July 16, 2004 -- For most women, stress and anxiety come with the territory during pregnancy. Added to the stresses of daily life is a mother-to-be's fears for her unborn baby.
While a certain amount of anxiety during pregnancy may be inevitable, there is growing evidence that high levels can affect children long after birth.
A newly published study shows a strong link between maternal anxiety levels early in pregnancy and a child's susceptibility to attention deficit hyperactivity disorder (ADHD) years later. The association was stronger than that seen for any other predictor of behavioral problems during childhood, including smoking during pregnancy, low birth weight, or a mother's current stress level.
The findings support the somewhat controversial idea that exposures in the womb play a critical role in predisposing people to a host of diseases and emotional disorders later in life. Known as the "fetal programming hypothesis," the theory suggests that at certain points during pregnancy environmental exposures to the fetus in the womb significantly influence brain development, which, in turn, can impact future health.
"This is some of the strongest evidence yet to suggest that anxiety during pregnancy influences the offspring's risk for attention hyperactivity disorders," author Bea Van den Bergh, tells WebMD. "Obviously, genetic predisposition plays an important role in these disorders, but this suggests an interaction between environmental factors and genes."
Stressed Before Birth
It is well known that stress and anxiety during pregnancy can increase a woman's risk of miscarriage, preterm delivery, and giving birth to a baby that is low birth weight, but few studies in humans have examined the longer-term implications in children born to mothers stressed during pregnancy.
In this study, Van den Bergh and colleagues from Belgium's Catholic University of Leuven followed 71 mothers and their first-born children from pregnancy through early childhood. The mothers completed questionnaires designed to measure anxiety throughout their pregnancies, and the children were assessed for ADHD and other behavioral disorders between the ages of 8 and 9.
Maternal anxiety levels early in pregnancy -- during the 12th and 22nd week of pregnancy -- were strongly linked to ADHD in the children. Previous findings from the same group of mothers and children showed a link between anxiety during this developmental period and temperament during early childhood. The findings are reported in the latest issue of the journal Child Development.
Van den Bergh says pregnant women should do all they can to reduce the stresses and anxiety in their lives, especially early in their pregnancies. While the findings could produce even more anxiety among women who worry that worrying will damage their unborn babies, the researcher says she hopes it will lead to the development of better strategies for dealing with stress during pregnancy.
Obstetrician and longtime fetal development researcher Peter Nathanielsz, MD, PhD, says placing the burden of reducing stress on the mother-to-be will not work. Nathanielsz's well-publicized studies show that environmental exposures in the womb are associated with many health problems later in life including heart disease, diabetes, and obesity.
"I've been taken to task by people who say my research lays too much blame on the mom, but that is not it at all," Nathanielsz says. "The womb is the first environment we experience, and we pass more biological milestones before we are born than we will ever pass again. We can leave it to the mother to deal with stress or we can rightly recognize that this is a societal problem that has to be addressed by all of us."
Duke University obstetrics and psychiatry professor Diana Dell, MD, agrees that simply telling women to reduce the stress in their lives during pregnancy isn't enough. Dell is a spokeswoman for the American College of Obstetrics and Gynecology.
"Women are already under enormous pressure to make perfect babies, so instead of blaming moms under stress we need to figure out how to best protect moms and babies from stress and anxiety," she says.