The idea that a woman's emotional state during pregnancy affects her unborn child has persisted for centuries and has, in recent years, been supported by science.
Called the "fetal programming hypothesis," it theorizes that certain disturbing factors occurring during certain sensitive periods of development in utero can "program" set points in a variety of biological systems in the unborn child. This, then, affects the ability of those biological systems to change later in life, resulting in difficulties adapting physiologically and ultimately predisposing a child to disease and disorder.
We decided to investigate the affect of high levels of anxiety during a woman's pregnancy on her child's susceptibility for attention deficits, hyperactivity, acting out and anxiety disorders in childhood. We also wanted to learn whether there are specific vulnerable periods during the pregnancy in which this anxiety "programs" the child's biological system, thus increasing the fetus' susceptibility for such disorders.
We evaluated data collected on 71 normal mothers and their 72 first-born children during pregnancy and when their children were 8 or 9. The mothers completed questionnaires to measure their anxiety levels throughout their pregnancy. When the children were 8 or 9, the mothers, a teacher, and an impartial observer completed questionnaires to measure the child's attention and hyperactivity, acting-out behavior and anxiety level.
Our results suggest that the period between 12 and 22 weeks of the pregnancy is a particularly vulnerable period; only maternal anxiety during this period predicted childhood disorders at age 8 and 9. Importantly, the effect of anxiety affected the fetus more than any other factor, including smoking during pregnancy, low birthweight, or anxiety of the mother when the child is 8 or 9.
The results provide some of the strongest indirect evidence available today that a woman's anxiety during pregnancy may program some set point in the early developing brain of the fetus, thus enhancing the child's susceptibility for childhood disorders such as attention deficit, hyperactivity, acting-out and anxiety problems. Clearly, many questions on exactly how fetal programming works in humans, and how the timing, kind and duration of environmental disturbances are related to altered neurobehavioral development, are still unresolved.
Evidence from this and other studies, however, provide an impetus for developing prevention, intervention and support programs for highly anxious pregnant women. These programs could include stress reduction instructions as well as treatments to reduce anxiety and neuroendocrine reactions to stress throughout the pregnancy, or even before conception. They may benefit not only the mother but also the developing child.