and Surgeons, New York State Psychiatric Institute, and Mailman School of Public Health. "The higher the level of CRP in the mother, the greater the risk of autism in the child."
Brown cautioned that the results should be viewed in perspective since the prevalence of inflammation during pregnancy is substantially higher than the prevalence of autism.
"The vast majority of mothers with increased CRP levels will not give birth to children with autism," Brown said. "We don't know enough yet to suggest routine testing of pregnant mothers for CRP for this reason alone; however, exercising precautionary measures to prevent infections during pregnancy may be of considerable value."
The CDC offers ten tips to help pregnant women avoid infections:
1. Wash your hands often with soap and water, especially when…
• Using the bathroom
• Touching raw meat, raw eggs, or unwashed vegetables
• Preparing food and eating
• Gardening or touching dirt or soil
• Handling pets
• Being around people who are sick
• Getting saliva (spit) on your hands
• Caring for and playing with children
• Changing diapers
If soap and running water are not available, you can use alcohol-based hand gel
2. Try not to share forks, cups, and food with young children.
Wash your hands often when around children. Their saliva and urine might contain a virus. It is likely harmless to them, but it can be dangerous for you and your unborn baby.
3. Cook your meat until it’s well done.
The juices should run clear and there should be no pink inside. Do not eat hot dogs, luncheon meats, or deli meats, unless they are reheated until steaming hot. These undercooked meats and processed meats might contain harmful bacteria.
4. Avoid unpasteurized (raw) milk and foods made from it.
Do not eat soft cheeses such as feta, brie, and queso fresco unless they have labels that say they are pasteurized. Unpasteurized products can contain harmful bacteria.
5. Do not touch or change dirty cat litter.
Have someone else do it. If you must change the litter yourself, be sure to wear gloves and wash your hands afterwards. Dirty cat litter might contain a harmful parasite.
6. Stay away from wild or pet rodents and their droppings.
Have a pest control professional get rid of pests in or around your home. If you have a pet rodent, like a hamster or guinea pig, have someone else care for it until after your baby arrives. Some rodents might carry a harmful virus.
7. Get tested for sexually transmitted diseases (STDs), such as HIV and hepatitis B, and protect yourself from them.
Some people that have HIV, hepatitis B, or an STD do not feel sick. Knowing if you have one of these diseases is important. If you do, talk to your doctor about how you can reduce the chance that your baby will become sick.
8. Talk to your doctor about vaccinations (shots).
Some are recommended before you become pregnant, during pregnancy, or right after delivery. Having the right vaccinations at the right time can help keep you healthy and help keep your baby from getting very sick or having life-long health problems.
9. Avoid people who have an infection.
Stay away from people who you know have infections, such as chickenpox or rubella, if you have not yet had it yourself or did not have the vaccine before pregnancy.
10. Ask your doctor about group B strep.
About 1 in 4 women carry this type of bacteria, but do not feel sick. An easy swab test near the end of pregnancy will show if you have this type of bacteria. If you do have group B strep, talk to your doctor about how to protect your baby during labor.
A S Brown, A Sourander, S Hinkka-Yli-Salomäki, I W McKeague, J Sundvall, H-M Surcel. Elevated maternal C-reactive protein and autism in a national birth cohort.Molecular Psychiatry, 2013; DOI: 10.1038/mp.2012.197
Centers for Disease Control and Prevention: Prevent Infections in Pregnancy