It’s no secret: Trying to get pregnant can sometimes feel stressful, for both parents—and that’s probably normal. But new research shows that high levels of stress during pregnancy can have an impact on your child’s brain health, and it turns out, stress felt by fathers before pregnancy is also a factor.

A dad’s stress levels can change their sperm, which can affect your baby’s brain development, according to a new animal study.

Working with male mice, scientists from the University of Maryland School of Medicine found that an increase in stress hormones—known as glucocorticoids—can alter key aspects of a father’s sperm, affecting their child’s response to stress. In particular, the researchers discovered that the uptick in glucocorticoids could change the genetic material found in tiny sacs released by the duct where sperm matures. The sperm then combines with these sacs, known as vesicles, both winding up in the semen that travels the egg—and with it, changes to the genetic material.

Speaking to The Guardian, lead researcher Tracy Bale, professor of neuroscience at the University of Maryland School of Medicine, said of the findings, “What it is telling us is that there is a point in the reproductive tract of the male that responds to changes in the environment—in this case it is stress, but other groups have looked at things like dietary challenge. These effects … seem to be lasting in the father.”

The yet-to-be-published research was presented at the 2018 American Association for the Advancement of Science annual meeting in Austin, Texas.

Bale’s latest research builds on a previous mice study that showed stress could change microRNA production in sperm. In 2015, Bale, then working at the University of Pennsylvania, discovered that male mice exposed to a mildly stressful event, such as being briefly restrained, created sperm with higher levels of microRNA, which seemed to reduce their offspring’s response to stress. MicroRNA, contained in the vesicles, play a vital part in which genes become functional proteins.

But how, exactly, does the increase in microRNA affect a baby’s brain development? “The hypothalamus, the part of the brain that determines your stress response, has been wired differently,” Bale told The Guardian.

Bale and her team of researchers have noted that a dampened stress response can affect a child’s overall mental health. That’s because studies have linked an inability to handle stress well with an increased risk of certain neurodevelopmental disorders such as depression or post-traumatic stress disorder.

A greater understanding of how a father’s stress levels can affect a child’s brain development can give doctors a better understanding of these disorders, and how to detect and prevent them, according to the scientists.

For dads-to-be, it’s important to recognize that trying to conceive can be stressful. Taking time to de-stress now is a good idea for dad and his future baby.