This study is the largest and one of only a few studies on KMC and breastfeeding in China. Our analysis shows that KMC was associated with a nearly two-fold increase in exclusive breast milk feeding (outcome) and breastfeeding (method) at both discharge and follow up in late preterm infants. Our results suggest that for late preterm infants, cared for on postnatal wards with their mothers, relatively brief exposure to intermittent KMC in hospital was associated with increased exclusive breastfeeding at discharge and at follow up.
Breastfeeding is routinely promoted to mothers during pregnancy and during their hospital stay in all participating hospitals in this study. This includes breastfeeding knowledge; the definition of exclusive breastfeeding, benefits of exclusive breastfeeding for 6 months, and positions for breastfeeding. The definition of exclusive breastfeeding is in accordance with the WHO’s definition where no other food or drink, not even water, except breast milk is allowed . Nurses will observe mothers breastfeeding their baby daily during hospital stay and provide advice as needed. Despite this ongoing effort, the exclusive breastfeeding rate in China remains low (29.2% at 6 months) . Our results suggest that intermittent KMC may help combat the low breastfeeding rates for preterm infants.
There is a greater likelihood that preterm infants will commence breastfeeding later and cease breastfeeding earlier than infants born at term , due to a series of barriers including but not limited to a lack of or perceived lack of adequate breast milk, an infant’s immature uncoordinated sucking and swallowing mechanism and an increased likelihood of maternal symptoms of depression due to preterm delivery [6,13,14]. This also applies to late preterm infants [15,16]. Inadequate milk intake contributes to slow weight gain and protracted jaundice in late preterm infants, making routine formula supplementation and early termination of breastfeeding more likely .
Our study results are consistent with previous evidence from published literature that frequent skin-to-skin contact between mother and infant is crucial to the successful transition to direct breastfeeding in preterm infants [9,14] and initiation of exclusive breastfeeding in healthy full-term infants . Early skin-to-skin contact, within the first hour of birth, if possible, facilitates maternal milk production [19,20]. While continued skin-to-skin contact on a daily basis accelerates neurophysiological development of the preterm infant , which contributes to establishment of an effective suckling mechanism. KMC on postnatal wards minimizes maternal-infant separation time and promotes increased breastfeeding [6,22].
It is noteworthy that KMC may play a role in alleviating stress related to preterm birth, encouraging mothers to care for their late preterm infants and breastfeed. Parents of late preterm infants are likely to exhibit a lack of confidence and some may exhibit distress during feeding or symptoms of depression [23–25]. A previous study on breastfeeding outcomes for preterm infants in China suggests that mothers of preterm infants perceived their ability to breastfeed to be low and were more likely to have symptoms of depression, contributing to the unsuccessful establishment of breastfeeding . It is likely that KMC encourages mothers, helps relieve stress and boosts their confidence, this in addition to the breastfeeding support provided by nurses and health professionals could positively contribute to the successful initiation of breastfeeding in late preterm infants.
Our analyses indicate that intermittent KMC on postnatal wards, even for a relatively short duration, may have an impact on exclusive breastfeeding, not only at discharge, but up to 42 days after discharge. Given the extremely low exclusive breastfeeding rate (29.2%) at 6 months of age in China , our study has strong public health implications. KMC is recommended for infants under 2000g, however use of intermittent KMC for late preterm infants on postnatal wards could be encouraged by health professionals in order to improve breastfeeding outcomes.
There is limited research regarding KMC in late preterm infants breastfeeding especially infants who are not low birth weight. According to our literature search, previous studies either did not report the characteristics of KMC (continuous vs. intermittent)  or did not analyze breastfeeding patterns . We have identified two studies with similarities to ours. Nyqvist (2008) reported the association between KMC duration with breastfeeding rate in 128 healthy late preterm (average weight 2.9kg)-parent infant pairs in Sweden, however a significant association was only found for fathers providing KMC and not mothers . A randomized controlled trial conducted by Hake-Brooks and Anderson in the US in 2008 included 66 preterm infants born at different gestations (47% were of 36 weeks gestational age) and reported a nearly doubled increase in the exclusive breastfeeding rate (72% vs. 60% at discharge, 33% vs. 17% at 6 weeks, 19% vs 3% at 3 months, 8% vs. 0% at 6 months) though they did not disaggregate their analysis by gestational age and half of the infants were cared for on neonatal intensive care units . To reach a firm conclusion regarding the effect of intermittent KMC on breastfeeding in heavier late preterm infants, further studies are needed.
Our study adds value to the global literature on KMC. Firstly the study population, late-preterm infants, is a population understudied and often overlooked in KMC literature. Secondly our study suggests that a relatively brief period of intermittent KMC is associated with significant increases in exclusive breastfeeding rates. If our findings were corroborated by more rigorous research design for example quasi-experimental study in the future, a strong recommendation for intermittent KMC for late preterm infants in similar settings could be made as a low cost and feasible solution to increasing breastfeeding rates. Lastly, considering the extremely low exclusive breastfeeding rate in China, KMC promotion for late preterm infants on postnatal wards may be an effective and feasible strategy to increase breastfeeding rates in China, which could have huge public health impact including but not limited to improved newborn health outcomes.
We recognize that our study has several limitations. Firstly it is not a randomized controlled trial., as KMC is known to be beneficial for preterm infants it was deemed unethical to randomize mothers and infants to a group where they would not be encouraged to practice KMC. It is also possible that those who opted to provide KMC may have been more likely to breastfeed their infants than those who chose not to provide KMC; however, we found no significant difference in socio-demographic characteristics (including age and educational attainment) between the two groups. Moreover, the exclusive breastfeeding rate for mothers who did not provide KMC (33.2% at 42 days follow-up) is similar to the national exclusive breastfeeding rate at 6 months of age (29.2%); therefore, we believe our finding that KMC was associated with an increase in breastfeeding rates is valid. Nonetheless, this is a cross-sectional study and part of a larger piece of implementation research on the introduction of KMC to China’s postnatal and neonatal wards, as such the primary aim of the overarching study was not to access the effectiveness of KMC to improve breastfeeding rates but to investigate the feasibility of intermittent KMC on postnatal and neonatal wards and understand the resulting use of KMC by mothers, thus the interpretation of the results should be made with caution without implying any causal inference.
Secondly we noted a difference in the KMC vs. No KMC ratio across the four participating hospitals. In one hospital almost all of the participating mothers chose to provide KMC to their infants. We performed an additional analysis excluding this hospital in order to ensure it had not skewed the results, results of this analysis can be found in the supplementary appendix. When we excluded this hospital, compared with mothers in the No KMC group, mothers in the KMC group were still nearly twice as likely to perform exclusive breast milk feeding at discharge (OR=1.61 (95% CI 1.13, 2.31)), and breastfeeding (method) at discharge (OR=1.31 (95% CI 0.92, 1.85)), be providing exclusive breast milk feeding at follow-up (OR=2.51 (95% CI 1.74, 3.62)), and breastfeeding (method) at follow-up (OR=2.61 (95% CI 1.74, 3.93)). As the four hospitals enrolled in the study are all tertiary hospitals with minimal differences in service delivery capacity, we felt it appropriate and useful to compare breastfeeding patterns between mothers and infants in different hospitals, thus we included all four hospitals in our analysis. Given the opportunity we would like to conduct further research to identify any differences between the hospital with the highest uptake of KMC and the other three in order to assess if changes could be made that would increase KMC uptake for preterm newborns.
Thirdly mothers and infants who could not be successfully followed-up were excluded from the analysis, this may have led to selection bias. However, the loss to follow up rate was similar between the KMC and the No KMC group (15.4% vs. 14.5%). Within the KMC group, those lost to follow-up reported a higher exclusive breastfeeding rate at discharge than those who were successfully followed-up (60.0% vs. 54.6%), while within the No KMC group those who were lost to follow up reported a lower rate than those who were successfully followed-up (23.5% vs. 34.6%). This suggests that the results of our analysis may underestimate the association between intermittent KMC and improved breastfeeding outcomes, the actual impact may be greater.
Lastly, the major outcome variables of breastfeeding were only verifiably collected at hospital discharge and self-reported at 42 days follow up. The study would have benefited from a longer term outcome variable, e.g. exclusive breastfeeding at 6-months of age, in order to provide a more robust clinical and public health recommendation.