Moderator: From the Eunice Kennedy Shriver National Institute of Child Health and Human Development, part of the National Institutes of Health, welcome to NICHD Research Perspectives. Your host is the Director of the NICHD, Dr. Alan Guttmacher.
Dr. Alan Guttmacher: Hello, I'm Alan Guttmacher, Director of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, or NICHD, which is part of the National Institutes of Health, or NIH. Thanks for joining us for the first of our new monthly podcast series in which we meet with NICHD researchers to discuss recent interesting NICHD research. We have with us today from the NICHD staff: Dr. Peggy McCardle, Dr. Katherine Laughon, and Dr. Marc Bornstein. As usual, it's been a very productive few weeks at the NICHD, and today we have several fascinating areas of research to discuss with these three folks.
First, we'll talk about the natural advantages that bilingual children apparently have when switching tasks; then, the length of time pregnant women spend in labor today as compared to 50 years ago; and finally, whether the adult brain is somehow predisposed to care for small children. First, we'll talk with Peggy McCardle who is the Chief of the Child Development and Behavior Branch in the extramural program at the NICHD. The Extramural Program supports research conducted by researchers in universities and other facilities across the U.S. and even throughout the world. Her branch recently supported the study by Canadian researchers, which found that bilingual children switch more easily from one task to another than do children who speak only one language. Peggy, what does this finding say about how bilingualism affects brain development?
Dr. Peggy McCardle: Well, it basically tells us that bilingual children are more cognitively flexible—and better able to switch between different rules within the same type of task—more quickly and accurately than monolingual children and that that's true even for very different language combinations, like Spanish/English bilinguals or Chinese/English bilinguals. So it's telling us that having two languages in the brain is associated with being better able to multitask, if you will.
Dr. Alan Guttmacher: So as I understand it, bilingual children sort of carry with them two sets of rules. How do they toggle back and forth between those?
Dr. McCardle: Well, they actually have both languages active in their minds at the same time, so they do, as you said, have these two sets of language rules in mind; and depending on the circumstances and the language they're addressed in, they are able to pull those rules up and use them for responding.
Dr. Guttmacher: Does this tell us anything more general about child development? Does it change what we already know about child development in any way?
Dr. McCardle: Well, I think it's really important that it finally gives us evidence that children can benefit from speaking more than one language in terms of their future ability to adapt to different demands, to switch between tasks. So it's not just that they'll be able to talk to people in two different languages, but that they have this cognitive flexibility that is going to enhance their learning abilities and, you know, just give them a lot of benefits that monolinguals may not have.
Dr. Guttmacher: Do you have any idea what's going to happen to these differences that we see in bilingual kids as they grow into adulthood?
Dr. McCardle: Well, there's evidence both in children and in adults of this cognitive flexibility, so as long as the bilingualism is maintained, we've got every reason to believe that these differences will persist, and we know that these differences do correlate with later better achievement.
Dr. Guttmacher: OK. Marc, I see that you have a question you wanted to ask Peggy about this.
Dr. Marc H. Bornstein: Sure, I do. Knowing that bilingualism is on the ascent in the United States, I am wondering what the next steps are for this research.
Dr. McCardle: Well, I would hope at a basic level that this would stimulate some work to try to determine exactly what changes, what's going on in the brain when these two languages are both active, when one is being stimulated versus the other, and there's a lot of interest in plasticity of learning. And I think that looking at the optimal periods for learning, especially for language learning and bilingualism, should have some implications. We need to know what those optimal periods are, and that should have implications for when we start to teach second or additional languages to our children in this country. In many countries, they begin very early. We tend to wait until later in their education, and that could change based on this evidence.
Dr. Bornstein: Also, does this enhanced flexibility in mental gymnastics, if you will—of having two languages—have benefits beyond the ability just to speak two languages.
Dr. McCardle: It absolutely does, and that's really the gist of why they did this study: is to show that it's not just the languages; it's the executive functions or that higher level cognitive flexibility so it isn't tied just to language. And as I said, it does correlate with later learning achievements, these executive function advantages.
Dr. Bornstein: It suggests that we ought to promote, rather than discourage, dual and multi-language learning.
Dr. McCardle: Absolutely, and the researcher who headed this, Ellen Bialystok, likes to call bilingualism "exercise for the brain." I love that term.
Dr. Bornstein: Thanks.
Dr. Guttmacher: Thanks very much, Peggy, and thanks for also introducing the concept of neural or brain plasticity to the four of us because that clearly is such an interesting and important area of research where certainly so much more about how the brain truly is plastic and not just in early childhood but even later into life than we ever suspected before. So I'm sure we'll be talking more as the months go on about other developments with you in brain plasticity.
Next, we're going to talk with Katherine Laughon, who has been involved in an interesting study done here in NICHD's intramural program—that's the program that's carried on at the NIH itself—and was published this month. The study found that, on average, women take longer to give birth today than did women 50 years ago. Katherine is in NICHD's epidemiology branch and is the study's first author. Katherine, can you please describe what the study found?
Dr. Katherine Laughon: Sure. We compared labor patterns between a modern cohort of women in the early 2000s to one that was done about 50 years ago in the 1960s and found that for first-time mothers, the first stage of labor, which is the time it takes for the cervix to dilate before active pushing begins, was 2.6 hours longer compared to 50 years ago and labor was about 1½ to 2 hours longer for women who had previously had a baby. And in this modern cohort, women were a couple years older, had a higher body mass index, and their babies weighed more. And all of these factors are known to contribute to increased labor duration. However, even when we took these characteristics into account, labor was still longer nowadays.
Dr. Guttmacher: So you took into account the factors that you thought would partially explain this, but even taking those into account, you still saw this longer period. Can you speculate about what other factors might be involved?
Dr. Laughon: Well, one thing that we also know that slows labor down are epidurals, and certainly this is an accepted practice for pain relief, and this was much more common in our modern study—about 55 percent of women compared to 4 percent in the 1960s. However, epidurals only slow labor down around 40 to 90 minutes, so that only accounted for part of the increase. We believe there is a reasonable chance that some other aspect of delivery room practice is responsible for this increase. But what those factors are, we'll have to keep doing research to figure those out.
Dr. Guttmacher: That's very interesting. Do you have any thoughts about how this research might affect current delivery practices?
Dr. Laughon: Since our previous understanding of a normal labor duration came from studies in the 1950s, and we now know that labor is longer and the population of women is very different from the population back then, a physician may opt to give a woman more time before speeding up the pace of labor with oxytocin or before intervening and performing a cesarean section.
Dr. Guttmacher: Based on this research, could you give any advice to a specific individual or a pregnant woman at this point?
Dr. Laughon: You know, as I said, more research is needed to determine what factors are causing labor to be longer. But, we always encourage women to have an open discussion with their physician or midwife—in particular, women who are overweight or obese or who would like to become pregnant and would like to become pregnant should speak with their health care provider about losing weight before becoming pregnant to improve chances for a healthy labor and delivery.
Dr. Guttmacher: Sounds like good advice. Dr. McCardle, I see that you have a couple of questions.
Dr. McCardle: Yeah, Katherine, does this cause you to want to redefine—do you think we're going to redefine what we think of as normal labor periods?
Dr. Laughon: I do. You know we've previously found that one out of three first-time mothers had a cesarean section, which is an astonishing statistic. What's important to keep in mind is that the indication for a large number of cesarean sections was because labor was diagnosed as not progressing normally, when in reality, women maybe simply need more time to deliver than they used to. So I do think we need to revisit our clinical definitions.
Dr. McCardle: Now you've pointed out several areas that need more research. What do you think is the most important next step? Which part of that do you want to do next?
Dr. Laughon: What we've done today is to really describe the overall patterns of labor, including what is average and what's at the extremes. However, we know that labor patterns are unique. One woman may progress a lot faster than another woman. Our ultimate goal is to be able to predict the expected labor pattern for a particular woman in labor so that her health care provider can know what is normal or abnormal for her and deliver individualized care.
Dr. McCardle: So that the woman might better know what to expect as well.
Dr. Laughon: Exactly.
Dr. McCardle: That's great.
Dr. Guttmacher: Katherine, I assume that this study was done on women in the U.S. Can you tell us anything about regional differences in the U.S., or do you have any idea how period of labor in the U.S. might compare to that in other countries?
Dr. Laughon: We haven't compared to other countries. This cohort was a large study of over 200,000 women at 12 sites in 19 hospitals around the country. It was a mix of different types of hospitals, but we haven't compared regional differences yet.
Dr. Guttmacher: OK, thanks. That's a very interesting study. And our third guest, Marc Bornstein, who you already heard ask a couple of questions earlier, he's the head of the child and family research section, also in the intramural program here at NICHD, was a member of the research team who conducted a very interesting recent study, which tells us something perhaps about the predisposition of folks to care for small children. So Marc, what can you tell us about the study, and what did it find?
Dr. Bornstein: Well, I'd like to tell you about it, with some pleasure. Our study was pretty straightforward. We showed people pictures of faces of infants and adults, of animals and humans. So we had babies and kittens as well as adults and dogs. And people were in the scanner at this time in an FMRI situation; the functional magnetic residence imaging is a noninvasive technique that gives those beautiful pictures we see of which parts and regions of the brain are active during a task or on presentation of different kinds of stimulation. And what we found was three main results for heightened activity to human infant faces in comparison with adult faces of animals or humans or even infant animal faces. One result was more activity in an area called supplementary motor area, the SMA, which is concerned with the preparation to move or to speak. It calls the, so to speak, readiness potential for intentional planning, and it's the starting mechanism for vocal tract movements or for beginning to speak.
A second area that was excited specifically by human infant faces was the fusiform gyrus, an area that's known to be sensitive to faces, so infant faces showed an enhanced attention in that area. And a third was two regions were older areas of the brain, the thamalus and the cingulus which have been associated with emotion, with empathy, and with arousal. So we conclude from these results that human infant faces are special in their stimulus and in their reward value, in the sense that they capture attention and that they prompt care. That is, just looking at a baby seems to get us ready to move and to speak. It heightens our attention and is associated with reward, and these were nonparents, so even in people who don't have babies, this is a general kind of result.
Dr. Guttmacher: What kinds of implications might these findings have for future research on caregiver behavior?
Dr. Bornstein: Well, one of the things they do is confirm the importance of responsiveness to infants. We know from an evolutionary perspective, responding to babies has vital implications for infant survival, but also modern developmental science tells us that caregiver responsiveness to infants promotes infants' appropriate social development, verbal and language development, and cognitive development. Now, in terms of future kinds of implications for caregiving, at a group level, there are two groups in which responsiveness is generally found to be compromised. One is adolescent mothers, and unhappily, as we know, the U.S. leads the industrialized world in teen pregnancies. And the second is in depressed mothers in whom responsiveness is typically muted, and about 12 percent of births in the United States are to depressed parents, so it's important to know about this kind of responsiveness with respect to these subgroups.
Dr. Guttmacher: Marc, you mentioned the mothers. Did the study say anything about substantial differences between men and women?
Dr. Bornstein: We studied both men and women; in our study, there were no differences between men and women in responding. But this study joins a growing literature on what I'll call the parent brain, if you will, which shows some similarities and some differences depending upon which kind of stimulus is used, what the task is, and what regions of the brain are being explored. One follow-up study we've done now that shows gender differences is to look at adults' reactions to infant cry. Like infant faces, infant cries are very potent stimuli, as we know. And what we found was that female brains show greater planning and empathy kinds of responses to the hunger cry, and that was true again, regardless of parenthood status. And they showed greater responses than male brains.
Dr. Guttmacher: Given these findings, you already mentioned one follow-up study that you've kind of done. Where do you see research in this topic heading in the future?
Dr. Bornstein: Well, as I just eluded, as you mentioned, one direction is to examine different kinds of special populations—adolescent parents and depressed parents. One could also look at abusing and neglectful parents, and a second direction of future research looks at different kinds of child-related stimuli, like cries as I mentioned; but also one might look at positive responsiveness to babbling or to look at images of children in danger relative to this propensity to move and respond to children and infants that way. I think it's important to remember, Dr. Guttmacher, that every person alive has been reared by a parent of one kind or another. So we really can't overestimate the significance to life or child development of parenting and parent-provided experience.
Dr. Guttmacher: Dr. Laughon, I see that you've got a question for Marc.
Dr. Laughon: I do. You mentioned that one area to go is to do future research on child abuse or neglect. Can you be more specific about this?
Dr. Bornstein: Yeah, I think our results are directly related to that kind of compromise. Recall that we found heightened activation in that region of the brain, the SMA, the supplementary motor area, to infant faces. That was also true of infant cries, by the way. The SMA is associated with getting ready to act or to speak. One could think of neglect as the opposite, OK? So it could be that individual differences in neglect are associated with or a product of altered brain functions, and we happen to be working currently on recruiting a court sample that would help us test this hypothesis. So in a nutshell, neglect may be some kind of hyposensitivity—reduced sensitivity—of those parts of the brain; and abuse, on the other side, may be hypersensitivity—being really strongly responsive to the infant cry, which elicits a different kind of response on the part of adults.
Dr. Guttmacher: Well with that, we come to the end of our podcast for this month. I'd like to thanks Dr. McCardle, Dr. Laughon, and Dr. Bornstein for joining us and to thank you, our listeners, as well. If you'd like more information about these topics and many related ones, you can go to the Web and visit nichd.nih.gov, and you'll find lots of information. I'm Alan Guttmacher and I hope you'll join us for more of our podcast from NICHD as they are posted each month.
Moderator: This has been NICHD Research Perspectives, a monthly podcast series hosted by Dr. Alan Guttmacher. If you have any questions or comments, please email NICHDInformationResourceCenter@mail.nih.gov.
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