Previously Featured Publications
This is a small selection of publications on Project Viva research. For a more comprehensive list please click here.
Due to copyright issues, we are not able to post copies of the published articles. If Viva participants would like a copy of the article, please email us, Project_Viva@hphc.org.
Prospective Association between Milk Intake and Adiposity in Preschool-Aged Children
The American Academy of Pediatrics and the American Heart Association are trying to curb America’s obesity epidemic in children by recommending children 2 years or older switch from drinking whole milk to reduced fat milk. Despite these recommendations, few studies have actually investigated whether drinking low fat milk is associated with a decreased weight in children at this age. Project Viva investigators looked at the quantity and type of milk consumed at 2 years of age to determine whether it is associated with overweight at 3 years of age. We analyzed 852 Viva kids’ food and dairy intake at age 2 through food questionnaires completed by Viva moms and compared it to measured heights and weights at age 3. In the analysis, factors such as mother’s BMI and education; father’s BMI; and child’s age, sex, race/ethnicity, intake of energy, intake of non-dairy beverages, and television viewing were considered. We did not find an association between intake of full milk, reduced fat milk, total milk, or total dairy and overweight at age 3. It appears that neither consuming more dairy products nor switching from whole milk to reduced fat milk at age 2 is likely to prevent overweight in early childhood.
Huh SY, Rifas-Shiman SL, Rich-Edwards JW, Taveras EM, Gillman MW. Prospective association between milk intake and adiposity in preschool-aged children. J Am Diet Assoc. 2010 Apr;110(4):563-70.
Television Viewing in Infancy and Child Cognition at 3 Years of Age in a US Cohort
Since 1999 the American Academy of Pediatrics has recommended no screen media for children under 2 years of age. It is estimated that an average of 68% of children younger than two years of age use screen media on a typical day and twenty five percent of these children have a TV in their bedrooms. Many parents believe that TV helps their infants learn, but there is little evidence of any benefits of TV viewing on children younger than 2 years of age.
Researchers examined which television viewing is associated with language and visual motor skills at 3 years of age. 872 children were surveyed for how much TV they watched in a 24 hour period at 6 months, 1 year and 2 years of age. Average TV viewing from birth to two years was 1.2 hours, this value is less than other research studies of this age group. Findings indicated that each additional hour of TV watched was not associated with language or visual motor abilities at age 3.
Although TV viewing between birth and 2 years of age was not shown to hinder nor benefit child cognitive and language abilities, there are some known benefits to limiting your child’s exposure to television in early childhood. For example, other studies have shown that with limited TV exposure improves sleep and diet quality and lowers the risk of a child becoming overweight or obese.
Schmidt ME, Rich M, Rifas-Shiman SL, Oken E, Taveras EM. Television viewing in infancy and child cognition at 3 years of age in a US cohort. Pediatrics; 2009 Mar;123(3):e370-5.
Early Child Care and Adiposity at Ages 1 and 3 Years
Most infants in the United States are in a non-parental child care and little is known about the effect of child care on the development of obesity. Researchers studied 1138 children and found that 57% of these spent some time in child care from birth to 6 months of age. Children were divided into three groups based on their type of care. 17% of infants spent time in a child care center, 27% spent time in someone else’s home, and 21% were cared for in their own home by someone other than a parent. Children that had some kind of child care arrangement were breastfed for shorter durations, were more likely to be black or Hispanic/Latino and were more likely to come from families with incomes greater than $70,000 per year. Researchers found that more hours spent in child care in someone else’s home during the first 6 months was associated with increased measures of adiposity at ages 1 and 3. Neither center-based child care nor care in the child’s own home by a non-parent was related to the adiposity outcomes. With so many children spending a large majority of their infancy and pre-school years in childcare, it is important to consider what happens during that time that may contribute to the development of childhood obesity.
Benjamin SE, Rifas-Shiman SL, Taveras EM, Haines J, Finkelstein J, Kleinman K, Gillman MW. Early child care and adiposity at ages 1 and 3 years. Pediatrics. 2009 Aug;124(2):555-62. Epub 2009 Jul 27.
Associations of diet and physical activity during pregnancy with risk for excessive gestational weight gain.
Mothers who gain excessive weight during pregnancy are more likely to deliver by cesarean section, develop preeclampsia, retain excess weight after delivery, and become overweight or obese later in life. Infants that are born to women who gain weight excessively during pregnancy are more likely to be born preterm, weigh over 9 pounds at birth, and become obese as toddlers, adolescents or adults themselves. Researchers assessed 1388 women in this study and found that 379 women were overweight at pregnancy while 703 experienced excessive weight gain during their pregnancy. Researchers then explored associations of diet and exercise on excessive weight gain in Project Viva. They found that excessive weight gain was slightly more common among younger women between the ages of 25 and 30 and less common among women older than 35 years. They also saw that BMI before pregnancy, race, smoking status, and nausea in the first trimester were all independently related to excessive weight gain during pregnancy. Vegetarian diet, exercise, and an active lifestyle were linked to a lower risk of excessive weight gain. Future intervention studies that target these behaviors could provide more information on whether beneficial changes influence weight gains and improve maternal and child health outcomes.
Stuebe AM, Oken E, Gillman MW. Associations of diet and physical activity during pregnancy with risk for excessive gestational weight gain. Am J Obstet Gynecol. 2009 Jul;201(1):58.e1-8.
Associations of Gestational Weight Gain With Short- and Longer-term Maternal and Child Health Outcomes
The amount of weight a mother gains while pregnant is an important indicator of both the immediate and lifelong outcomes of pregnancy. The Institute of Medicine currently recommends that women with a normal body mass index (BMI) gain 11.5 to 16.0kg, overweight women gain 7.0-11.5kg, and obese women gain at least 6kg. Some experts are concerned that these recommendations are too high, and provide little guidance about weight gain for women. One third of women of childbearing age are obese, and so it is important to minimize the negative outcomes of pregnancy. The present study used longitudinal data from Project Viva to examine a pre-birth cohort of mothers and children for such risks as preterm delivery, maternal post partum weight retention, and the development of childhood obesity. Among all women in this study, gestational weight gain was directly associated with the risk of substantial postpartum weight retention and development of child obesity. In order to reduce the prevalence of the adverse outcomes observed, results of this study recommend a gain of 11.2kg for women of a normal weight, a loss of 1.2kg for overweight women, and a loss of 7.6kg for obese women during their gestation. These results suggest that weight gain recommendations for overweight and obese women should be lowered to avoid the adverse health outcomes that may result for women and their children.
Oken E, Kleinman KP, Belfort MB, Hammitt JK, Gillman MW. Associations of gestational weight gain with short- and longer-term maternal and child health outcomes. Am J Epidemiol. 2009 Jul 15;170(2):173- 0.
Developmental Origins of Childhood Overweight: Potential Public Health Impact
Researchers have identified several maternal and infant risk factors for childhood overweight, but most studies analyze one risk factor independent of other known risk factors. In this study, we wanted to look at how the combinations of several risk factors influence overweight in childhood. We chose to examine four risk factors that have been identified in previous research to be modifiable and related to obesity and overweight in children. We chose excessive weight gain during pregnancy, reduced breast feeding duration, shortened sleep duration, and smoking during pregnancy. Our researchers found that the predicted chance of becoming overweight in childhood was as low as 6 percent when all risk factors were favorable to as high as 29 percent when all four risk factors were unfavorable. These findings suggest that interventions to change or modify these factors could have a substantial impact on preventing childhood obesity and its resulting consequences of poorer health.
Gillman MW, Rifas-Shiman SL, Kleinman K, Oken E, Rich-Edwards JW, Taveras EM. Developmental origins of childhood overweight: potential public health impact. Obesity (Silver Spring). 2008 Jul;16(7):1651-6.
Vitamin D deficiency and asthma are common in New England. Although vitamin D has important effects on the immune system, which is related to infections and allergies, the relation of vitamin D with asthma is unknown. To investigate this topic, we studied 1,194 mother-child pairs in Project Viva. We measured maternal intake of vitamin D during pregnancy by questionnaire. By age 3, 186 children (16%) had recurrent wheeze. Compared with mothers with low levels of vitamin D intake, those with higher intakes (e.g., approximately 800 IU/day) were less likely to have a young child with recurrent wheeze. We observed the same results whether the vitamin D was from dietary sources (e.g., fortified milk, fish) or vitamin supplements. Our findings suggest - at least among women in New England - that higher maternal intake of vitamin D during pregnancy may decrease risk for recurrent wheeze in early childhood. We do not know yet if this will translate into lower risk of childhood asthma. If yes, increased maternal intake of vitamin D during pregnancy may become a new, safe, and inexpensive way to prevent childhood asthma. Doing a breathing test with Viva kids at age 7 will help us to answer this important question.
Camargo CA Jr, et al. Maternal intake of vitamin D during pregnancy and risk of recurrent wheeze in children at age 3 years. Am J Clin Nutr 2007;85(3):788-95.
Women who get more physical activity before and during pregnancy are less likely to develop diabetes during pregnancy
Diabetes during pregnancy, which has been on the rise in recent years, can cause problems during pregnancy such as birth trauma and stillbirth, and also increases both the mother's and child's later risk for developing diabetes. We studied whether physical activity before or during pregnancy could reduce a mother's risk for developing diabetes during pregnancy ("gestational diabetes"). Obstetricians at Harvard Vanguard screened mothers for gestational diabetes at about the 7th month of pregnancy by testing their blood sugar after they had a drink high in sugar. Among the 1805 Project Viva mothers studied, about 5% developed gestational diabetes. Mothers who participated in vigorous physical activities before pregnancy, such as jogging, swimming, cycling, or aerobic class, had a lower risk of developing gestational diabetes compared with mothers who did not do any vigorous activities. Mothers who reported doing at least light/moderate physical activities during early pregnancy, such as yoga, bowling, and stretching classes, also had a lower risk of developing gestational diabetes, whereas mothers who were sedentary during pregnancy (less than 30 minutes a day of any physical activity) had an increased risk. These results support advice for all women to participate in regular vigorous physical activity, and to continue at least light to moderate activity after becoming pregnant.
Oken E, et al. Associations of physical activity and inactivity before and during pregnancy with glucose tolerance. Obstetrics and Gynecology 2006;108:1200-07.
Currently used guidelines for weight gain during pregnancy were published in 1990, before the modern obesity epidemic had taken hold. These guidelines advise that women with a normal weight before pregnancy should gain 25-35 pounds throughout pregnancy, and women who are overweight before pregnancy should gain 15-25 pounds. We have known for some time that mothers who gain more weight while they are pregnant have babies with higher birth weights. However, it is not clear if higher weight gain during pregnancy has any effects on children after birth. In this study, we followed 1044 Project Viva mothers and their children for 3 years after birth. Approximately one-third of mothers were overweight before pregnancy, and about 10% of children were overweight at age 3 years. Half of all women gained more weight during pregnancy than is recommended, 35% gained weight in the recommended range, and 14% gained less weight than is recommended. Compared to children of mothers who had gained less than the currently recommended amount of weight, children of mothers who had gained either within the recommended range, or above, had about 4 times the risk of being overweight at age 3 years. Women with gain below the recommended range did not have any increase in birth complications such as having a baby born at low birth weight. We suggest that current recommendations for pregnancy weight gain should be reconsidered to help prevent childhood obesity.
Oken E, et al. Gestational weight gain and child adiposity at age 3 years. Am J Obstet Gynecol 2007;196(4):322.e1-8.
We have known for a long time that women who smoke while they are pregnant are likely to give birth to smaller babies. However, recent studies have suggested that children whose mothers smoked during pregnancy are actually more likely to be overweight in later life. To further investigate this topic, we studied 746 mothers and their children enrolled in Project Viva. About 70% of the mothers had never smoked, 20% had previously smoked but quit smoking before pregnancy, and 10% smoked in early pregnancy. At age 3 years, children of mothers who had smoked during pregnancy were heavier and had higher blood pressure, and had about twice the risk of being overweight, compared with children of mothers who had never smoked. Although we don't yet know how being exposed to smoking before birth causes obesity, these results give yet another reason why women should not smoke while they are pregnant.
There has been a debate whether factors associated with major depression apply in the case of depression during pregnancy and the months after delivery. In Project Viva, 9% of mothers experienced depression during mid-pregnancy, and 8% experienced depression postpartum. Women with a history of depression before pregnancy had four times greater risk of depression during pregnancy, and women who had prenatal depression were nearly seven times more likely to experience postpartum depression than women who were not depressed during pregnancy. Mothers with financial hardship and unwanted pregnancy were more likely to experience depression. Women with good social support from partners, family, or friends seemed protected from depression.
Asthma is one of the most common chronic diseases in children. In older children and adults, studies have shown that those who are overweight are more likely to have asthma-related symptoms. There are few studies examining whether higher birth weight is associated with asthma-related symptoms in early childhood. In this study we found that children with high birth weight were not more likely to have asthma-related (wheezing) symptoms at 2 years of age. However, exposure to cigarette smoking, having a family history of asthma, having older siblings, and being male were all associated with higher risk of asthma-related outcomes at age 2 years.
C-reactive protein (CRP) is a sensitive inflammatory marker in the blood currently used to predict cardiovascular risk. In the first of these two studies, we found that Viva mothers who had periodontitis (gum disease with bone loss) had elevated levels of CRP in early pregnancy. In the second study, high levels of CRP early in pregnancy were related to increased risk of delivering babies prematurely. Taken together, our findings are consistent with the hypothesis that chronic low-grade inflammation (such as in periodontitis) may raise CRP levels and cause preterm delivery. Measuring CRP in early pregnancy may help pre-natal care providers decide who is at risk for premature delivery, but more data are needed.
We have known that higher maternal calcium intake in pregnancy may help prevent pregnancy-related high blood pressure, and that higher calcium intake in childhood may help lower blood pressure levels in children. But what about a mother’s calcium intake during pregnancy and blood pressure in her child? This study is one of the first to address this question. We found that at 6 months of age, blood pressure was lower among Viva infants whose mothers had consumed higher amounts of calcium in mid-pregnancy. Interestingly, calcium supplements rather than calcium from foods seemed to be the key. Almost a third of Viva mothers took calcium supplements during pregnancy—in the form of Tums, for heartburn! This is not the end of the story, however. It is important for us to look at this question again when we have gathered blood pressure information on all of our Viva 3-year-olds, as blood pressure means more then than it does during infancy. If these results pan out in our 3-year-olds, making sure that pregnant women get enough calcium may help to prevent high blood pressure from developing in their children.
As the saying goes, “breast is best” for almost all infants. We are happy to report that over 80% of Viva moms breastfed their infants, at least for some time. In this study, we found that black and Hispanic mothers initiated breastfeeding at rates at least as high as their white counterparts, which is not what most other studies have found. Why the great success in Viva participants? One reason is the wonderful support that HVMA clinicians provide. Another is that many of the minorities in Viva are immigrants from other countries. Our results showed that no matter what the race or ethnicity, more immigrants initiated breastfeeding than US-born women. To improve breastfeeding rates across the US, the lesson from this study is that we need to figure out how to maintain whatever cultural beliefs and practices immigrants bring with them to this country.
Breastfed children have been found to have a lower risk of obesity as they grow up. One of the explanations for this protective effect of breastfeeding is that breastfed children may learn to self-regulate how much they eat and mothers might learn how to be more responsive to her child's hunger cues and have less controlling feeding practices. In this study we found that mothers who breastfed in early infancy and who breastfed for longer periods were less likely to report highly controllingfeeding practices when their children were 1 year of age.
TLR2 and TLR4 stimulation differentially induce cytokine secretion in human neonatal, adult and murine mononuclear cells
The immune system is our body’s way of fighting infection and allergies. We used to think that a baby’s immune system develops only after birth. But now we know that important aspects of the immune system are already established even before birth. How the immune system develops in an individual may increase or lower that person’s risk for developing asthma or allergies during childhood. In the 1st of these 2 studies, we found that cell-to-cell messengers called cytokines are related to nuclear factor kappa B, a regulatory factor inside umbilical cord blood cells that is involved in immune responses of the baby. In the 2nd study, we found that stimulating these cells in the lab with parts of bacteria we see in our every day lives changed what kind of chemicals the cells produce, possibly in a direction that could protect against allergies as the children grow up. Whether these remarkable changes right at birth truly influence the development of allergies or asthma is something we will examine as the Viva kids grow up.
Associations of seafood and elongated n-3 fatty acid intake with fetal growth and length of gestation: Results from a US pregnancy cohort
Several studies have suggested that a diet high in fish, and the n-3 (or "omega-3") fatty acids in fish and other seafood, may offer a number of health benefits including a lower risk of premature birth. For this project, we used information provided by over 2100 Project Viva participants. We found that women who ate more seafood during pregnancy had babies with slightly lower birth weight for the length of their pregnancy, but did not have a lower risk of premature birth. The 25% of Project Viva participants who ate the most fish and omega-3 fatty acids had babies that were approximately 90 grams (3 ounces) lighter at birth than the 25% of Viva participants who consumed the least omega-3 fatty acids. In the future, we plan to perform additional studies to learn whether the children of mothers who ate more fish and omega-3 fatty acids during pregnancy are smaller because they have less body fat, and thus might have a lower risk of becoming overweight later in childhood.
Experiments in animals have shown that animals fed a diet low in protein content during pregnancy have offspring with higher blood pressure. Few studies have examined this question in humans, and we published one of the first studies in a developed nation to examine whether pregnancy diet affects offspring blood pressure. Among Project Viva participants, we did not find any relationship between maternal dietary protein content during pregnancy and blood pressure in the children at age 6 months. This study showed how valuable Project Viva can be in answering important questions about nutrition during pregnancy.
A well-publicized January 2001 federal advisory recommended that pregnant women limit consumption of certain fish because of concerns about mercury contamination. We studied the effect of this advisory on fish intake by women enrolled in Project Viva. We found that women surveyed after the advisory reported consuming less dark meat fish, canned tuna and white meat fish, and ate approximately 1.4 fewer total fish servings per month after January 2001. Because fish may also contain healthy nutrients, such as omega-3 fatty acids, the public health implications of this decreased fish intake remain unclear.
A number of studies now suggest that exposures that occur before birth may increase one’s risk for later obesity. Higher birth weight is associated with higher body mass index (BMI), a measure of obesity, in later life. Additionally, lower birth weight is associated with later central obesity (a relatively large waist, or the “apple shape”), and increased risk for heart disease, high blood pressure, and diabetes. Prevention of obesity starting in childhood is critical, and may improve lifelong health.
Atopic dermatitis, or eczema, is a common, chronic, itchy allergic skin disease that usually starts in infancy and early childhood. We investigated factors that were associated with atopic dermatitis in the infants enrolled in Project Viva. 17% of infants in Project Viva had been diagnosed with atopic dermatitis in the first 6 months of life. African-American and Asian-American infants, infants born at later gestational ages, infants whose mothers or fathers had allergic disorders, particularly eczema, but also asthma and hay fever, and young males were all more likely to have eczema. Our findings suggest that genetic and environmental factors, as well as prenatal factors, may influence the development of eczema.
You may recall our measuring blood pressure on your child in the newborn nursery. Among about 1000 Project Viva babies, blood pressure level was higher in newborn infants of older mothers. We couldn’t explain this finding by the fact that older moms tend to have higher blood pressures themselves, or any other factor we measured. The bottom line, though, is that blood pressure in newborns doesn’t mean the same thing as blood pressure later in life. So mothers in their 30s and 40s should not worry about creating high blood pressure in their children.
The terrorist attacks on September 11, 2001 were the most traumatic national events in U.S. history. National surveys found elevated rates of posttraumatic stress disorder, distress, and major depression among Americans, especially those living in New York City. There is a theory that women exposed to stressful events during pregnancy might be more likely to deliver preterm. We examined whether Project Viva participants who were pregnant on September 11 had shorter pregnancies than Project Viva participants who had delivered in the year before the terrorist attacks. Contrary to expectation, we found that women pregnant on September 11 actually had longer pregnancies. Anecdotally, the obstetricians noted that many women felt a renewed commitment to family and a strengthened bond with their community in the months after September 11 – we speculate that this sense of gratitude or belonging may have outweighed the anxiety from the terrorist event, at least for Boston-area women who were far from the actual sites of the attacks.