Between 3% and 5% of American children have Attention Deficit Hyperactivity Disorder (ADHD), a condition that makes it hard for them to control their behavior and/or concentrate. Symptoms of ADHD often appear in early childhood, when a child’s hyperactivity and inattention begin to affect performance in school, social relationships with other children, and behavior at home.

Past research has indicated that ADHD—as well as most other childhood disorders—is caused by both genetic and environmental factors. Child development specialists believe that having a certain genetic makeup gives rise to the development of ADHD and being exposed to certain environmental factors can trigger or influence the severity of the disorder.

But what environmental factors increase the risk of ADHD? Some studies have suggested that using cigarettes and alcohol during pregnancy can increase the likelihood that a child develops ADHD. Other evidence indicates that exposure to lead, brain injury, and food allergy may increase a child’s chance of developing ADHD. Some researchers even speculate that a mother’s emotional state of mind during pregnancy can affect the behavior patterns of her children.

A new study in the July/August issue of Child Development found that children whose mothers experienced high levels of anxiety during early pregnancy were more likely to have ADHD and anxiety at age 8–9.

About the Study

This study included 71 mothers and their 8 and 9 year-old firstborns (38 boys and 34 girls). The women had no psychiatric disorders or history of anxiety disorders, and were largely healthy, well educated, and married.

During their pregnancies, the mothers had participated in a study that used questionnaires to assess their levels of anxiety 12–22, 23–31, and 32–40 weeks into their pregnancies, and at 1, 10, and 28 weeks after the birth of their children. The researchers also assessed the parents’ educational levels, the mother’s smoking status during pregnancy, and the birth weight of the child.

When the children were eight and nine years old, the researchers used parent, teacher, and child questionnaires, and in-person observations to discern whether the children had developed ADHD symptoms (inattention, impulsivity, disinhibition, hyperactivity), externalizing behavior (conduct disorders, aggression), internalizing behavior (anxiety, depression , withdrawal), and/or self-report anxiety (inhibition, stress in new situations). A questionnaire was also used to ascertain the mother’s anxiety at this time.

To ensure the validity of their findings, the researchers controlled for the child’s gender and birthweight, the parents’ educational level, smoking during pregnancy, and the mother’s anxiety levels after birth (measured at 1, 10, and 28 weeks, and 8–9 years after birth).

The Findings

Maternal anxiety was significantly higher 12–22 into the pregnancy than it was 32–40 weeks into the pregnancy. Mothers of boys also reported higher levels of anxiety 12–22 weeks into the pregnancy than did mothers of girls.

Maternal anxiety experienced 12–22 weeks during pregnancy was significantly associated with ADHD symptoms, externalizing behavioral problems, and self-reported anxiety in the 8 and 9 year-old children. Specifically, 22% of the cases of ADHD, 15% of the cases of externalizing behavioral problems, and 9% of the cases of self-reported anxiety could be attributed to maternal anxiety during this time of pregnancy. Anxiety at 32–40 weeks did not independently predict these problems, and there were no significant associations between maternal anxiety and internalizing problems.

This study does have certain limitations. First, the sample size was relatively small, so the results may not be applicable to the general population. In addition, using questionnaires that require subjects to gauge there own level of anxiety is highly subject and could have biased the results.

How Does This Affect You?

These findings suggest that a woman’s emotional state of mind during pregnancy may in fact have an impact on her child’s development. This study supports the “Fetal Programming Hypothesis” perspective, which asserts that being exposed to certain environmental factors during specific times prior to birth may influence some of the body’s “set points”, which can have lasting effects later in life. The researchers speculate that an increase in blood cortisol—a hormone that is produced during stress—in anxious pregnant women may impact the developing brain of their baby, predisposing them to ADHD and other behavioral problems.

Interestingly, anxiety during early pregnancy seemed to have the most profound affect on the risk of ADHD, suggesting that reducing stress and anxiety during early pregnancy may benefit the developing fetus. These results, however, do not suggest that anxiety during pregnancy is the cause of ADHD, and women who feel stressed and anxious during pregnancy should not make matters worse by assuming their child is destined to have behavioral problems. Anxiety during pregnancy is certainly only one of many factors—inside the uterus and out—that contributes to complex conditions such as ADHD.