In this retrospective study, a total of 104 preterm infants born in our hospital between January 2023 and December 2023 were enrolled. No a priori sample size calculation was performed due to the retrospective nature of the study. All eligible infants admitted during the study period were included to minimize selection bias. Based on the nursing approach they received during their hospitalization, they were divided into the routine care group (n = 49) and the developmental supportive care group (n = 55). Group assignment was not randomized but was determined by the clinical practice and nursing schedule in effect during the infant's hospitalization period. All infants were hospitalized in the Neonatal Intensive Care Unit (NICU) throughout the study period. The care commenced within 72 h after birth and continued for 7 days during NICU hospitalization. Baseline assessments were conducted before care initiation. Post-care evaluations for growth and neurobehavioral function were performed at the end of the 7 days hospitalization period. Cognitive development was assessed at a follow-up visit when infants reached a corrected age of 40 weeks. This study was approved by the Ethics Committee of Zhangjiakou First Hospital (Approval No. 2025-LW-32). Informed consent was obtained from the guardians of all newborns included in the study.

Inclusion criteria: Preterm infants meeting the diagnostic criteria for late preterm birth, with a gestational age of 34 ≤ 37 weeks; admitted within 72 h after birth; complete clinical data available.

Exclusion criteria: Infants with gestational age >34 weeks who have severe congenital malformations, chromosomal abnormalities, or inherited metabolic disorders. Death during hospitalization, voluntary discharge, or discontinuation of treatment (Figure 1).

The routine care group received routine neonatal care during hospitalization. This included: (1) Routine monitoring: Daily assessment of vital signs, including body temperature, respiration, heart rate, and oxygen saturation; routine laboratory tests such as blood glucose and blood gas analysis were performed as prescribed. (2) Basic feeding care: Infants were fed breast milk or formula according to medical orders; tube feeding was performed when necessary. Position changes and back patting were conducted on schedule to assist with gas expulsion. (3) Environmental management: The ward environment was maintained at appropriate temperature (24℃–26℃) and humidity (50%–60%), kept quiet and clean, with strict adherence to hand hygiene and aseptic procedures. (4) Routine skin and oral care: Skin cleaning, diaper changes, and umbilical cord care were performed daily or per shift according to the nursing pathway. Oral care was provided as needed, using gauze or cotton swabs for gentle wiping. (5) Routine positioning and bedding: Positions (supine or lateral) were changed as clinically required, without specialized “nest-style” supports or positioning aids. (6) Disease management: Abnormal conditions such as apnea, pallor, or vomiting were promptly reported and managed. (7) Health education and psychological care: Parents received education on routine neonatal care to reduce anxiety.

The developmental supportive care group received developmental supportive care in addition to routine neonatal care during hospitalization. The developmental supportive care was implemented by a multidisciplinary team including NICU nurses, neonatologists, physical therapists, and nutritionists. Regular team meetings were conducted to ensure consistent application of DSC principles and coordinate care activities. The NICU nurses responsible for delivering DSC had received specialized, advanced training in developmental care principles. This training comprised a structured 20-h program covering the theoretical foundations of developmental supportive care, practical care techniques (such as positioning, tactile stimulation, and pain management), and competency-based assessment. Furthermore, all these nurses held a bachelor's degree or higher in nursing and had a minimum of two years of NICU experience.

The care period lasted 7 days. Specific measures are summarized in Table 1.

Parental involvement was actively encouraged and structured. Parents received comprehensive education on DSC principles and techniques, including hands-on training in kangaroo care, feeding optimization, and behavioral observation. They were guided to participate in daily care activities and record infant responses under nursing supervision.

The observation indicators included:

Growth parameters: Changes in body weight, length, head circumference, and chest circumference after the care were recorded and compared with pre-care values and the routine care group to evaluate the effect of the care on the growth and development of preterm infants.

Statistical analyses were performed using SPSS version 27.0. Continuous variables were tested for normality using Shapiro–Wilk test and are presented as mean ± standard deviation. Categorical data are presented as frequencies and percentages (n/%). Between-group comparisons of baseline characteristics and outcome measures were analyzed using independent t-tests for continuous variables and χ² tests for categorical variables. Within-group changes from baseline to post-intervention were analyzed using paired t-tests. A p-value of <0.05 was considered statistically significant.

The baseline demographic and clinical characteristics of the preterm infants in both groups are presented in Table 2. There were no statistically significant differences between the routine and developmental supportive care groups in terms of gender, mode of delivery, Apgar score, or incidence of complications (all P > 0.05), indicating that the two groups were comparable before the care. Most importantly, there was no significant difference in gestational age between the two groups (P = 0.941). This baseline comparability in the most critical determinant of newborn growth and development strengthens the validity of directly comparing post-care outcomes between the groups (Table 2).

Developmental supportive care significantly enhanced growth parameters in preterm infants compared to routine care. After the 7 days care period, all growth parameters increased in both groups (all P < 0.05). Moreover, the developmental supportive care group demonstrated substantially greater improvements in body weight (2.28 ± 0.25 kg vs. 2.12 ± 0.40 kg, P = 0.011), length (46.76 ± 2.76 cm vs. 44.59 ± 2.66 cm, P < 0.001), head circumference (32.61 ± 1.68 cm vs. 31.52 ± 1.65 cm, P = 0.001), and chest circumference (33.71 ± 2.91 cm vs. 31.58 ± 3.14 cm, P < 0.001) (Table 3).

Developmental supportive care group showed significantly greater improvements in neurobehavioral outcomes across all measured domains. After the care, all these neurodevelopmental indicators improved in both groups (all P < 0.05). Moreover, developmental supportive care resulted in superior scores in passive muscle tone (5.80 ± 1.20 vs. 4.50 ± 0.86, P < 0.001), behavioral state (8.58 ± 1.21 vs. 6.99 ± 1.26, P < 0.001), primitive reflexes (5.26 ± 0.68 vs. 4.26 ± 0.99, P < 0.001), active muscle tone (6.21 ± 1.03 vs. 5.03 ± 1.00, P < 0.001), and general condition (5.04 ± 0.90 vs. 4.20 ± 0.83, P < 0.001) compared to the routine care group (Table 4).

Developmental supportive care significantly enhanced cognitive and psychomotor development in preterm infants. After the care, both MDI and PDI scores increased in both groups (all P < 0.05). Moreover, the developmental supportive care group achieved markedly higher MDI scores (90.89 ± 5.33 vs. 81.30 ± 4.89, P < 0.001) and PDI scores (91.98 ± 6.18 vs. 87.13 ± 5.92, P < 0.001) following the intervention period compared to the routine care group (P < 0.05) (Table 5).