The effects of short- and long-duration Kangaroo Mother Care and conventional care on improving weight gain in low birth weight infants: a systematic review and meta-analysis

Abstract

Background

Kangaroo Mother Care (KMC) is a cornerstone intervention in neonatal care, widely recognized for its capacity to reduce morbidity and mortality in vulnerable newborns. Its simplicity, low cost, and adaptability make it especially valuable in resource-limited settings, where conventional neonatal intensive care may not be feasible.

Aim

This study aimed to compare the effects of long-duration KMC (≥ 8 h/day) and short-duration KMC (< 8 h/day) versus conventional care (i.e., routine incubator-based or standard neonatal care without structured skin-to-skin contact and breastfeeding support) on growth and breastfeeding outcomes in low-birth-weight (LBW) infants.

Methods

A systematic review was conducted, analyzing 10 randomized controlled trials involving 1,153 neonates, with data sourced from PubMed, Web of Science, Scopus, and EMBASE, covering studies published up to April 1, 2025.

Results

A total of 1,286 publications were initially identified, of which 10 randomized controlled trials (involving 1,153 neonates) met the inclusion criteria. For weight gain, both KMC durations improved daily gain (pooled MD = 4.52 g/day, 95% CI: 1.90–7.14), with long-duration KMC showing a greater effect (MD = 5.04 g/day, 95% CI: 0.98–9.10) compared to short-duration (MD = 3.71 g/day, 95% CI: 1.55–5.87). In length gain, the weekly increase was similar for both durations (MD = 0.09 cm/week, 95% CI: 0.06–0.12). For head circumference, short-duration KMC had a greater effect (MD = 0.07 cm/week, 95% CI: 0.04–0.10) than long-duration (MD = 0.04 cm/week, 95% CI: 0.01–0.07). Exclusive breastfeeding rates were higher with short-duration KMC (OR = 2.42, 95% CI: 1.45–4.02) compared to long-duration (OR = 1.81, 95% CI: 1.11–2.98).

Conclusion

This study demonstrates that both short- and long-duration KMC effectively improve growth and breastfeeding outcomes in LBW infants, albeit with differential advantages across endpoints. Short-duration KMC was more effective for optimizing length gain and exclusive breastfeeding, while long-duration KMC provided greater benefits for weight and head growth. The findings suggest that KMC duration should be tailored based on specific clinical needs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-025-06267-3.

Summary statement

1. What is already known about this topic?

   • Kangaroo Mother Care (KMC) is a well-established intervention for improving outcomes in low birth weight (LBW) infants.
   • Previous studies suggest that KMC enhances thermoregulation, bonding, and breastfeeding, but comparative effectiveness between continuous and intermittent KMC remains unclear.
2. What this paper adds?

   • Short-duration KMC (< 8 h/day) significantly improves weight gain and linear growth compared to conventional care, while long-duration KMC (≥ 8 h/day) shows a stronger (though non-significant) effect on head circumference growth.
   • Short-duration KMC also substantially increases exclusive breastfeeding rates (OR = 2.42) compared to conventional care.
3. The implications of this paper?

   • Healthcare providers should consider short-duration KMC as a practical and effective strategy for improving weight gain and breastfeeding rates in LBW infants, while long-duration KMC may be prioritized for additional benefits such as cranial growth and potential neurodevelopmental outcomes.

Introduction

Low birth weight (LBW) refers to infants weighing under 2500 g at birth, accounts for 14.7% of all live births globally, with a higher prevalence and associated mortality and morbidity risks in low- and middle-income countries (LMICs) [1]. Globally, an estimated 3.3 million newborns die annually, 41% of which happen within the first month of life, and LBW infants contribute to 60%–80% of these deaths [2]. Due to physiological immaturity, LBW infants are more susceptible to hypothermia, infections, respiratory distress, and growth retardation [3–5]. Therefore, improving the health outcomes of LBW infants, particularly in resource-limited community settings, remains a critical global public health challenge.

Kangaroo Mother Care (KMC) is a proven neonatal intervention centered on prolonged skin-to-skin contact between the infant and mother (or alternative caregiver), combined with exclusive breastfeeding and timely post-delivery discharge to improve outcomes for LBW newborns [6]. The practice entails positioning the infant vertically against the caregiver’s bare chest, stabilized with a supportive wrap, to optimize thermoregulation and strengthen attachment [7]. Endorsed by the WHO, KMC is recognized as a key strategy for stabilizing LBW infants, with particular emphasis on its adaptability to resource-limited and community-based settings [8, 9]. Studies have demonstrated that KMC significantly reduces neonatal mortality, infection rates, and hypothermia while improving breastfeeding rates and maternal-infant attachment [10, 11].

Although the overall benefits of KMC are well-established, the optimal implementation strategy remains debated. Some studies suggest that prolonged KMC duration enhances neonatal outcomes [12], but comparative evidence on different KMC durations is limited. In this study, we introduced a novel time-based classification, defining short-duration KMC as < 8 h/day and long-duration KMC as ≥ 8 h/day. The 8-hour cutoff was chosen to provide a reproducible, standardized threshold that aligns with literature suggesting that ≥ 6 h/day of KMC is associated with reductions in neonatal mortality, while also capturing protocols that extend beyond this threshold for potentially greater benefits [13]. This classification aims to reduce inconsistencies in prior studies that variably defined “intermittent” and “continuous” care, thereby providing a more objective framework for evaluating comparative effectiveness. We then evaluated these two modes through direct meta-analysis and network meta-analysis (NMA).

Methods

Study design

This systematic review and meta-analysis synthesizes prospective randomized controlled trials (RCTs) evaluating the health effects of KMC on LBW infants. The study adheres to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Data sources and search strategy

Electronic databases, including PubMed, Web of Science, Scopus, and EMBASE, were systematically searched for studies investigating community-based KMC interventions for LBW infants. The search strategy incorporated keywords such as “kangaroo mother care,” “skin-to-skin contact,” “low birth weight,” and “preterm,” combined with MeSH terms and free-text terms. Boolean operators (AND, OR) were used to link concepts, and truncations/wildcards were applied to broaden retrieval where appropriate. The search was conducted up to April 1, 2025, with no language or date restrictions. For non-English publications, online translation tools were used to extract English abstracts or full texts. Although the search strategy followed best-practice principles, it was not formally peer-reviewed using the PRESS checklist; however, its comprehensiveness was verified through internal team review. An example PubMed search string was:

(“Kangaroo Care” OR “Kangaroo Mother Care” OR “Skin-to-Skin Care”) AND (“Low Birth Weight” OR “Preterm Infants”) AND (“Randomized Controlled Trial” OR “RCT”). The full electronic search strategies for each database are provided in Supplementary Table S1 for transparency.”

Study selection

The PICOS (Population, Intervention, Comparison, Outcomes, Study Design) framework was applied for inclusion criteria, See Supplementary Table S2:

• Population (P): LBW infants (< 2500 g).

• Intervention (I): KMC, including continuous skin-to-skin contact, exclusive breastfeeding, and support from community health workers.

• Comparison (C): Conventional care or no KMC intervention.

Outcomes (O): Infant growth and nutritional indicators: mean daily weight gain (g/day), increase in length (cm/week), head circumference growth rate (cm/week), attainment of birth weight, and time to regain birth weight. Feeding outcomes: exclusive breastfeeding rates at discharge and at follow-up points (e.g., 1 month, 3 months), duration of exclusive breastfeeding, initiation time of breastfeeding after birth. Health outcomes: incidence of hypothermia, incidence of infection/sepsis, hospital readmission rates, and mortality during the neonatal period.

• Study Design (S): RCTs.

Studies were excluded if KMC was not explicitly defined, lacked community-based implementation, or had incomplete or inaccessible data. Two reviewers independently screened titles and abstracts for eligibility. Discrepancies at either the title/abstract or full-text stage were resolved through discussion; if consensus was not reached, a third senior investigator acted as an adjudicator.

Data extraction and quality appraisal

To ensure rigorous study selection, two researchers independently evaluated titles and abstracts before conducting full-text assessments of potentially relevant articles. A standardized data extraction template was developed in Excel to systematically record key details such as lead author, year of publication, participant characteristics, sample size, intervention protocols, follow-up period, measured outcomes, and quality appraisal criteria. Any disagreements between reviewers were resolved through consensus or by involving a senior investigator.

Methodological rigor was evaluated using the Cochrane RoB 2 tool, which examines potential biases across multiple domains, including:

• Randomization procedures.

• Allocation concealment.

• Blinding of participants and assessors.

• Handling of missing outcome data.

• Risk of selective reporting.

• Other sources of bias.

Data analysis

The analysis comprised two components: direct meta-analysis and NMA. Direct meta-analysis was performed using R software. For continuous variables, mean differences (MD) with 95% confidence intervals (CI) were calculated; for dichotomous variables, odds ratios (OR) with 95% CI were used. Heterogeneity was assessed via χ² tests and I² statistics. A fixed-effects model was applied if P ≥ 0.1 and I² ≤ 50%, indicating low heterogeneity; otherwise, a random-effects model was used. Publication bias was evaluated using funnel plots and Egger’s test. Asymmetrical funnel plots or Egger’s test results (P < 0.05) suggested potential bias, prompting sensitivity analyses.

Network meta-analysis was conducted using STATA’s network package. A network plot was generated to visualize intervention comparisons. Both direct and indirect evidence were integrated under the assumption of consistency and transitivity. Node-splitting analysis tested consistency between direct and indirect evidence; if inconsistency was detected (P < 0.05), an inconsistency model was applied. Bayesian frameworks estimated pooled effect sizes (OR/MD with 95% CI). Surface Under the Cumulative Ranking Curve (SUCRA) probabilities ranked intervention efficacy.

Results

Literature screening process

A systematic search of databases including Web of Science, PubMed, Scopus, and EMBASE initially yielded 1,286 relevant articles (search cutoff date: April 1, 2025). After removing duplicates using EndNote software, 492 articles remained. Two independent reviewers then conducted preliminary screening based on titles and abstracts, excluding studies that clearly did not meet the inclusion criteria (e.g., non-randomized controlled trials, studies not involving low birth weight infants, interventions not involving KMC or conventional care). At this stage, 375 articles were excluded, leaving 117 for full-text review.

Full-text retrieval and detailed evaluation were performed for 117 articles, with exclusions as follows: 45 due to unclear intervention descriptions (e.g., lack of distinction between continuous or intermittent KMC modes); 32 due to unavailable data (e.g., unreported outcomes such as weight, length, head circumference, or breastfeeding rates, or data that could not be extracted); 18 due to non-conforming study designs; and 12 due to overlapping data (e.g., duplicate publications of the same trial, multiple reports from the same cohort, or studies where outcome data had already been included in another eligible publication). At each screening stage, disagreements between the two reviewers were resolved through discussion; if consensus could not be reached, a senior investigator acted as an adjudicator. Ultimately, 10 randomized controlled trials met the inclusion criteria. For the purposes of this review, interventions were further classified based on daily KMC duration:

• Short-duration KMC: <8 h/day (5 studies)

• Long-duration KMC: ≥8 h/day (5 studies)

All studies compared KMC with conventional care, with no direct comparisons between short- and long-duration KMC. The selection process is summarized in Fig. 1.

Fig. 1.

PRISMA Flowchart of Literature Screening

Basic characteristics of included studies

A total of 10 studies were included, categorized by KMC duration into continuous KMC (3 studies) and intermittent KMC (7 studies). All studies compared KMC with conventional care, with no direct comparisons between continuous and intermittent KMC. The total sample size was 1,153 infants (intervention group: 586; control group: 567) (Table 1). The Risk of Bias (ROB) assessment indicated moderate or low study quality due to the inability to blind participants and researchers given the nature of the intervention. The ROB assessment is summarized in Fig. 2.

Table 1.

Basic characteristics of included studies

Study	Birthweight	Reported KMC duration	Authors’ grouping	n.KMC	n.Con	Daily duration category	Notes
Acharya N 2014 [14]	< 2000 g	≥ 6 h/day	Intermittent	63	63	Long	Explicitly defined in methods.
Boo NY 2007 [15]	< 1501 g	≥ 1 h/day (possible up to 12 h)	Intermittent	64	62	Short–Long (ambiguous)	Wide range possible; no upper bound fixed.
Cattaneo 1998 [16]	< 2000 g	“Day and night”	Continuous	146	133	Long	Implies near-continuous.
Yin T 2017 [17]	1000–1499 g	2 h/day	Intermittent	80	80	Short	Clearly short duration.
Gathwala G 2010 [18]	< 1800 g	≥ 6 h/day	Intermittent	50	50	Short–Long (borderline)	Threshold close to cut-off.
Ghavane S 2012 [19]	< 1500 g	“As many hours/day as possible”	Continuous	68	68	Long	Encouraged maximum hours.
Rojas MA 2003 [20]	< 1500 g	8 h/day	Intermittent	30	26	Long	Meets ≥ 8 h/day criterion.
Lumbanraja 2016 [21]	< 2500 g	4–6 h/day	Intermittent	20	20	Short	Below 8 h/day threshold.
Hoque M 2017 [22]	1250–1800 g	10–12 h/day	Intermittent	40	40	Long	Above threshold.
Ahmed M 2019 [23]	1250–1800 g	≥ 12 h/day	Continuous	25	25	Long	Above threshold but < 20 h/day.

Fig. 2.

Risk of bias assessment for included randomized controlled trials using the Cochrane RoB 2 tool. Domains assessed include: bias arising from the randomization process, deviations from intended interventions, missing outcome data, measurement of the outcome, and selection of the reported result. Most studies were rated as having moderate or low overall risk of bias, with the primary limitation being the inability to blind participants and caregivers inherent to the nature of Kangaroo Mother Care (KMC) interventions

Direct meta-analysis results (short- vs. long-duration KMC)

Neonatal daily weight gain

Ten randomized trials reported daily weight gain; five were classified as short-duration KMC (< 8 h/day) and five as long-duration KMC (≥ 8 h/day). Due to substantial heterogeneity, we used a random-effects model. The pooled MD for all KMC versus control was 4.52 g/day (95% CI: 1.90, 7.14). In subgroup analyses, short-duration KMC showed 3.71 g/day (95% CI: 1.55, 5.87), and long-duration KMC 5.04 g/day (95% CI: 0.98, 9.10) (Fig. 3).

Fig. 3.

Short vs. long duration KMC, with subgroup and overall effects

Neonatal weekly length gain

Six trials reported weekly length gain. The pooled MD for all KMC versus control was 0.09 cm/week (95% CI: 0.06, 0.12); short-duration KMC 0.09 cm/week (95% CI: 0.04, 0.14), long-duration KMC 0.09 cm/week (95% CI: 0.05, 0.12) (random-effects) (Fig. 4).

Fig. 4.

Weekly length gain, short vs. long duration KMC

Neonatal weekly head circumference gain

Seven trials reported weekly head circumference gain. The pooled MD for all KMC versus control was 0.05 cm/week (95% CI: 0.03, 0.07); short-duration KMC 0.07 cm/week (95% CI: 0.04, 0.10), long-duration KMC 0.04 cm/week (95% CI: 0.01, 0.07) (Fig. 5).

Fig. 5.

Weekly head circumference gain, short vs. long duration KMC

Exclusive breastfeeding rate

Six trials reported EBF at discharge or at the prespecified follow-up point. The pooled OR for all KMC versus control was 2.09 (95% CI: 1.46, 2.97); short-duration KMC 2.42 (95% CI: 1.45, 4.02), long-duration KMC 1.81 (95% CI: 1.11, 2.98) (random-effects). (Fig. 6)

Fig. 6.

Exclusive breastfeeding rate, short vs. long duration KMC

Publication bias and sensitivity analysis

Publication bias was assessed using Egger’s test and funnel plots. While Egger’s test did not indicate significant bias for any outcome, its reliability was limited due to the small number of included studies. Funnel plots exhibited asymmetry, suggesting potential publication bias (Fig. 7).

Fig. 7.

Funnel Plots for Publication Bias Assessment. Note: A Daily weight gain; B Weekly length gain; C Weekly head circumference gain; D Exclusive breastfeeding rate

Sensitivity analysis was conducted by sequentially excluding individual studies. For daily weight gain, the MD ranged from 2.62 to 4.15; for weekly length gain, from 0.14 to 0.20; for weekly head circumference gain, from 0.06 to 0.15; and for exclusive breastfeeding rates, the OR ranged from 1.72 to 2.45. Sensitivity analysis results are presented in Fig. 8.

Fig. 8.

Sensitivity Analysis Forest Plots. Note: A Daily weight gain (mean difference, g/day); B Weekly length gain (mean difference, cm/week); C Weekly head circumference gain (mean difference, cm/week); D Exclusive breastfeeding rate (odds ratio). Each plot shows effect estimates for Kangaroo Mother Care (KMC, intervention) versus conventional care (control). Left of the vertical line favors KMC; right favors conventional care.

Network meta-analysis

To further compare the effects of the three interventions (intermittent KMC, continuous KMC, and conventional care) on weight, length, head circumference, and exclusive breastfeeding rates, a network meta-analysis was performed based on direct meta-analysis results. No studies directly compared intermittent and continuous KMC for any outcome. The network plots for the four outcomes are shown in Fig. 9.

Fig. 9.

Network Plots for Network Meta-Analysis Note: A Daily weight gain; B Weekly length gain; C Weekly head circumference gain; D Exclusive breastfeeding rate

Inconsistency models were applied where significant inconsistency was detected; otherwise, consistency models were used. SUCRA was employed to rank the three interventions. For daily weight gain, SUCRA rankings were: continuous KMC (0.913), intermittent KMC (0.579), and control (0.008). For weekly length gain: intermittent KMC (0.872), continuous KMC (0.455), and control (0.173). For weekly head circumference gain: intermittent KMC (0.759), continuous KMC (0.500), and control (0.241). For exclusive breastfeeding rates: intermittent KMC (0.987), continuous KMC (0.433), and control (0.800). The SUCRA rankings are illustrated in Fig. 10.

Fig. 10.

SUCRA Rankings for Network Meta-Analysis. Note: A Daily weight gain; B Weekly length gain; C Weekly head circumference gain; D Exclusive breastfeeding rate

Discussion

This systematic review and meta-analysis synthesized evidence from randomized controlled trials comparing short-duration (< 8 h/day) and long-duration (≥ 8 h/day) KMC with conventional care in LBW infants. Across all pooled analyses, KMC significantly improved neonatal growth outcomes and exclusive breastfeeding rates, regardless of daily duration. Daily weight gain increased by an average of 4.52 g/day overall, with both short-duration (3.71 g/day) and long-duration (5.04 g/day) KMC showing benefit compared to control. Weekly length gain improved similarly in both subgroups (0.09 cm/week), while weekly head circumference gain was greater in the short-duration group (0.07 cm/week) than in the long-duration group (0.04 cm/week). Exclusive breastfeeding rates increased by 2.09-fold overall, with a stronger association in short-duration KMC (OR 2.42) than in long-duration KMC (OR 1.81). These results suggest that meaningful growth and feeding improvements can be achieved with as little as several hours of daily KMC.

The core mechanisms underlying these benefits remain consistent with prior literature—thermoregulation, reduced energy expenditure, and enhanced maternal-infant bonding redirect metabolic resources toward growth [8]. Shorter, repeated KMC sessions may minimize fatigue and optimize feeding frequency, which could explain why short-duration KMC performed comparably or better in some outcomes despite lower daily exposure. This hypothesis is supported by Mazumder et al., whose community-based randomized trial showed that intermittent KMC (≥ 8 h/day) significantly reduces infant mortality and improves growth outcomes [11]. The association between head circumference growth and continuous KMC may reflect long-term neurodevelopmental benefits. Prolonged skin-to-skin contact and maternal interaction in continuous KMC could stimulate vagal nerve activity and growth hormone secretion, influencing cranial development. Similarly, Zhang et al. [24] reported that head circumference growth in preterm infants correlates with neurodevelopmental outcomes, and sustained care interventions optimize brain volume development. However, the robustness of this finding is limited by the small number of studies on continuous KMC (n = 1).

The enhancement of exclusive breastfeeding rates is another notable advantage of KMC. Joshi et al. [7] proposed that KMC strengthens maternal-infant bonding and tactile stimulation, directly promoting prolactin and oxytocin release to increase milk production.

Our reclassification of KMC into short (< 8 h/day) and long (≥ 8 h/day) daily durations addresses a major methodological gap in prior reviews that compared “intermittent” and “continuous” KMC. These earlier definitions were inconsistent, with some “intermittent” protocols lasting over 12 h/day, overlapping with what other studies termed “continuous.” By adopting a reproducible, time-based cut-off, we reduced misclassification bias and included trials with ambiguous terminology, thereby providing a more objective framework for comparison and clinical recommendations. Beyond daily duration, the timing of KMC initiation may also influence outcomes. For example, Arya et al.’s multicenter trial [9] demonstrated that immediate initiation after birth significantly improved exclusive breastfeeding rates (78% vs. 52% with conventional care). Thus, our classification not only clarifies previous inconsistencies but also complements existing reviews by offering a practical, standardized approach to evaluating KMC effectiveness.

In resource-limited settings, KMC is a low-cost, scalable intervention with substantial public health value. This study found that even intermittent KMC (a few hours daily) significantly improves growth outcomes, offering a feasible solution for families unable to provide 24-hour continuous care. For instance, in sub-Saharan Africa, Mazumder et al.’s [11] community trial demonstrated that training community health workers to promote KMC increased 6-month survival rates of LBW infants to 89% (vs. 76% in controls). Moreover, KMC’s breastfeeding benefits reduce reliance on formula, mitigating infection and malnutrition risks—particularly crucial in under-resourced regions [25]. However, mode selection should be context-specific: intermittent KMC may suit hospital settings or high-risk infants, whereas continuous KMC could be more effective in community or home-based care. Studies suggest that ≥ 6 h/day of maternal KMC achieves outcomes comparable to hospital-based continuous care, with higher family engagement [26]. Mode selection for KMC should be context-specific, taking into account factors such as the setting (hospital vs. community/home-based), the health status of the infant, and available resources [27]. In hospital settings, where neonates may be at higher risk or require more intensive monitoring, intermittent KMC (e.g., 3–4 h a day) can offer a balance between the benefits of skin-to-skin contact and medical interventions [28]. This form of care might also be more practical in settings where resources such as trained personnel or space are limited [29]. On the other hand, continuous KMC is often more beneficial for term or stable low-birth-weight infants, particularly in community-based or home settings, where caregivers can provide extended skin-to-skin contact without the constraints of hospital infrastructure [30].

Studies consistently suggest that ≥ 6 h of daily maternal KMC can achieve outcomes comparable to those seen in hospital-based continuous KMC [31, 32]. Importantly, this level of care not only improves neonatal outcomes such as weight gain, temperature regulation, and reduced mortality, but also fosters a higher level of family engagement [33]. This engagement is crucial, as it empowers mothers and other caregivers, encourages bonding, and facilitates the development of a nurturing caregiving environment, all of which play a key role in the infant’s emotional and physiological development [34]. The flexibility of KMC models allows it to be adapted to various contexts, thereby ensuring that more families can benefit from this life-saving intervention [35]. Yet, Sivanandan et al.’s meta-analysis indicated that ≥ 8 h/day is required for significant mortality reduction [13]. Thus, future clinical guidelines should refine KMC protocols, tailoring recommendations to resource availability and family circumstances.

The enhancement in exclusive breastfeeding rates aligns with established evidence that skin-to-skin contact stimulates oxytocin and prolactin release, increasing milk production and facilitating early initiation [13, 34]. Our finding that short-duration KMC achieved a higher odds ratio for breastfeeding success may be related to its flexibility, allowing mothers to integrate KMC into daily routines more sustainably. In contrast, long-duration KMC, while beneficial, may be harder to maintain in hospital or working contexts.

From a public health perspective, the observation that both short and long KMC durations improve growth and feeding outcomes is critical for resource-limited settings. Even partial daily implementation may be sufficient to achieve clinically relevant benefits where continuous care is impractical. Evidence from community trials shows that integrating KMC promotion into maternal and child health programs can substantially improve survival, feeding, and growth outcomes without heavy infrastructure investment [11]. However, heterogeneity across studies was substantial. This variability likely stems from differences in baseline infant health, gestational age, maternal nutritional status, KMC initiation timing, and hospital vs. community settings. Such heterogeneity may also have contributed to the asymmetry observed in some funnel plots, alongside potential small-study effects. Although Egger’s test did not indicate statistically significant publication bias, the limited number of studies per outcome reduces confidence in this finding.

Strengths and limitations

A key strength of this review is the standardized time-based classification of KMC duration, enabling a clearer evaluation of dose-response effects. The inclusion of exclusively randomized trials strengthens causal inference. Limitations include possible residual confounding from unmeasured factors such as feeding supplementation, lack of data on adherence, and the relatively small number of trials in each subgroup, particularly for long-duration KMC in some outcomes.

Implications for practice and research

Given that both short- and long-duration KMC confer measurable benefits, clinical guidelines should emphasize feasibility and sustainability rather than adherence to rigid daily hour thresholds. Future trials should adopt standardized KMC duration reporting and explore threshold effects for specific outcomes. Additionally, more granular measurement of feeding practices and neurodevelopmental outcomes would help clarify whether certain durations preferentially benefit different domains of infant health.

Conclusion

This study demonstrates that both short- and long-duration KMC effectively improve growth and breastfeeding outcomes in LBW infants, albeit with differential advantages across endpoints. These findings endorse KMC as a core strategy for LBW care while emphasizing the need for context-adapted implementation. Future high-quality studies should further validate the benefits of long-duration KMC and standardize its global application.

Authors’ contributions

Z.G. and J.H. conceived the study. L.Z. designed the research. Z.G. and L.Z.collected the data and performed the statistical analysis.Z.G. and L.Z. wrote the manuscript and G.Z.and J.H.revised the manuscript. All authors contributed to the drafting of the manuscript and approved the final version of the manuscript. L.Z. shall act as the corresponding author of the paper.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

Data availability

The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.