How concerned should you be? Here's everything you need to know.

By Sarah Bradley
March 08, 2019
Pregnant Woman with Doctor
Credit: Image Point Fr/Shutterstock

March 8, 2019

Mothers exposed to severe infections during pregnancy have an increased risk of delivering a baby who develops autism or depression later in life, says a new study published in JAMA Psychiatry, a journal of the American Medical Association.

Study authors searched the national health registry of Sweden using hospital diagnosis codes for infection to identify all the pregnant women hospitalized between 1973 and 2014. After analyzing the data for more than one and a half million children born during that time frame, they found that infections during pregnancy increased the risk for autism and depression in childhood and adulthood. Exposure to infection increased autism rates by 79 percent and depression rates by 24 percent.

The authors also looked for connections between maternal infection and bipolar disorder and psychosis, but did not find a significant increase in risk; this was largely due to the conservative measures of the study, says co-author Kristina M. Adams Waldorf, M.D., professor of obstetrics and gynecology at the University of Washington.

"It doesn't mean there's no relationship [between other psychiatric illnesses and infection], it was just the way we constructed our analysis of the data," she explains. "We also didn't look at things like ADHD or study the difference between boys and girls, but we can do that in the future."

Scientists and researchers know that genetics are partially to blame for autism spectrum disorders, but this new study shines a light on another potentially important factor as well: inflammation. According to Dr. Adams Waldorf, other studies have found that inflammation caused by infection during pregnancy can have effects on the fetal brain, whether the infection happened to the mom or the baby. Because of this connection, inflammation may be the key to understanding why infection exposure raises the risk of psychiatric disorders.

Unfortunately, inflammation is too vague of a metric to be studied through reviews of health registry data–but infection isn't, which is why Dr. Adams Waldorf and her colleagues chose to focus on it. The team looked at hospital diagnostic codes for both bacterial and viral infections, such as sepsis, influenza, pneumonia, meningitis, and urinary tract infections, among others.

If you're wondering why UTIs are included on this list of otherwise severe infections, there's a good reason: Dr. Adams Waldorf says that given the scope of the study, it wasn't possible to parse out individual infection codes to see if patients had coexisting conditions or illnesses. In other words, it's reasonable to assume that some of those patients had actually been hospitalized for pre-eclampsia or other more serious issues or injuries (while also having UTIs).

"This is not a story about [pregnant women who had] the common cold or strep throat," says Dr. Adams Waldorf.

Basically, you don't need to stress about every sniffle, cough, or low-grade fever that strikes while you're pregnant. But severe infections requiring hospitalization are possible during how worried should you be about the link between infection and inflammation? Well, the uncomfortable reality is that you'll be exposed to bacterial and viral infections while you're pregnant (because as much as you may want to, you can't exactly spend nine months walking around in a sterilized bubble).

Thankfully, though, you don't have to panic: Dr. Adams Waldorf says that while the study results are significant on a population level, for the average individual contracting an infection during pregnancy does not guarantee that your baby will have a psychiatric disorder.

"Normally the autism risk is 1 in 59, and when you apply our findings it becomes 1 in 33," says Dr. Adams Waldorf. "So it becomes more likely, but not 100 percent." In the context of the study findings, the depression risk increases from 1 in 15 to 1 in 12.

The other piece of good news? There are some easy steps you can take to at least minimize–if not totally prevent–your chances of contracting a severe infection. Dr. Adams Waldorf recommends getting in touch with your doctor right away if you suspect illness because rapid and early treatment of infections (in line with what's considered safe for the baby) is ideal. She also suggests talking to your doctor about any travel you may be planning in an effort to avoid regions involved in outbreaks of dangerous illnesses. Both the measles and Zika viruses can cause particularly severe complications during pregnancy.

Lastly? Stay up-to-date with all recommended vaccines during pregnancy, including the influenza vaccine. Dr. Adams Waldorf notes that only two-thirds of pregnant women typically receive the flu shot, with the other one-third turning it down partly out of fear that it will harm their baby.

"Ironically," she says, "if you don't get the vaccine and then you get the flu, that's when you're more likely to harm your baby."

According to the Centers for Disease Control and Prevention, pregnant women who don't receive the flu shot are more likely to suffer severe symptoms if they contract the flu and are more likely to be hospitalized; since numerous CDC studies have proven the vaccine to be safe during pregnancy, getting a flu shot is a simple and easy preventative measure to take.