Oral Sensorimotor Intervention Enhances Breastfeeding Establishment in Preterm Infants

Abstract

Objective:

To assess the efficacy of an oral sensorimotor intervention on breastfeeding establishment and maintenance in preterm infants.

Study Design:

Thirty-one preterm infants born ≤34 weeks gestation were randomized into an experimental or control group. The experimental group received a 15-minute program consisting of stroking the peri-oral structures for the first 5 minutes, tongue exercises for the next 5 minutes, followed by non-nutritive sucking for the final 5 minutes. The control group received a sham intervention for the same duration. The interventions were administered once daily for 10 days. The outcomes included: time to attainment of full oral feeding, breastfeeding acquisition (i.e., ≥50% of direct breastfeeding at hospital discharge), breastfeeding skill assessment using the Preterm Infant Breastfeeding Behavior Scale (PIBBS), length of hospitalization, and breastfeeding maintenance at 3 and 6 months posthospitalization.

Results:

Full oral feeding was attained earlier in the experimental group compared with the control (10.7 ± 2.1 vs. 19.3 ± 3.6 days, p < 0.01). This was associated with a greater number of infants in the intervention group acquiring breastfeeding at hospital discharge compared with the controls (n = 11 vs. 5, p = 0.049). There was no statistical difference in PIBBS score, length of hospitalization, and breastfeeding rates at 3 and 6 months posthospitalization between the two groups (all tests, p > 0.32).

Conclusions:

An oral sensorimotor intervention accelerated the achievement of full oral feeding and enhanced direct breastfeeding rates at hospital discharge only. Provision of an oral sensorimotor intervention is a safe and low-cost intervention that may increase breastfeeding rates in a highly vulnerable population.

Introduction

Human milk is vital in the nourishment of preterm infants.¹ Human milk, as compared with formula, has been shown to decrease the rate of common and life-threatening complications of prematurity, such as sepsis, necrotizing enterocolitis (NEC), and chronic lung disease.¹ These benefits may be improved when human milk is provided directly from the breast rather than bottle feeding expressed milk.¹ Such findings form the basis of the World Health Organization (WHO) statement that calls for exclusive human milk for all infants for at least the first 6 months of life.²

Despite the numerous benefits of human milk, the incidence and duration of breastfeeding in preterm infants continues to be less than that of full-term infants.^3,4 The low breastfeeding rates are attributed to the unique challenges for attaining direct breastfeeding in infants born preterm.^5,6 For effective breastfeeding, the infant must not only extract milk from the breast but also coordinate swallowing and breathing to allow safe transport of the milk bolus from the oral cavity to the digestive system, all while maintaining good cardiovascular stability.⁴ The tongue is the key structure for effective breastfeeding.^7,8 During breastfeeding, the nipple is elongated and there is an initial period of non-nutritive sucking to elicit the milk ejection reflex. Once the milk is ejected, the rate of milk flow may vary. The tongue elongates the nipple and adapts to the milk flow changes during the oral feeding session.^7,8 Infants who are born at less than 34 weeks gestation are developmentally unable to generate and coordinate sucking with swallowing and breathing.⁹

There are an increased number of clinical initiatives to promote breastfeeding in preterm infants.^10,11 However, they are focused primarily on improving maternal education and support. There is a lack of clinical and research strategies aimed at improving oral motor skills associated with breastfeeding in preterm infants. Oral sensorimotor intervention is one such approach. Although substantial evidence supports oral sensorimotor intervention as an effective practice in the enhancement of bottle feeding performance in preterm infants,^12,13 its effect on direct breastfeeding establishment is limited. Findings from two previous studies suggest that a sensorimotor intervention may, indeed, improve breastfeeding rates in preterm infants.^14,15 However, results are biased due to lack of blinding and standardization of the program.^14,15 To date, no studies have investigated the effect of oral sensorimotor input on breastfeeding skills in preterm infants at hospital discharge and posthospitalization. The aim of this study was to assess the efficacy of an oral sensorimotor intervention on breastfeeding establishment and maintenance in infants who are born preterm. Provision of an early oral sensorimotor intervention to increase direct breastfeeding establishment is potentially a safe and low-cost intervention that may increase breastfeeding effectiveness at hospital discharge with the goal of achieving the WHO's recommendations for optimal duration.

Methods

Participants

A total of 36 preterm infants were initially recruited for the study. Infants were enrolled if they were: (1) born at less than or equal to 34 weeks gestational age (GA) as determined by obstetric ultrasonogram and clinical examination; (2) appropriate size for their GA; (3) receiving only tube feedings (orogastric or nasogastric); and (4) whose mothers' intentions were to breast feed and were actively pumping milk at the time of enrolment. Preterm infants with the following chronic medical complications were excluded: (1) bronchopulmonary dysplasia (BPD); (2) necrotizing enterocolitis (NEC); (3) intraventricular hemorrhage (IVH) grades III and IV; (4) periventricular leukomalacia (PVL); and (5) congenital anomalies (e.g., heart, oral, etc.).

Intervention variables

The oral sensorimotor intervention was a 15-minute program, consisting of 5 minutes of oral preparatory stimulation to the cheeks and lips, 5 minutes of tongue exercises (i.e., tongue elevation, depression, extension, and lateralization), and 5 minutes of non-nutritive sucking to integrate the function of the stimulated oral structures. The sham intervention was also a 15-minute program consisting of the researcher placing her hands in the isolette, but not touching the infants. Both programs were administered once a day for 10 days, within a 14-day period. The same researcher administered all the interventions. Before commencing the program, the researcher placed the infant in a supine position in the isolette and ensured that the infant was in an optimal behavioral state (i.e., quiet alert or active alert) to receive the intervention.

Outcome variables

Time to achieve full oral feeding was defined as the number of days to transition from complete tube feeding to full oral feeding (full breast, partial breast/bottle, or full bottle).

Breastfeeding acquisition was described as the number of direct breastfeeding (i.e., infant suckles at breast) received at hospital discharge. Infants who received greater than or equal to 50% of direct breastfeeding at hospital discharge were considered as having acquired breastfeeding. We used 50% as a cut off because as part of standard care preterm infants born ≤1,500 g require supplemental nutrition, and thus a fortifier is added to the human milk for several feeds per day, which can only be taken by bottle.

Breastfeeding skills were monitored by using the Preterm Infant Breastfeeding Behavior Scale (PIBBS).¹⁶ The PIBBS score was selected as an outcome measure because the sensorimotor intervention provided was intended to enhance infants' oral motor skills and ability to breast feed. The PIBBS (1996) consists of a 6-item scale, observing infant's breastfeeding skill including: (1) rooting, (2) how much of the breast was inside the infant's mouth, (3) latching, (4) sucking, (5) longest sucking burst, and (6) swallowing. The scale has an inter-rater reliability range of 0.96–1.0 and good discrimination between infants of different GAs.¹⁶

Length of hospitalization was described as the number of days from admission to hospital discharge.

Duration of breastfeeding was defined as the total number of infants who continued to receive exclusive and/or partial breastfeeding at 3 and 6 months posthospitalization. A survey adopted from the Centers for Disease Control and Prevention Diet History Questionnaire was conducted to inquire about their current feeding status.¹⁷ Information on reasons for stopping to breastfeed, including difficulty with latch/suck, low milk supply, poor weight gain, infant illness, maternal illness/medications, maternal fatigue, return to work, and desiring another feeder for assistance, was monitored. We also gathered information on seeking assistance with breastfeeding, such as with a lactation consultant, feeding clinic, or physician, as well as maternal satisfaction with duration of breastfeeding.

To ensure that results were not biased, the following confounding variables were monitored: infant's GA, birth weight, twin born, ethnicity, postmenstrual age and weight at the start of oral feeding, and severity of illness using the Nursery Neurobiologic Risk Score (NBRS).¹⁸ Further, maternal baseline characteristics were monitored, including age, social services for supplemental financial support, maternal pumping at hospital discharge, and need for nutrient supplementation (i.e., formula) during the study period, all of which are indicators of maternal milk supply.

Procedure

All participants were recruited from the level III NICU at Kingston Health Sciences Centre (KHSC), a tertiary care center in Ontario, Canada. The Health Sciences and Affiliated Teaching Hospitals Research Ethics Board (HSREB) approved the study. The NICU at KHSC has a maximum capacity of 26 beds and cares for ∼400 infants annually. KHSC is striving to become accredited as a Baby-Friendly Hospital Initiative, a global effort advocated by the WHO to encourage exclusive breastfeeding of infants until 6 months of age. As part of the admission history at the KHSC NICU, all mothers are asked about how they intend to feed their child, and this information is recorded in the infant's chart. Although KHSC does not have designated International Board Certified Lactation Consultants (IBCLCs), it does have two members of the nursing staff who are certified as IBCLCs who are available to provide teaching and support of breastfeeding issues in the NICU. At KHSC, no additional lactation support is provided after hospital discharge, such as parents are not provided with breastfeeding pumps or weighing scales as in other institutions. However, before hospital discharge, nurses assess individual family needs by administering a standardized discharge checklist and refer families to social services when supplemental financial assistance is identified.

All infants who met inclusion criteria and whose mother's intention was to breast feed as well as actively pumping milk were approached and verbally explained the study procedure. Written consent to participate was obtained from parents before infants were entered into the study. All infants were randomized into experimental or control groups by using a stratified blocked randomization system with a block size of four. Stratification on GA (<32 and 32–34 weeks) was used to ensure that each group had similar age distributions.

In addition to standard care management, infants in the experimental and control group received the oral sensorimotor or sham intervention, respectively. Interventions were commenced when infants were tolerating 80 mL/kg/day of enteral feeds and for those infants who required nasal continuous positive airway pressure, they were started 24 after its discontinuation. The interventions were provided 15–30 minutes before enteral feeding. A screen was placed around the infant's isolette to blind nurses and family members to group assignment. The interventions were not administered if infants were stimulated or disturbed 30 minutes before the program (e.g., ophthalmological exam) or if infants were medically unstable (e.g., tachycardia). The interventions were stopped if infants had any adverse events, including episodes of apnea, bradycardia, oxygen desaturations, crying, or vomiting during the intervention, and taken up the next day.

In this study, the sensorimotor intervention was intended to enhance infants' oral motor skills and ability to breast feed. Hence, clinical outcomes that are reflective of infants' oral motor skills were selected and monitored at specific times throughout the study period. Specifically, attainment of oral feeding was determined when full oral feeding was achieved on the first of two consecutive days. Breastfeeding acquisition was determined at hospital discharge. Breastfeeding skills (i.e., PIBBS) were assessed on the first week when oral feedings were initiated. Nurses were responsible for initiation and advancement of oral feedings, as well as scoring the PIBBS. All nurses were trained on how to complete the PIBBS and were blinded to group assignment. For this study, pre- and post-weights were not utilized because the amount of milk transferred is associated with an infant's oral motor skills as well as with maternal milk supply, thus confounding the results.

Duration of breastfeeding was monitored at 3 and 6 months after hospitalization by using a 10-minute telephone interview. One interviewer, who was blinded to group assignment, was responsible for all the follow-up questionnaires. The interviewer spoke to the mother of the participant; no other relatives or care providers were sought. The interviewer attempted to contact the participants a total of three times within a 2-week period before and after the 3- and 6-month follow-up date. Unsuccessful attempts were documented.

Statistical analyses

To compare baseline characteristics between groups, an independent-groups t-test was employed. To examine the effect of the oral sensorimotor program versus the sham program on the time to full oral feedings, breastfeeding skills (PIBBS), and length of hospitalization, a univariate analysis of variance with twins born as a covariate included in the model was performed. Fisher's exact test was used to compare the number of infants who acquired ≥50% direct breastfeeding at hospital discharge and the number of infants who received exclusive or partial breastfeeding at 3 and 6 months after hospitalization. Significance was defined at the 0.05 level by using a type I error of 0.05 and a power of 0.80. The sample size for this study was based on the comparison of the oral sensorimotor and sham groups with respect to the time to achieve full oral feeding. The mean length of time to transition from tube to full oral feeding was 14 ± 8 days. A decrease of 1 SD (standard deviation) is considered a clinically significant effect. Thus, a sample size of 32 infants (16 infants per group) was needed. In instances where infants may develop chronic medical conditions such as BPD, NEC, or IVH grades III or IV, an additional 10% of participants were recruited. Hence, a total of 36 (18 infants per group) preterm infants were needed to complete the study.

Results

A total of 36 infants were recruited. However, 3 participants were transferred to another hospital, 1 developed sepsis, and another developed severe BPD leaving a total of 31 participants. Table 1 illustrates that infants in both groups had similar baseline characteristics, with the exception that more infants in the experimental group were twins than controls (p = 0.01). Further, there was no difference in maternal characteristics as well as in the number of mothers actively pumping milk at hospital discharge and need for nutrient supplementation (i.e., formula) during the study period (Table 1). Hence, the results are not confounded by maternal characteristics and maternal milk supply during an infant's hospitalization.

Table 1.

Baseline Characteristics

	Experimental (n = 16)	Control (n = 15)	p^a
Infant characteristics
Gestational age, weeks	32.1 ± 1.6	31.2 ± 2.6	0.50
Birth weight, g	1928.4 ± 453.9	1740.0 ± 478.3	0.66
Gender, male/female	11/5	13/2	0.39^b
Twin born	12	4	0.01
Ethnicity, Caucasian/other/mix	15/1/0	14/1/0	0.96
Received NCPAP	11	12	0.62
Nursery Neurobiologic Risk Score	1.3 ± 1.2	1.8 ± 1.5	0.27
PMA at start of intervention, weeks	33.5 ± 0.9	33.7 ± 0.8	0.70
PMA at start of oral feeds, weeks	34.4 ± 0.5	34 ± 1.6	0.37
Weight at start of oral feeds, g	2,087 ± 275	1,992 ± 677	0.67
Maternal characteristics
Age	28.2 ± 3.3	26.0 ± 7.4	0.28
Received social services	15/1	14/1	0.96
Pumping at discharge	15	14	0.96
Milk supplementation at discharge	4	9	0.48

Data present as mean ± SD or counts.

Independent-groups t-test.

Fisher's exact test.

NCPAP, nasal continuous positive airway pressure; PMA, postmenstrual age; SD, standard deviation.

Infants who received the oral sensorimotor intervention achieved full oral feeding 8 days sooner than those who did not, after adjusting for twin born infants (p = 0.01, Table 2). More infants in the experimental group achieved direct breastfeeding at hospital discharge than in the control group (67% vs. 31%, p = 0.049). However, there was no difference in breastfeeding skills, as demonstrated by the PIBBS score (12.7 ± 2.5 vs. 12.3 ± 3.2, p = 0.56) and length of hospitalization (33.0 ± 15.7 vs. 43.2 ± 27.3, p = 0.054) between the two groups (Table 2).

Table 2.

Breastfeeding Performance and Length of Hospitalization

	Experimental (n = 16)	Control (n = 15)	p^a
Full oral feeding
PMA, weeks	35.8 ± 0.4	36.7 ± 1.8	0.94
Weight, g	2,331 ± 216	2,443 ± 572	0.54
No. of days	10.7 ± 2.1	19.3 ± 3.6	0.01
Acquisition of BF at discharge, n (%)	11 (67)	5 (31)	0.049^b
PIBBS score	12.7 ± 2.5	12.3 ± 3.2	0.56
LOS, days	33.0 ± 15.7	43.2 ± 27.3	0.054

Data present as mean ± SD or counts.

Univariate analysis of variance.

Fisher's exact test.

BF, breastfeeding; LOS, length of stay; PIBBS, Preterm Infant Breastfeeding Behavior Scale.

There was a total of 18 (58%) and 14 (42%) participants who we were able to follow up with at the 3 and 6 month posthospitalization, respectively, with the large majority of participants being in the experimental group (Table 3). There was no longer any difference between groups in the rate of breastfeeding at 3 and 6 months posthospitalization. The main reason for stopping to breastfeed was related to low milk supply for both groups, at the 3- and 6-month follow-up periods. Only five and one mother, in the respective groups, sought assistance with breastfeeding at the 3- and 6-month follow-up. All mothers who had stopped breastfeeding at the 3- and 6-month follow-up period reported that they were dissatisfied with the duration of breastfeeding.

Table 3.

Breastfeeding Duration at 3- and 6-Month Follow-Up

	Experimental	Control	p^a
3-Month follow-up
N	14	4
PMA, weeks	51 ± 1.8	54 ± 5.3	0.01
Weight, g	5,472 ± 735	5,744 ± 2,308	0.02
Exclusive or partial breastfeeding	6	3	0.58^b
Maternal seeking assistance	4	1
Maternal satisfaction with BF duration
Yes	0	1
No	8	0
6-Month follow-up
N	10	3
PMA, weeks	64 ± 2.1	65 ± 0.6	0.08
Weight, g	7,020 ± 888	5,972 ± 761	0.63
Exclusive or partial breastfeeding	5	3	0.23
Maternal seeking assistance	1	0
Maternal satisfaction with BF duration
Yes	0	N/A
No	5	N/A

Data present as mean ± SD or counts.

Independent-groups t-test.

Fisher's exact test.

Discussion

There are many barriers to breastfeeding in the preterm population, which inevitably results in low breastfeeding rates.⁵ Early intervention strategies, which focus on improving infants' oral motor skills required for direct breastfeeding, are needed to enhance current rates.

Our results support our first hypothesis that a targeted oral sensorimotor input can facilitate the transition from tube to oral feeding and enhance breastfeeding rates at hospital discharge. Infants who received the oral sensorimotor intervention achieved full oral feeding sooner than those who did not. These findings are supported by previous studies.^14,15 We observed that these improvements occurred despite similar postmenstrual ages and weight at the first oral feeding between groups. Moreover, the literature indicates that twins, compared with singletons, pose particular challenges to breastfeeding establishment.^19,20 Despite a larger number of infants in the experimental group being twins as compared with the control group in our study, the experimental group overall achieved a higher rate of direct breastfeeding at hospital discharge. Our results illustrate that both groups commenced oral feedings at similar maturities, and that the improved breastfeeding transition and rates are likely due to superior oral motor skills in the experimental group. We anticipated that the experimental group would have better scores on the PIBBS assessment, which is reflective of their breastfeeding oral motor skills. However, we did not observe a difference in oral motor skill between the two groups, in contrast to other studies.^21,22 In this study, infants' oral feeding skills were only assessed once during the first week at the time of initiation of oral feeds. It is possible that further assessments throughout the hospital course would have detected differences in PIBBS scores between groups.

There was statistically no significant difference in length of hospitalization between the two groups. However, infants in the experimental group were discharged 10 days earlier than those in the control group, a difference that is of clinical importance. The large SDs in length of hospital stay reflect the variances in practice in the initiating and planning for hospital discharge among health professionals, and they likely affected the results in this study.

This study has several limitations. Quantitative data on volume of maternal milk supply were not available. However, maternal pumping and need for nutrient supplementation (i.e., formula) during the study period was recorded as an indirect indicator of maternal milk supply. As well, results for assessing the effect of a targeted oral sensorimotor input on breastfeeding duration are limited due to low and largely skewed follow-up data toward the experimental group.²³ A high attrition rate increases the risk of bias, particularly if there is differential attrition between the experimental and control groups,²³ as in our case. However, despite these limitations, our results provide important clinical insights into the potential contributing factors influencing breastfeeding duration in preterm infants after hospital discharge. Although the experimental group had higher direct breastfeeding at hospital discharge than the control group, it appears that the breastfeeding rates decreased and became comparable between the two groups at 3 and 6 months postdischarge. Similarly, other studies have reported a decrease in breastfeeding rates after hospitalization in preterm infants.^6,24 The main reason identified for the cessation of breastfeeding in our participants was attributed to low breast milk supply, which is also corroborated by several other studies.^6,25 Although it was identified as a concern for a select number of participants, difficulties with latch or suck were not the primary reason behind breastfeeding cessation. This finding is clinically significant as it suggests that inadequate milk production, rather than oral motor skills, was a driving force for many parents to transition to formula to ensure adequate nutrition for their infants.

Although being born a twin did not appear to be a confounder for the achievement of direct breastfeeding at hospital discharge, it may have influenced results posthospitalization. We postulate that not only infants who received the intervention had improved oral motor skills, but additionally all mothers received a great deal of nursing support on a daily basis, which likely contributed to the greater achievement with direct breastfeeding until hospital discharge than those who did not receive the intervention. However, this support was no longer available on hospital discharge and we observed that less than 1% of mothers sought assistance for breastfeeding after hospitalization. Moreover, we noted that all mothers who were no longer breastfeeding at both the 3- and 6-month follow-up were dissatisfied with the duration of breastfeeding. These findings suggest that the premature cessation of breastfeeding was not due to a lack of desire from mothers but may be due to a lack of maternal support, thereby creating another barrier to long-term breastfeeding achievement. Indeed, several long-term studies have identified maternal support as a significant factor influencing breastfeeding duration.^6,26 Consequently, we recognize that maternal interventions are crucial in sustaining posthospitalization, the high breastfeeding rates achieved with oral sensorimotor interventions in preterm infants at hospital discharge. Future studies are needed to assess the effectiveness of a dual targeted approach to optimization of breastfeeding, namely both targeting preterm infant oral motor skills and providing pharmacologic and nonpharmacologic breastfeeding support for mothers both during and after hospital discharge.

Conclusions

In conclusion, our results demonstrate that a targeted oral sensorimotor intervention can facilitate the transition from tube to oral feeding and enhance direct breastfeeding rates at hospital discharge in preterm infants. Although our follow-up results are limited in their number, and therefore their ability to extrapolate to a broader preterm population, they suggest that the impeding factor in continuing breastfeeding is not solely related to the infants' oral motor skills but also influenced by maternal factors. Our findings support that the provision of an oral sensorimotor intervention is a safe and low-cost intervention that may increase breastfeeding rates in a highly vulnerable population.

Footnotes

Disclosure Statement

No competing financial interests exist.

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