Date Published: April 11, 2019
Publisher: Public Library of Science
Author(s): Leni Kang, Huiqing Wang, Chunhua He, Ke Wang, Lei Miao, Qi Li, Yanping Wang, Jun Zhu, Xiaohong Li, Xingzhe Liu, Jiawei Chen, Qianrun Chen, Dezhi Mu, Thach Duc Tran.
In preterm infants (i.e. the gestational age less than 37 weeks), postnatal growth remains a concern. This study used multicenter longitudinal data from China’s Under 5 Child Nutrition and Health Surveillance System to investigate the postnatal growth in the weight and length of preterm infants. Gender-stratified differences in weight and length were assessed between preterm and term infants. 1221 preterm infants and 1221 matched term infants were included. The rates of growth in weight and length in preterm infants was greater than those in term infants, especially from the first to sixth month. The rates were higher in males compared to females in the first 3 months. The differences of weight and length between preterm and term infants decreased with increasing age, however, these measurements did not reach the level of their term peers until 12 months before adjusting for gestational age. The median values of weight and length were even larger in preterm infants in the first month after adjusting for gestational age.
Preterm birth complications are the leading causes of death among children aged under 5 years globally, with an estimated 965000 deaths reported in 2013 . Additionally, these complications are the second largest contributors to the under 5 mortality in China . In addition, preterm birth has been reported to be associated with impaired neurodevelopment , adverse cognitive and behavioral outcomes , low exercise capacity , and increased risk of chronic diseases, such as hypertension , and type 2 diabetes mellitus . It has been estimated that the rate of preterm birth was 7.10% in China, amounting to approximately 1200000 preterm births in 2010 and ranking the second in the world .
A total of 2442 infants were included in the analysis, of which 1221 were born as premature. The average gestational age of preterm infants were 35.04±1.43 weeks (range: 27–36 weeks), and most of the preterm infants (76.09%) were born at greater than 34 gestational weeks. A larger proportion of preterm infants were evaluated as small for gestational age (SGA) compared to term infants (10.07% vs. 7.94%). The average maternal age at delivery was greater in the mothers of preterm infants than the mothers of term infants (29.12±5.06 vs. 27.94±4.40, p<0.001). A higher proportion of preterm infants were exclusive breastfed compared to term infants (5.03% vs. 2.72%). No differences were observed in maternal education level and migrant status between the two groups. (Table 1). In this study, we compared postnatal growth in weight and length during the first year between preterm and term infants. The preterm birth rate identified in this study was 3.53%, which is less than global estimates  but comparable with those reported in another study conducted in China (3.72%) . This study was based on community/village source (a convenience sample), and preterm infants (especially those extremely preterm infants) were less likely to be included in the routine physical examinations. Preterm infants grew faster than term infants from the first to sixth month after birth. The differences in weight and length between preterm and term infants decreased with increasing age. However, preterm infants did not reach the median values of weight and length for term infants during the first year when using the chronological age. Source: http://doi.org/10.1371/journal.pone.0213762