[Relationship between energy intake and catch-up growth in full-term small-for-gestational-age infants under 6 months of age]

To explore the relationship between nutrition and catch-up growth in full-term small-for-gestational-age infants under 6 months of age.

A prospective cohort study was conducted to collect clinical data of full-term small for gestational-age infants (SGA) and full-term appropriate-for-gestational-age infants (AGA) from the Department of Health Care of the Children's Hospital of Chongqing Medical University. According to inclusion criteria, between February 2014 and April 2015, the infants were divided into three groups: AGA, SGA with catch-up growth (ΔSDS of weight≥0.67), and SGA with no catch-up growth (ΔSDS <0.67). ΔSDS was the ΔZ of weight, calculated using the standard deviation of the dispersion method (Z score). Chi-square was used to compare differences in feeding patterns between the catch-up growth and no catch-up growth groups. Analysis of variance was used to compare differences between the three groups in daily energy intake and protein to energy ratios.

Totally 180 SGA infants within 6 months of age were enrolled, among whom 63 were male, 117 were female; and 48 AGA infants were enrolled, among whom 19 were male, 29 were female. There were no significant differences in the feeding patterns (breast feeding, partial breast feeding or full formula feeding) of SGA catch-up and SGA no catch-up groups at 1, 3 or 6 months during the first year (43 (75.4%) vs. 75 (61.0%), 7 (12.3%) vs. 25 (20.3%), 7 (12.3%) vs. 23 (18.7%) at 1 month, 70 (66.7%) vs. 39 (53.4%), 13 (12.4%) vs. 12 (16.4%), 22 (21.0%) vs. 22 (30.1%) at 3 months, 30 (31.6%) vs. 16 (23.5%), 14 (14.7%) vs. 12 (17.6%), 51 (53.7%) vs. 40 (58.8%) at 6 months, χ(2)=3.263, 3.207, 1.308 respectively, all P>0.05). The total daily energy intake (kJ/d) of the SGA no catch-up group was significantly lower than that of the AGA group at 1, 3 and 6 months of age (1 668±350 vs. 1 841±426, 1 889±276 vs. 2 330±379, 2 175±349 vs. 2 556±354, respectively, all P<0.05). It was also significantly lower than that of the SGA catch-up group at 3 months (1 889±276 vs. 2 118±361, P<0.05). The total daily energy intake of the SGA catch-up group was significantly lower than that of the AGA group at 3 and 6 months (2 118±361 vs. 2 330±379, 2 336±374 vs. 2 556±354, respectively, all P<0.05). The average daily energy intake (kJ/(kg·d)) of the SGA no catch-up group was significantly greater than that of the SGA catch-up and AGA groups at 1 and 6 months (483±113 vs. 413±79 vs. 407±82, 343±52 vs. 321±56 vs. 310±47, respectively, all P<0.05). However, there was no significant difference between the SGA catch-up group and AGA group (all P>0.05). The protein to energy ratio(g/100 kJ)of the SGA no catch-up group was significantly higher than that of the SGA catch-up and AGA groups at 6 months (0.59±0.09 vs.0.51±0.07 vs. 0.50±0.07, P<0.05). There was no significant difference between the SGA catch-up group and AGA group (all P>0.05). Differences in energy intake at 1, 3 and 6 months were also compared between the SGA catch-up and SGA no catch-up groups using repeated measures analysis of variance.The results suggested the total daily energy intake in the SGA catch-up group within 6 months was higher than the SGA no catch-up group (F=7.512, P<0.05), but there were no significant differences in average daily energy intake (F=0.345) or protein to energy ratio (F=0.436) between the two groups (all P>0.05).

There was no relationship between catch-up growth and feeding patterns or average daily energy intake of full-term small for gestational age infants under 6 months of age.