by Patricia Hughes

Various studies conducted over the past two decades have demonstrated the ability of the fetus to hear sound. The inner ear is fully developed in last trimester of pregnancy. By 26 weeks, most respond with an increase in heart rate to sound stimulation. Many studies have pointed to the change in heart rate as a positive sign that the baby is stimulated by the music.

One study published in the Music Educators Journal looked at the effect of exposure to music in the prenatal period. Some participants were given music in the womb, either sedating or stimulating musical selections. After the birth of the baby, the parents and infants visited the researcher, and a range of activities and responses were observed by researchers. The study found that exposure to music in the prenatal period seemed to be linked to increased attention, more sound imitation and earlier vocalization in the baby.

Most of what the fetus hears is the mother’s voice and internal sounds of the mother’s body, such as breathing, movements and other sounds. There have been many studies that suggest the mother’s voice is the preferred sound of newborns, who appear to recognize their mother’s voice at birth. Singing along with music makes sense because it gives baby the opportunity to hear your voice and music.

It makes sense that stimulation of the brain with music would have a positive effect. It is when the baby is growing in the mother’s body that the majority of brain development occurs. The idea behind research into music exposure during the pregnancy is designed to enhance the development of the brain with appropriate stimuli. Research continues into this subject and determining which music has the most positive effect.

Not all scientists agree that music has positive effects on the fetus. Some reject the theory that an increase in heart rate signals a positive response in the fetus. One such researcher is University of California neuroscientist Gordon Shaw. Shaw suggests the change could be a signal the baby is not comfortable with the sound.

There is some evidence to suggest the type of music may influence the baby’s response. Soothing, classical music and nature sounds are believed to be soothing, while louder types of music may startle the baby.

Another factor is the volume of the music, which could be played too loudly. Some people believe the sounds are muffled and increase the volume or put speakers or headphones on the abdomen directly playing into the baby’s head. Sound is conducted by the amniotic fluid and it is easy for this method to produce music that is too loud for the baby.

It’s important to note that there are no long term studies that demonstrate listening to music in the womb will influence the baby’s intelligence or translate into success in learning later. However, this idea is based on anecdotal evidence that classical music stimulates different areas of the brain, which is thought to stimulate better connections in the brain. The hypothesis is that the increase in connectors will result in enhanced memory and information processing functions of the brain later. This theory has yet to be proven with research, and may or may not turn out to be the case.

Whether or not exposure to music will make baby smarter, there is some evidence to suggest soft music, such as quiet classical music and nature sounds have a calming effect on the baby. This often continues after birth. Many babies are soothed by the same soft music they heard during the pregnancy and recognize the rhythm. Several studies have demonstrated the newborn’s ability to recognize certain music selections that were played during pregnancy.

Music benefits mom by helping to her to relax or lifting a low mood. That is good for the baby because research has demonstrated that baby is affected by mom’s emotions. So, choose music that you find relaxing and not too loud. Loud music is not good, as it can startle the baby. A general rule of thumb is to keep the music to the level that is played in stores.

Products are sold to parents as essential tools for playing music for the baby and reaping any benefit that may result from music exposure. A typical style is a belt that is worn around the belly to project the music to the baby. Check the decibel level to make sure the music is at a comfortable level for baby. These products are nice, but not necessary. Because the amniotic fluid conducts sound well, playing music in the background as you go about your day works too.

Fetus to Mom: You’re Stressing Me Out!

Dr. Calvin Hobel, a perinatologist in Los Angeles, has spent much of his career trying to document the effects of stress on pregnancy and to figure out how best to get pregnant women to relax. Not only does he see the importance clinically, but he’s reminded of it daily.

Beginning with his 45-minute commute to Cedars Sinai Medical Center, Dr. Hobel watches women putting on makeup in their cars, wolfing down bites of breakfast … and the clincher? Pregnant women who come to yoga classes to learn how to relax have to take a breather — to answer cell phones they just couldn’t leave behind.

Stress is such a familiar part of women’s lives that many just squeeze a pregnancy right into all the hubbub. Even if women wonder whether it’s bad for their developing fetuses, it’s often hard to get a straight answer, mainly because most doctors don’t know how much stress is too much — or for whom.

But researchers, including Hobel, are getting closer to unlocking the mystery.

For one thing, a growing number of studies are confirming what used to be considered just an old wives’ tale — that stress really isn’t good for pregnant women. It not only increases the risk of pre-term labor, but possibly a host of other problems for babies after birth.

Even more important — and clearly more difficult to discern — researchers are close to being able to predict who’s most susceptible to stress and at highest risk for complications, such as pre-term birth. In fact, some say it won’t be long before health-care providers have the tools to head off these problems before it’s too late.

“Stress is a silent disease,” says Dr. Hobel, director of maternal-fetal medicine at Cedars Sinai and a professor of obstetrics/gynecology and pediatrics at University of California, Los Angeles (UCLA). “Pregnant women need to be educated in recognizing when they have stress, the consequences and some of the simple things they can do to make a difference.”

Throw Out the ‘Blueprint’

Developmental biologists once thought fetuses were conceived with a “blueprint” from their parents’ genes. As long as you gave the growing fetus the right nutrients and avoided harmful substances, this blueprint would develop into a healthy baby. That’s not what experts believe anymore, says Dr. Pathik Wadhwa, assistant professor of behavioral science, obstetrics and gynecology at University of Kentucky College of Medicine.

“This view has more or less been completely turned upside down,” says Dr. Wadhwa, who is co-editing a special issue of scientific papers on pregnancy and stress to be published in Health Psychology next year. “At each stage of development, the organism uses cues from its environment to decide how best to construct itself within the parameters of its genes.”

Stress is an example of how a fetus responds to stimuli in the womb and adapts physiologically. “When the mother is stressed, several biological changes occur, including elevation of stress hormones and increased likelihood of intrauterine infection,” Dr. Wadhwa says. “The fetus builds itself permanently to deal with this kind of high-stress environment, and once it’s born may be at greater risk for a whole bunch of stress-related pathologies.”

Pre-term births and low birth weight are among the most recognized effects of maternal stress during pregnancy, established over nearly two decades of animal and human research. Recent studies by Dr. Wadhwa and colleagues suggest that women who experience high levels of psychological stress are significantly more likely to deliver pre-term. Typically, one in 10 women delivers pre-term (before 37 weeks).

Most recently, some studies are suggesting that stress in the womb can affect a baby’s temperament and neurobehavioral development. Infants whose mothers experienced high levels of stress while pregnant, particularly in the first trimester, show signs of more depression and irritability. In the womb, they also are slower to “habituate” or tune out repeated stimuli — a skill that, in infants, is an important predictor of IQ.

“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.”

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.

“I think our whole approach to comprehensive prenatal care today is sort of messed up — a lot of the focus is on the wrong things,” says Dr. Hobel. “We measure a woman’s blood pressure, her uterine size, listen to the baby’s heart tones, but no one asks how things are going with her life.”

The big question, he says, is finding the right interventions. He and Dr. Dunkel-Schetter believe some of those components include the usual methods to reduce stress, including biofeedback, guided imagery and yoga. But what may be equally important are a woman’s support network and providing enough information about prenatal care and the pregnancy to ward off worries.

And it’s clearly a matter of teaching women how to relax, a foreign concept for many. “No one is telling them that they should look at what they’re doing,” says Dr. Hobel. It might mean taking Wednesdays off and work Saturdays instead, just to break the fatigue of a week’s work; or making sure to take time for breakfast and frequent meals.

“Sure, I think there are some super women that can deal with stress, but if you really study them, you’ll recognize that they’ve got some built-in mechanisms, something about the way they’re dealing with their lives, that makes a difference,” says Dr. Hobel. “Pregnancy itself is a real stress on the body.”

Dr. James McGregor, a professor of obstetrics at the University of Colorado Health Sciences Center, uses another type of test to predict pre-term labor. It’s a saliva test that measures another hormone, estriol, which can give up to three-weeks notice of the onset of labor. He’s even called employers when it indicates a patient needs to kick back a little.

Sometimes, he says, it’s hard to persuade pregnant women themselves that they may need to slow down if they’re feeling stressed. “Actually everybody knows it, but we kind of deny it,” says Dr. McGregor. “Stress comes under the heading of an old wives’ tale, but in this case, it happens to be true.”

What Is Your Stress Level?

Here are some questions to assess your level of stress during pregnancy, developed by Dr. Calvin Hobel, director of maternal-fetal medicine at Cedars Sinai Medical Center in Los Angeles. For each question, answer “yes,” “sometimes” or “no.” If you answer “sometimes” or “yes” to three or more questions, says Dr. Hobel, you may have sufficient stress to warrant some form of counseling or intervention. Consult your health-care provider.

• I feel tense.
• I feel nervous.
• I feel worried.
• I feel frightened.
• I have trouble dealing with problems.
• Things are not going well.
• I cannot control things in my life.
• I am worried that my baby is abnormal.
• I am concerned that I may lose my baby.
• I am concerned that I will have a difficult delivery.
• I am concerned that I will be unable to pay my bills.
• I live apart from my partner or spouse.
• I have extra-heavy homework.
• I have problems at work.
• Have you and your partner or spouse had any problems?
• Have you been threatened with physical harm?

Learning From Inside the Womb
How developing babies acquire skills before birth

by Annie Murphy Paul | July 29, 2011

When does learning begin? It’s a deceptively simple question. The answer that springs to mind may be the first day of preschool or kindergarten: the first time kids are in a classroom with a teacher. Or perhaps you’ve called to mind the toddler phase, when children are learning to walk, and talk, and eat with a fork. Maybe you’ve encountered the “Zero to Three” movement, which asserts that the most important years for learning are the earliest ones, so your answer to the question would be: Learning begins at birth.

The correct answer may surprise you. You may even find it implausible — though it’s supported by the latest research from biology and psychology. And that is that some of the most important learning we ever do happens before we’re born, in the womb. When we hold our babies for the first time, we might imagine that they are clean slates, unmarked by life — when in fact they have already been shaped by us, and by the particular environments we live in.

First of all, they learn the sound of their mothers’ voices. Because sounds from the outside world have to travel through the mother’s abdominal tissue and through the amniotic fluid that surrounds the fetus, the voices fetuses hear, starting around the fourth month, are muted and muffled. One researcher says that they probably sound a lot like the voice of Charlie Brown’s teacher in the Peanuts cartoons. But the pregnant woman’s own voice reverberates through her body, reaching the fetus much more readily, and because the fetus is always with her, it hears her voice a lot. Once it’s born, it recognizes the sound of her voice, and it prefers listening to her voice over anyone else’s.

How can we know this? Newborn babies can’t do much, but one thing they’re really good at is sucking. Researchers in these experiments rigged up a pair of rubber nipples so that if the baby sucks on one, it hears a recording of its mother’s voice through a pair of headphones. If it sucks on the other nipple, it hears the voice of a female stranger. Babies quickly make their preference known by choosing the first one.

In these studies, scientists also take advantage of the fact that babies will slow down their sucking when something interests them, and they’ll resume their fast sucking when they get bored. This is how researchers discovered that, after women repeatedly read aloud a section of Dr. Seuss’s The Cat in the Hat while they were pregnant, their newborn babies recognized that passage when they heard it outside the womb.

My favorite experiment of this kind is the one that showed that the babies of women who watched a certain soap opera every day while they were pregnant recognized the theme song of that show once they were born. Fetuses are even learning about the particular language spoken in the world that they’ll be born into. A study published last year reported that, from birth, babies cry in the accent of their mothers’ native language. French babies’ cries end on a rising note, while German babies’ end on a falling note — imitating the “melodic contours” of those languages.

Why would this kind of fetal learning be useful? It may have evolved to aid the baby’s survival. From the moment of birth, the baby responds most to the voice of the person who is most likely to care for it — its mother. It even makes its cries sound like the mother’s language, which may further endear the baby to the mother, and may give the baby a head start in the critical task of learning to understand and speak its native language.

But it’s not just sounds that fetuses are learning about in utero. It’s also tastes and smells. By seven months of gestation, the fetus’s taste buds are fully developed, and its olfactory receptors, which allow it to smell, are functional. The flavors of the food a pregnant woman eats find their way into the amniotic fluid, which is continuously swallowed by the fetus. Babies seem to remember, and prefer, these familiar tastes once they are out in the world.

In one experiment, a group of pregnant women was asked to drink a lot of carrot juice during their third trimesters, while another group of pregnant women drank only water. Six months later, the women’s infants were offered cereal mixed with carrot juice, and their facial expressions were observed while they ate. The offspring of the carrot juice-drinking women ate more carrot-flavored cereal, and from the looks of it, they seemed to enjoy its taste more.

A French version of this experiment was carried out in Dijon, France, where researchers found that infants whose mothers consumed food and drink made with licorice-flavored anise during pregnancy showed a preference for anise on the days they were born, and again when they were tested later, on their fourth days of life. Babies whose mothers did not eat anise during pregnancy showed a reaction that roughly translates as “Yuck.” What this means is that fetuses are effectively being taught by their mothers about what is safe and good to eat. Fetuses are also being taught about the particular culture they’ll be joining, through one of culture’s most powerful expressions: food. They’re being introduced to the characteristic flavors and spices of their culture’s cuisine even before birth.

Now, it turns out that fetuses are learning even bigger lessons. But before we get to that, let’s address something you might be wondering about.

The notion of fetal learning may conjure up for you attempts to enrich the fetus, like playing Mozart through headphones placed on a pregnant belly. Actually, the nine-month-long process of shaping and molding that goes on in the womb is a lot more visceral and consequential than that. Much of what a pregnant woman encounters in her daily life — the air she breathes, the food and drink she consumes, the chemicals she’s exposed to, even the emotions she feels — are shared in some fashion with her fetus. They make up a mix of influences as individual and idiosyncratic as the woman herself. The fetus incorporates these offerings into its own body, makes them part of its flesh and blood. And, often, it does something more: it treats these maternal contributions as information, as biological postcards from the world outside.

So what a fetus is learning about in utero is not Mozart’s “Magic Flute,” but the answers to questions much more critical to its survival: will it be born into a world of abundance, or scarcity? Will it be safe and protected, or will it face constant dangers and threats? Will it live a long, fruitful life, or a short, harried one? The pregnant woman’s diet and stress level, in particular, provide important clues to prevailing conditions, like a finger lifted to the wind. The resulting tuning and tweaking of the fetus’s brain and other organs are part of what give us humans our enormous flexibility, our ability to thrive in a huge variety of environments, from the country to the city, from the tundra to the desert.

One good example that illustrates this occurred in the autumn of 1944, the darkest days of World War II, when German troops blockaded western Holland, turning away all shipments of food. The opening of the Nazis’ siege was followed by one of the harshest winters in decades, so cold the water in the canals froze solid. Soon food became scarce, with many Dutch surviving on just 500 calories a day, a quarter of what they consumed before the war. As weeks of deprivation stretched into months, some resorted to eating tulip bulbs. By the beginning of May, the nation’s carefully rationed food reserve was completely exhausted. The specter of mass starvation loomed — and then, on May 5, 1945. the siege came to a sudden end, when Holland was liberated by the Allies.

The Hunger Winter, as it came to be known, killed some ten thousand people and weakened thousands more. But there was another population that was affected: the 40,000 fetuses in utero during the siege. Some of the effects of malnutrition during pregnancy were immediately apparent in higher rates of stillbirths, birth defects, low birth weights, and infant mortality. But others would not be discovered for many years. Decades after the Hunger Winter, researchers documented that people whose mothers were pregnant during the siege have more obesity, more diabetes, and more heart disease in later life than individuals who were gestated under normal conditions. These individuals’ prenatal experiences of starvation seem to have changed their bodies in myriad ways: they have higher blood pressure, poorer cholesterol profiles, and reduced glucose tolerance, a precursor of diabetes.

Why would undernutrition in the womb result in disease later? One explanation is that fetuses are making the best of a bad situation. When nutrients are scarce, they divert nutrients towards the really critical organ — the brain — and away from other organs, like the heart and liver. This keeps the fetus alive in the short term, but the bill comes due later in life when those other organs, deprived early on, become more vulnerable to disease.

But that may not be all that’s going on. It seems that fetuses are taking cues from the intrauterine environment and tailoring their physiology accordingly. They’re preparing themselves for the kind of world they will encounter on the other side of the womb. The fetus adjusts its metabolism and other physiological processes in anticipation of the environment that awaits it. And the basis of the fetus’s prediction is what its mother eats. The meals a pregnant woman consumes constitute a kind of story, a fairytale of abundance or a grim chronicle of deprivation. This story imparts information that the fetus uses to organize the body and its systems, an adaptation to prevailing circumstances that facilitates its future survival. Faced with severely limited resources, a smaller-sized child with reduced energy requirements will, in fact, have a better chance of living to adulthood.

The real trouble comes when pregnant women are, in a sense, unreliable narrators: when fetuses are led to expect a world of scarcity and are born instead into a world of plenty. This is what happened to the children of the Dutch Hunger Winter, and their higher rates of obesity, diabetes, and heart disease are the result. Bodies that were built to hang on to every calorie found themselves swimming in the superfluous calories of the postwar Western diet. The world they had learned about while in utero was not the same as the world they were born into.

We’ve also seen instances in our lifetimes when mother’s narrations have, in a sense, prepared their children for the world they would be born into. At 8:46 AM on September 11, 2001, there were tens of thousands of people in the vicinity of the World Trade Center — commuters spilling off trains, waitresses setting tables for the morning rush, brokers already working the phones on Wall Street. About 1,700 of these people were pregnant women. When the planes struck and the towers collapsed, many of these women experienced the same horrors inflicted on other survivors of the disaster: the overwhelming chaos and confusion, the rolling clouds of potentially toxic dust and debris, the heart-pounding fear for their lives.

A year after 9/11, researchers examined a group of women who were pregnant when they were exposed to the World Trade Center attack. In the babies of those women who developed post-traumatic stress syndrome, or PTSD, following their ordeal, researchers discovered a biological marker of susceptibility to PTSD — an effect that was most pronounced in infants whose mothers experienced the catastrophe in their third trimesters. In other words, the mothers with post-traumatic stress disorder had passed on a vulnerability to the condition to their children while they were still in utero.

Now, consider this: Post-traumatic stress syndrome appears to us to be a reaction to stress gone very wrong, causing its victims tremendous unnecessary suffering. But there’s another way of thinking about PTSD. What looks like pathology to us might actually be a useful adaptation in some circumstances. In a particularly dangerous environment, the characteristic manifestations of PTSD — a hyperawareness of one’s surroundings, a quick-trigger response to danger — could save someone’s life. The notion that the prenatal transmission of PTSD risk is adaptive is still speculative — but if true, it would mean something rather poignant. It would mean that even before birth, mothers are warning their children that it’s a wild world out there, telling them: Be careful.

Let’s be clear: Research on fetal learning is not about blaming women for what happens during pregnancy. It’s about discovering how best to promote the health and well-being of the next generation. That important effort must include a focus on what fetuses learn during the nine months they spend in the womb.

Learning is one of life’s most essential activities, and it begins earlier than we ever imagined.

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