Human Development

Tracking Stress and Depression Back to the Womb (12/04)

By listening intently to movements and heartbeats, researchers are finding that the fetuses of mothers who are stressed or depressed respond differently from those of emotionally healthy women.

After birth, studies indicate, these infants have a significantly increased risk of developing learning and behavioral problems, and may themselves be more vulnerable to depression or anxiety as they age.

The studies, researchers caution, are preliminary. Stress or depression during a mother’s pregnancy is only one among many influences that affect an infant’s development.

Even among mothers who are depressed or highly stressed, the rate of emotional and behavioral problems in children is still very low.

“The last thing pregnant women need is to have something else to worry about,” said Dr. Janet DiPietro, a developmental psychologist at the Johns Hopkins University Bloomberg School of Public Health.

The studies reflect growing evidence that stress and depression can have early and lasting effects on a child’s life.

If the findings hold up, experts say, they could eventually lead obstetricians, midwives and other health professionals who care for pregnant women to include mental health screening as a routine part of prenatal examinations. Such screening could allow doctors to recommend therapy or treatment for pregnant women who suffer from depression or other disorders.

“We could be intervening earlier,” said Dr. Catherine Monk, an assistant professor in the psychiatry department at the College of Physicians and Surgeons at Columbia. “Prenatal care is an optimal time to do mental health screening, but we don’t.”

The effects of stress on a fetus have been well documented in animal studies. In rats, researchers have found, babies born to stressed mothers show permanent changes in brain chemistry and behavior. For example, rat pups exposed prenatally to elevated levels of the stress hormone corticosterone were born with reduced numbers of corticosterone receptors in the brain, and the animals showed exaggerated responses to stress.

In humans, there is convincing evidence that mothers who are stressed in pregnancy are more likely to give birth to preterm or infants with low birth weights.

In recent years, scientists have begun to home in on more subtle effects, studying how unborn fetuses respond to their mothers’ anxiety or depression, the emotional health of the infants after birth and how they fare later in childhood. Some studies have offered unusual glimpses into the symbiotic relationship between a mother and a developing child.

Dr. Monk has looked at the increase and decrease in a fetus’s heart rate when its mother is under stress.

In one study, women who were in the third trimester of pregnancy went through psychological screening for depression and anxiety. They were then asked to perform a series of stress-inducing computer tasks. As expected, all the women showed increases in heart rate, respiration and blood pressure. The responses of the fetuses were more varied. The fetuses of mothers who were depressed or had anxious personality styles showed increases in heart rates. In contrast, the heart rates of fetuses whose mothers were emotionally healthy showed no fluctuations.

Dr. Monk said the fetuses were not simply mimicking their mothers’ responses.

“What this leaves us with is another interpretation,” she said. “The fetuses of depressed or high anxious women are more reactive to stimuli than other fetuses.”

She compared the fetuses’ responses to the way people in a waiting room might react differently to a door being slammed. In this case, a fetus might be reacting to the mother’s increased heartbeat or breathing, or to a jolt of stress hormones.

Dr. Monk said depressed women tended to have more difficulty handling stress, which leads to higher levels of stress hormones like cortisol. She speculated that those higher levels, in turn, might make the fetus more jumpy.

“My hypothesis is that over the course of gestation, they have been exposed to an altered in utero environment, which includes increased levels of stress hormones,” Dr. Monk said. “This may make fetuses more susceptible to stressors in the future, and by extension, because stress plays a role in the development of depression, may make them more vulnerable to depression in the future.”

Though stress and depression are closely intertwined, researchers believe that stress is the more potent player in affecting prenatal development. In a study by Dr. DiPietro, pregnant women who perceived their lives, and in particular their pregnancies, as stressful, had fetuses who were more active in an ultrasound test.

Other studies have linked higher levels of stress hormones in the mother with a more active fetus.

Dr. DiPietro has found that more active fetuses tend to become more active 1-year-olds, providing some evidence that the effects are not transient.

In newborns, researchers have also found that the effects of a mother’s depression lingered.

A study published this year in Infant Behavior & Development compared 70 depressed pregnant women with 70 women who were not depressed. The study found that compared with the infants of the healthy mothers, the newborns of mothers with depression symptoms had higher cortisol levels and lower levels of dopamine and serotonin, two neurotransmitters that have been tied to depression.

The newborns also had less developed learning skills, they were less responsive to social stimulation, and they were less able to calm themselves when agitated, said Dr. Tiffany Field, the author of the study and director of the Touch Research Institutes at the University of Miami School of Medicine.

In another study, Dr. Monk put newborn babies in specially designed bassinets that were tilted 30 degrees up or down, a standard method of testing a newborn’s responsiveness. When a baby’s head is down, the heart rate normally decreases in response to the stress. But newborns with depressed mothers showed a smaller decrease in heart rate, suggesting that they were less able to adapt to stress.

What begins in the womb persists into childhood, researchers find. In a study published in 2002 in The British Journal of Psychiatry, researchers asked 7,448 women in England to assess their level of stress while they were pregnant and answer questionnaires about their children’s behavior at age 4. The study found that children whose mothers reported high levels of anxiety in late pregnancy were more likely to have behavior problems – most notably attention difficulties – as 4-year-olds.

“Women who scored in the top 15 percent of anxiety had double the risk of having a child with severe behavioral problems,” said Dr. Thomas O’Connor, a professor of psychiatry at the University of Rochester, who is an author of the study.

The children in the study had a 10 percent chance of having such problems, Dr. O’Connor said, compared with a 5 percent risk among children in the general population.

Dr. Vivette Glover, a perinatal psychobiologist at Imperial College London and another author of the study, noted that even though the children of stressed mothers were at increased risk, the rate of behavior problems remained very low.

“Even with this anxious group of women, 90 percent of children don’t have these behavioral problems,” Dr. Glover said. “So even if a woman is pretty anxious, her children are probably going to be fine.”

Screening pregnant women for mental health problems is quite likely to be controversial.

“In terms of public health, it’s very important if we could reduce the incidence of behavioral problems by treating women during pregnancy,” Dr. Glover said.

She noted that cognitive behavioral therapy had proven highly successful in treating adults who suffer severe anxiety.

Some researchers say that any recommendation for screening and treatment during pregnancy is premature because the research is still prel

iminary. They point to studies suggesting that a mother’s stress may in some cases be beneficial to her fetus.

In one study, 2-year-olds whose mothers reported high levels of anxiety in pregnancy had better motor and cognitive skills than children whose mothers did not report being highly anxious.

Some experts say a fetus’s awareness that its mother is stressed may serve an evolutionary purpose, preparing it for entry into a difficult world.

“If a fetus is constantly going to be threatened after he is born, and there’s danger to its well-being, it may make sense for it to develop a system that produces big responses to stress,” said Dr. Pathik D. Wadhwa, director of the Behavioral Perinatology Research Program at the University of California, Irvine.
[NYT, http://www.nytimes.com/2004/12/07/health/psychology/07depr.html?pagewanted=all, L. Tarkan, 7Dec04]
Comment: Articles like these are a real problem for the pro-abortion groups. How can a “clump of cells” or “potential life” react to the mother’s stress in the womb? N. V., R.N.