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Updated: Jul 14, 2025
Assessment of Child Anthropometry in a Large Epidemiologic Study
Published on: February 2, 2017
A retrospective study on the physical growth of twins in the first year after birth
Ting Pan1, Yanru Huang1,2, Qian Cheng1
1Department of Child Health Care, Chongqing Growth, Development and Mental Health Center for Children and Adolescents, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Child Health and Nutrition, Children's Hospital of Chongqing Medical University, Chongqing, China.
Insights
Twin growth in the first year reaches normal ranges but not singleton averages. Small for gestational age (SGA) twins, especially preterm, require closer monitoring and nutritional guidance for optimal weight for length.
Area of Science:
- Pediatrics
- Neonatology
- Twin Studies
Background:
- Small for gestational age (SGA) and appropriate for gestational age (AGA) twins exhibit distinct growth patterns.
- Understanding twin growth trajectories is crucial for identifying potential developmental issues.
Purpose of the Study:
- To analyze and compare the physical growth of SGA and AGA twins up to one year of age.
- To evaluate key growth parameters including weight, length, head circumference, and body proportion.
Main Methods:
- Retrospective analysis of 3,909 twin cases from 2010-2019.
- Data collected on weight, length, and head circumference, presented as Z-scores.
- Comparison of five growth parameters: weight, length, head circumference, growth velocity, and weight-for-length proportion.
Main Results:
- Both SGA and AGA twins' Z-scores (Weight-for-age, Head circumference-for-age, Length-for-age) improved in the first six months, reaching normal ranges by one year but not singleton averages.
- AGA twins' mean Z-scores were between -1 and 0, while SGA twins were between -2 and -1, indicating significant lag in SGA.
- Preterm AGA twins showed the highest growth rate and potential, but preterm SGA twins consistently exhibited low growth.
- Weight-for-length Z-scores remained near 0, with SGA twins showing lower values than AGA twins, and a downward trend after four months.
Conclusions:
- Twin growth in the first year can normalize but does not reach singleton averages.
- SGA twins, particularly preterm infants, warrant increased attention and targeted nutritional support after four months to optimize body proportion.
Objectives:
This study analyzed the physical growth of small for gestational age (SGA) and appropriate for gestational age (AGA) twins up to one year after birth.
Methods:
Weight, length, and head circumference data of 0-1 year-old twins were collected from the Child Health Care System from 2010 to 2019. Physical data were presented as Z-scores. Five parameters - growth level of weight, body length, head circumference, growth velocity, and body proportion (weight for length) were compared in twins.
Results:
A total of 3,909 cases were collected (22.61% SGA, 77.39% AGA). 1. In both groups, WAZ (Weight for age z-score), HCZ (Head circumference for age z-score), and LAZ (Length for age z-score) increased more rapidly in the first 6 months. By one year of age, WAZ, HCZ, and LAZ had reached the normal range, but none had reached the average level of normal singleton children. 2. The mean values of WAZ, HCZ, and LAZ in the AGA group were between -1 and 0, and between -2 and - 1 in the SGA group, in the first year after birth. The SGA group lagged significantly behind the AGA group. The LAZ score of SGA and AGA was lower than the WAZ and HCZ scores. 3. The proportion of preterm AGA was the largest in twins, and the growth rate of preterm AGA was the fastest. Preterm twins had greater growth potential than term twins. However, the growth level of preterm SGA was always low. 4. The WFLZ (Weight for length z-score) in each group was approximately close to 0. The WFLZ of SGA was smaller than that of AGA twins at most time points. After 4 months of age, the WFLZ of twins had a downward trend. The WFLZ of preterm SGA approached -1 at approximately 1 year old.
Conclusion:
The physical growth of SGA and AGA in twins in the first year can reach the normal range but cannot reach the average level of normal singleton children. More attention should be paid to SGA in twins, especially preterm SGA. We should give proper nutritional guidance after 4 months of age to ensure the appropriate body proportion (weight for length) of SGA in twins.
Clinical Trial Registration:
www.chictr.org.cn, CTR2000034761.
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