Throughout its history the NICHD has sponsored longitudinal studies to better comprehend key factors that influence human health and development at various points across the lifespan. NICHD-sponsored studies evaluate a broad range of subjects and populations, from gauging the impact of early child care to analyzing factors that influence fertility. Descriptions of some of the Institute's longitudinal studies are available below.
Early Childhood Longitudinal Study-Birth Cohort
The Early Childhood Longitudinal Study (ECLS) includes three longitudinal studies that examine child development, school readiness, and early school experiences.
The birth cohort of the ECLS (ECLS-B) is a nationally representative sample of approximately 14,000 children born in 2001 and followed from birth through kindergarten entry. The children participating in the study came from diverse socioeconomic and racial/ethnic backgrounds with an oversampling of Chinese children, other Asian and Pacific Islander children, American Indian and Alaskan Native children, twins, and children born with low and very low birth weight.
Information about these children was collected when they were approximately 9 months old, 2 years old, and 4 years old/preschool age. Researchers queried children, parents, child care providers, and teachers on children's cognitive, social, emotional, and physical development.
Federal collaborators in the ECLS-B included several components of the U.S. Department of Education and a number of components of the U.S. Department of Health and Human Services, including the National Center for Health Statistics, NICHD, and a number of other NIH Institutes.
Fels Longitudinal Study (FLS) of Physical Growth and Development
The FLS is the largest and oldest longitudinal study of growth and development in the world, following more than 1,500 individuals from birth since 1929.
In 1976, NICHD began funding the FLS and using the data for numerous studies, including many on the early onset of cardiovascular risk factors in children and adults. One study used the FLS to evaluate the relationship between childhood/ adolescent adiposity and adult obesity. The results revealed that the earlier in life individuals become overweight, the more serious their risk factors were for obesity and heart disease in adulthood. Investigators found a strong correlation between changes in Body Mass Index during childhood and adult overweight status in the same individuals at 35 to 45 years of age.
Data from the FLS continues to be used to study the importance of various childhood factors such as the effects of rapid or delayed puberty on the development of metabolic syndrome, cardiovascular disease, and type 2 Diabetes later in life.
Longitudinal Investigation of Fertility and the Environment (LIFE)
The LIFE Study was designed to examine the relation between ubiquitous environmental chemicals, lifestyle, and human fertility. The primary exposures of interest included persistent chemicals (e.g., PCBs, PBDEs and PFOS) and lifestyle factors (e.g., stress, cigarette smoking, caffeine, and alcohol usage).
The LIFE Study followed approximately 800 couples in two states as they tried to become pregnant for up to 12 menstrual cycles. Women who conceived were followed through delivery. Primary outcome measures included fecundity (probability of being pregnant in a single menstrual cycle), pregnancy loss, infertility, and infant gestation and birth size.
National Longitudinal Study of Adolescent to Adult Health (Add Health, formerly the National Longitudinal Study of Adolescent Health)
The Add Health Study is a nationwide survey implemented to examine how social contexts such as peer groups and communities impact adolescent health. The study started in 1994 under a grant from the NICHD and was co-funded by 17 other federal agencies. It is the largest, longitudinal sampling of adolescents ever undertaken.
Starting in 1994, researchers chose a random sampling of 90,000 7th to 12th graders to answer a short questionnaire. The researchers made every effort to ensure that the study cohort was demographically representative of the U.S. population. After sifting through the results, researchers conducted around 20,000 in-depth home interviews with selected study participants. The researchers continued to conduct follow-up interviews as the participants progressed through high school into early adulthood. To provide context, researchers analyzed existing data on the participant's communities and interviewed or sampled school administrators, classmates, parents, siblings, and romantic partners.
Among its many findings, the study found that adolescents who feel a strong and secure personal relationship to their communities are far less likely to engage in risky behaviors such as smoking, drug abuse, unprotected sex, and violence. Inversely, adolescents living in homes where drugs, tobacco, or alcohol are present are more likely to engage in risky and unhealthy behaviors.
NICHD Study of Early Child Care and Youth Development (SECCYD)
In 1991, the NICHD initiated the Study of Early Child Care (SECC), which eventually came to be known as the Study of Early Child Care and Youth Development (SECCYD). This comprehensive, longitudinal study included more than 1,500 children and their families.
The study sought to examine the relationship between child care experiences and developmental outcomes. The children's development was analyzed over four phases:
- Phase 1 comprised infancy.
- Phase 2 monitored the group through first grade.
- Phase 3 followed them through sixth grade.
- Phase 4 saw the study through the ninth grade.
The study sought to answer myriad questions about how early childcare influences development outcomes. For example: how did development outcomes for children who were cared for primarily by their mothers differ from those in non-maternal care? Or how did different demographic and social backgrounds influence childcare choices? While the study found linkages between the quality of childcare and effective development, family factors such as parent's education, income level, psychological adjustment and sensitivity ultimately proved the most influential.
To learn more about the SECCYD, visit the SECCYD webpage.
Science and Ecology of Early Development (SEED)
The SEED program supports research focused on the mechanisms through which social, economic, cultural, familial, and community-level factors impact the early cognitive, neurobiological, socio-emotional, and physical development of children.
Understanding these mechanisms is especially important to evaluate the impact of services and public policies on the development of children and their families, especially those living at or near the federal poverty line.
Specific topics of interest include childcare, early childhood education, welfare reform, tax structure, social services, and work-family policies, since all of these factors shape the life experiences of children in poverty. The program seeks to generate solid scientific information, which inform policies and deliver programs aimed at supporting child development in lower income communities.