Fetus to Mom: You're Stressing Me Out! (cont.)
"Who you are and what you're like when you're pregnant will affect who that baby is," says Janet DiPietro, a developmental psychologist at Johns Hopkins University. "Women's psychological functioning during pregnancy -- their anxiety level, stress, personality -- ultimately affects the temperament of their babies. It has to ... the baby is awash in all the chemicals produced by the mom."
The Womb Is a Busy Place
So, how does a mom's stress get passed onto her fetus? Researchers aren't exactly sure which stress responses play the largest role, but it's clear that when a pregnant woman experiences anxiety, her body produces chemicals that affect the baby, too. Her nervous system, for instance, stimulates the release of epinephrine and norepinephrine, stress hormones that constrict blood vessels and reduce oxygen to the uterus.
Since a very significant decrease in blood flow is probably necessary to compromise development of the fetus, Dr. Wadhwa says that another stress response is more likely to affect fetal growth and pre-term labor. That is, when pregnant women experience stress, particularly in the first trimester, the placenta increases production of corticotropin-releasing hormone (CRH), which regulates the duration of pregnancy and fetal maturation.
CRH is one of the most exciting recent scientific discoveries that could explain why women go into labor when they do. Called the "placental clock," CRH levels measured in the mother's blood early in pregnancy -- between 16 and 20 weeks -- can predict the onset of labor months later. Those with the highest levels will likely deliver prematurely, and those with lowest levels are apt to deliver past their due dates.
And it appears that stressful events occurring during the first trimester are most critical in signaling early labor. "That's very important because it used to be thought exactly the opposite -- that women become fragile as term approaches. Indeed, our data suggests that women become psychologically stronger," says Dr. Curt Sandman, professor and vice chairman of the department of psychiatry at University of California, Irvine.
Monitoring CRH levels and managing stress that early in pregnancy may have important implications in reducing pre-term delivery, says Dr. Christine Dunkel-Schetter, a professor of psychology at UCLA. Dr. Dunkel-Schetter is working on two studies (one with Drs. Wadhwa, Hobel and Sandman) to determine who is at highest risk for pre-term birth and what types of stresses are the biggest contributors.
"It appears we will be able to show that stress in pregnant women early in pregnancy leads to an early rise in CRH, which then leads to an early delivery," she says. "What we can't do yet is diagnose which women are most at risk. But we're close, and very soon it will be appropriate for women to be asking their doctors if their level of stress should be assessed systematically."
What's Too Much ... and for Whom?
Tiffanie Pomerance of Los Angeles remembers when she was admitted to the hospital during her first pregnancy after a sonogram found that her cervix had started to dilate at 19 weeks. Doctors stitched her up but she started having severe contractions and was hospitalized. Everyone, including her husband and family, was worried.
"We just sat in the hospital room staring at the fetal monitor, looking at how many contractions I was having. We all thought I was going to lose the pregnancy," says Pomerance, 32. Her mother finally covered the monitor with a towel when Dr. Hobel explained that worries would exacerbate her condition. Sure enough, she started to notice that contractions got worse when she was more anxious.
In hindsight, Pomerance says her hectic lifestyle as a speech therapist -- working 12-hour days, dividing her time between three nursing homes and grabbing lunch while standing -- probably contributed to her problem in the first place. She slowed down considerably with her second pregnancy. Fortunately, she carried both babies to 35 weeks.
Like most women, Pomerance had no idea how much stress could put her over the edge. "I was under your everyday type of stress. I thought that I would do it all, plus work out every day at the gym. Now I tell anyone who's pregnant to slow down a bit."
That's what makes health providers so reluctant to emphasize the connection between stress and pregnancy problems. They say a lot of the differences come down to women's personalities and how they cope with stress. Besides, who wants to lay even more guilt and anxiety on a woman who is already stressed?
Dr. Dunkel-Schetter says she's hoping to nail down the biggest predictors of stress and devise a questionnaire that women could take, along with the blood test to measure CRH levels, to determine who's at highest risk. She says it appears that women who are constantly anxious or fearful may be most susceptible to problems during pregnancy.
"Stress can be lots of things," she says. "What you'll see in the literature (are) these lists of life events -- 'Did somebody die? Did you lose your job?' But those events are not what's leading to early delivery. What I see in our work that's leading to early delivery is being a generally anxious person ... for instance, a lot of fear about the pregnancy and delivery."
But she says it's a continuum. "Low levels of anxiety we all know and feel -- sometimes more, sometimes less," says Dr. Dunkel-Schetter. "The highest level is somebody who has panic attacks or is extremely fearful of many things, and it's probably the case that the higher you are on this continuum, the more risk to your physiology in pregnancy."
Personality traits that might account for some women being better able to handle stress include optimism, self-esteem, a feeling of control over one's life, emotional suppression or expression, and hostility, says Dr. Wadhwa.
So, What's a Mother To Do?
Dr. Hobel worked in France with one of the first obstetricians to successfully reduce pre-term births. The program he devised included work leaves as early as 24 weeks into the pregnancy and nurse-midwife home visits to help women handle psychosocial stress. He started a similar program for 12,000 women in Los Angeles in the 1980s; pre-term births dropped 21% at a time when pre-term birth rates were increasing in the city and nationally.