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Healthy children who are underweight in the first 2 years of life continue with a lower-than-average body mass index and height-for-age through age 10, according to new research.

The association was most pronounced for girls, as well as for children with lower growth rates, write the authors of the prospective Canadian cohort study published in JAMA Network Open.

The findings “highlight the importance of preventing underweight in early life,” because this can have “lasting effects” in later childhood, senior author Jonathon L. Maguire, MD, from St Michael’s Hospital Pediatric Clinic, and the University of Toronto said in an interview.
 

Methods and results

The study recruited 5,803 healthy children, mean age 4.07 months, between February 2008 and September 2020 during well-child visits at clinics in The Applied Research Group for Kids! (TARGet Kids!) practice-based research network in Canada. The study’s exclusion criteria included a premature birth, or a health condition affecting growth.

The primary outcome of the study was the child’s age- and sex-adjusted weight, also known as the body mass index z score (zBMI), between the ages of 2 and 10 years.

At baseline, a total of 550 children (9.5%) were classified as underweight, based on the World Health Organization definition of zBMI less than –2. Underweight children were more likely to be younger, have lower birth weight, and to report Asian maternal ethnicity, the researchers observed.

The study found that, compared with children with normal weight, those who were underweight in the first 2 years had lower zBMI at ages 5 and 10 years (–0.49 and –0.39 respectively). This meant that at 10 years old, they were a mean of 1.23 kg lighter than 10-year-olds who had been normal weight at age 2 years.

Height-for-age z score (HAZ) was also lower for underweight 2-year-olds (–0.24), making them a mean of 0.68 cm shorter than normal-weight 2-year-olds. This difference was attenuated at age 5 years.

Growth rate modified the association of underweight with both zBMI and HAZ. Among children who were underweight in the first 2 years, those with lower growth rate had lower zBMI at 10 years (–0.64) compared with those with average (–0.38) or high growth rate (0.11). Similarly, children who were underweight and had a lower growth rate at age 2 years also a lower HAZ at age 10 years (–0.12), compared with those with average (0.02) or high growth rates (0.16). These effects were more pronounced in girls.
 

Increased health risks linked with chronic underweight

This study did not assess the reasons for early underweight, Dr. Maguire commented in an interview. But, he cited challenges with dietary transitions as a possible explanation.

“Considerable dietary changes happen around 2 years of age with increasing diversity of foods as children transition from primarily liquid foods to primarily solid foods,” he noted.

Asked for comment on the study, Colleen Spees, PhD, associate professor in the division of medical dietetics and director of Hope lab at the Ohio State University, Columbus, said that “at age 10, it’s not surprising to see a lower zBMI and height-for-age in those that were underweight at age 2 with poor growth trajectories.”

Although, this is the first study she is aware of to document these findings in a Canadian cohort, “the results align with what we know about low birth weight and underweight infants and children in terms of linear growth trajectories from child stunting studies,” Dr. Spees said.

She said child stunting, which is more common in less developed countries where children have lower birth weights and greater socioeconomic and environmental risk factors, is defined by the WHO as impaired linear growth with adverse functional consequences.

“In short, a chronic underweight status in infants and young children can lead to greater risk of malnutrition, vitamin and mineral deficiencies, decreased immune function, as well as physical growth and development issues,” she said. “Hence, the most recent 2020-2025 Dietary Guidelines for Americans now includes both pregnancy, breastfeeding, and the first 2 years of life (referred to as the “first 1,000 days”) in their recommendations.”

She added that, if caregivers are concerned about their child’s weight, they should consult with their pediatrician to rule out any medical issues. If no medical issues are identified, they should ask for a referral to a pediatric dietitian.

The study was funded by the Canadian Institute of Health Research. Dr Maguire reported receiving grants from the CIHR, Physician Services, Ontario SPOR Support Unit, and Dairy Farmers of Canada during the conduct of the study and nonfinancial support from DDrops outside the submitted work. Other authors of the paper reported receiving grants from various institutions. Dr. Spees reported no relevant disclosures.

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Healthy children who are underweight in the first 2 years of life continue with a lower-than-average body mass index and height-for-age through age 10, according to new research.

The association was most pronounced for girls, as well as for children with lower growth rates, write the authors of the prospective Canadian cohort study published in JAMA Network Open.

The findings “highlight the importance of preventing underweight in early life,” because this can have “lasting effects” in later childhood, senior author Jonathon L. Maguire, MD, from St Michael’s Hospital Pediatric Clinic, and the University of Toronto said in an interview.
 

Methods and results

The study recruited 5,803 healthy children, mean age 4.07 months, between February 2008 and September 2020 during well-child visits at clinics in The Applied Research Group for Kids! (TARGet Kids!) practice-based research network in Canada. The study’s exclusion criteria included a premature birth, or a health condition affecting growth.

The primary outcome of the study was the child’s age- and sex-adjusted weight, also known as the body mass index z score (zBMI), between the ages of 2 and 10 years.

At baseline, a total of 550 children (9.5%) were classified as underweight, based on the World Health Organization definition of zBMI less than –2. Underweight children were more likely to be younger, have lower birth weight, and to report Asian maternal ethnicity, the researchers observed.

The study found that, compared with children with normal weight, those who were underweight in the first 2 years had lower zBMI at ages 5 and 10 years (–0.49 and –0.39 respectively). This meant that at 10 years old, they were a mean of 1.23 kg lighter than 10-year-olds who had been normal weight at age 2 years.

Height-for-age z score (HAZ) was also lower for underweight 2-year-olds (–0.24), making them a mean of 0.68 cm shorter than normal-weight 2-year-olds. This difference was attenuated at age 5 years.

Growth rate modified the association of underweight with both zBMI and HAZ. Among children who were underweight in the first 2 years, those with lower growth rate had lower zBMI at 10 years (–0.64) compared with those with average (–0.38) or high growth rate (0.11). Similarly, children who were underweight and had a lower growth rate at age 2 years also a lower HAZ at age 10 years (–0.12), compared with those with average (0.02) or high growth rates (0.16). These effects were more pronounced in girls.
 

Increased health risks linked with chronic underweight

This study did not assess the reasons for early underweight, Dr. Maguire commented in an interview. But, he cited challenges with dietary transitions as a possible explanation.

“Considerable dietary changes happen around 2 years of age with increasing diversity of foods as children transition from primarily liquid foods to primarily solid foods,” he noted.

Asked for comment on the study, Colleen Spees, PhD, associate professor in the division of medical dietetics and director of Hope lab at the Ohio State University, Columbus, said that “at age 10, it’s not surprising to see a lower zBMI and height-for-age in those that were underweight at age 2 with poor growth trajectories.”

Although, this is the first study she is aware of to document these findings in a Canadian cohort, “the results align with what we know about low birth weight and underweight infants and children in terms of linear growth trajectories from child stunting studies,” Dr. Spees said.

She said child stunting, which is more common in less developed countries where children have lower birth weights and greater socioeconomic and environmental risk factors, is defined by the WHO as impaired linear growth with adverse functional consequences.

“In short, a chronic underweight status in infants and young children can lead to greater risk of malnutrition, vitamin and mineral deficiencies, decreased immune function, as well as physical growth and development issues,” she said. “Hence, the most recent 2020-2025 Dietary Guidelines for Americans now includes both pregnancy, breastfeeding, and the first 2 years of life (referred to as the “first 1,000 days”) in their recommendations.”

She added that, if caregivers are concerned about their child’s weight, they should consult with their pediatrician to rule out any medical issues. If no medical issues are identified, they should ask for a referral to a pediatric dietitian.

The study was funded by the Canadian Institute of Health Research. Dr Maguire reported receiving grants from the CIHR, Physician Services, Ontario SPOR Support Unit, and Dairy Farmers of Canada during the conduct of the study and nonfinancial support from DDrops outside the submitted work. Other authors of the paper reported receiving grants from various institutions. Dr. Spees reported no relevant disclosures.

Healthy children who are underweight in the first 2 years of life continue with a lower-than-average body mass index and height-for-age through age 10, according to new research.

The association was most pronounced for girls, as well as for children with lower growth rates, write the authors of the prospective Canadian cohort study published in JAMA Network Open.

The findings “highlight the importance of preventing underweight in early life,” because this can have “lasting effects” in later childhood, senior author Jonathon L. Maguire, MD, from St Michael’s Hospital Pediatric Clinic, and the University of Toronto said in an interview.
 

Methods and results

The study recruited 5,803 healthy children, mean age 4.07 months, between February 2008 and September 2020 during well-child visits at clinics in The Applied Research Group for Kids! (TARGet Kids!) practice-based research network in Canada. The study’s exclusion criteria included a premature birth, or a health condition affecting growth.

The primary outcome of the study was the child’s age- and sex-adjusted weight, also known as the body mass index z score (zBMI), between the ages of 2 and 10 years.

At baseline, a total of 550 children (9.5%) were classified as underweight, based on the World Health Organization definition of zBMI less than –2. Underweight children were more likely to be younger, have lower birth weight, and to report Asian maternal ethnicity, the researchers observed.

The study found that, compared with children with normal weight, those who were underweight in the first 2 years had lower zBMI at ages 5 and 10 years (–0.49 and –0.39 respectively). This meant that at 10 years old, they were a mean of 1.23 kg lighter than 10-year-olds who had been normal weight at age 2 years.

Height-for-age z score (HAZ) was also lower for underweight 2-year-olds (–0.24), making them a mean of 0.68 cm shorter than normal-weight 2-year-olds. This difference was attenuated at age 5 years.

Growth rate modified the association of underweight with both zBMI and HAZ. Among children who were underweight in the first 2 years, those with lower growth rate had lower zBMI at 10 years (–0.64) compared with those with average (–0.38) or high growth rate (0.11). Similarly, children who were underweight and had a lower growth rate at age 2 years also a lower HAZ at age 10 years (–0.12), compared with those with average (0.02) or high growth rates (0.16). These effects were more pronounced in girls.
 

Increased health risks linked with chronic underweight

This study did not assess the reasons for early underweight, Dr. Maguire commented in an interview. But, he cited challenges with dietary transitions as a possible explanation.

“Considerable dietary changes happen around 2 years of age with increasing diversity of foods as children transition from primarily liquid foods to primarily solid foods,” he noted.

Asked for comment on the study, Colleen Spees, PhD, associate professor in the division of medical dietetics and director of Hope lab at the Ohio State University, Columbus, said that “at age 10, it’s not surprising to see a lower zBMI and height-for-age in those that were underweight at age 2 with poor growth trajectories.”

Although, this is the first study she is aware of to document these findings in a Canadian cohort, “the results align with what we know about low birth weight and underweight infants and children in terms of linear growth trajectories from child stunting studies,” Dr. Spees said.

She said child stunting, which is more common in less developed countries where children have lower birth weights and greater socioeconomic and environmental risk factors, is defined by the WHO as impaired linear growth with adverse functional consequences.

“In short, a chronic underweight status in infants and young children can lead to greater risk of malnutrition, vitamin and mineral deficiencies, decreased immune function, as well as physical growth and development issues,” she said. “Hence, the most recent 2020-2025 Dietary Guidelines for Americans now includes both pregnancy, breastfeeding, and the first 2 years of life (referred to as the “first 1,000 days”) in their recommendations.”

She added that, if caregivers are concerned about their child’s weight, they should consult with their pediatrician to rule out any medical issues. If no medical issues are identified, they should ask for a referral to a pediatric dietitian.

The study was funded by the Canadian Institute of Health Research. Dr Maguire reported receiving grants from the CIHR, Physician Services, Ontario SPOR Support Unit, and Dairy Farmers of Canada during the conduct of the study and nonfinancial support from DDrops outside the submitted work. Other authors of the paper reported receiving grants from various institutions. Dr. Spees reported no relevant disclosures.

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