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Recommendations Summary

CF: Infant Feeding 2020

Click here to see the explanation of recommendation ratings (Strong, Fair, Weak, Consensus, Insufficient Evidence) and labels (Imperative or Conditional). To see more detail on the evidence from which the following recommendations were drawn, use the hyperlinks in the Supporting Evidence Section below.

  • Recommendation(s)

    CF: Infant Feeding

    In infants diagnosed with cystic fibrosis (CF), the RDN or international equivalent should recommend providing as much breast milk as possible, with breast milk fortification and formula supplementation as necessary for the first year of life, to regain birthweight z-score and achieve normal growth for age. Breastfeeding is associated with improved forced expiratory volume in one second (FEV1%) predicted and decreased antibiotic use, but supplementation may be needed for infants with high nutrient requirements.

    Rating: Fair

    • Risks/Harms of Implementing This Recommendation

      There are no obvious risks or harms associated with this recommendation. For the general population, exclusive breastfeeding during the first six months of life and any breastfeeding for up to two years of age and beyond is recommended to optimize infant health outcomes (World Health Organization 2019). However, higher nutrient requirements in infants with CF may require additional nutrients through breast milk fortification or supplementation with formula in order to prevent undernutrition (Lai et al 2016), which is associated with pulmonary decline throughout life (Academy of Nutrition and Dietetics 2019).

    • Conditions of Application

      Beliefs about and Feasibility of Breastfeeding. Ability and desire to breastfeed may be affected by personal values and preferences, work environment, convenience, and limitations resulting from managing CF itself. For those with inadequate resources or socioeconomic disparities, breastfeeding may be more difficult to achieve or sustain. Therefore, the RDN should work with the families of infants with CF to determine how breastfeeding can be optimized as well as if and how much fortification/supplementation is optimal according to individual infant needs, in conjunction with mother’s/family’s values and lifestyle.

    • Potential Costs Associated with Application

      This recommendation is not associated with any obvious costs beyond normal costs of feeding an infant with cystic fibrosis (CF), which may be higher compared to an infant without CF due to added fortification and supplements.

    • Recommendation Narrative

      Background. Breastfeeding is associated with many positive outcomes in healthy infants, including decreased risk of asthma, obesity, type 2 diabetes, and respiratory and gastrointestinal infections (Division of Nutrition 2019). Therefore, encouraging breastfeeding in all infants is considered standard practice. Providing breast milk to infants with cystic fibrosis (CF) may be of particular importance since CF increases risk of inflammation and infection (Roesch et al 2018), and breastfeeding is known to enhance the immune system (Palmeira & Carneiro-Sampaio 2016).  

      Evidence. Observational evidence reported that infants with CF who were breastfed for at least 4-6 months, exclusively or partially, had higher FEV1% predicted at ≥6 years compared with infants who were exclusively formula fed (Colombo et al 2007, Parker et al 2004). In infants with CF, one large, cross-sectional survey study reported that breastfeeding exclusively for ≥6 months was associated with a decrease in IV antibiotic use over the 2 years prior to data collection compared to no breastfeeding, though there was no significant benefit noted with non-exclusive or shorter breastfeeding duration (Parker et al 2004). However, in infants with CF, the cause and effect relationship between breastfeeding and pulmonary function remains unclear. More severe CF, which is associated with more severe complications and/or co-morbidities, may lead to less exclusive breastfeeding since these infants may not be gaining weight appropriately and are therefore more likely to be supplemented with formula.

      In infants with CF, limited evidence was mixed regarding the influence of infant feeding modality on weight and length gain. Two cohort studies reported no significant differences in weight gain or weight-for-age z-scores between breastfed and formula-fed infants (Colombo et al 2007, Munck et al 2018, Leung et al 2017) even when considering exclusivity (Colombo et al 2007, Leung et al 2017). However, one study reported a significant decline in weight z-scores from birth to 2 years of age, particularly from 2-6 months, for infants who had been exclusively breastfed for ≥2 months, though there were no changes in other feeding groups (Jadin et al 2011). Breastfeeding duration and exclusivity did not influence length gain (Colombo et al 2007, Munck et al 2018, Leung et al 2017, Jadin et al 2011).

      Strong evidence from the systematic review supporting this guideline demonstrated that, in pediatric participants with CF, regaining birthweight z-score by age two and maintaining BMI and height z-score throughout childhood was associated with the highest FEV1% predicted later in life compared to those who did not regain and maintain z-scores (using CDC growth charts). Participants who maintained a weight, length, weight-for-length and BMI >50%ile from infancy and early childhood had better FEV1% predicted values. In general, normal growth parameters during childhood were associated with increased FEV1% predicted in long-term follow-up studies (Darrah et al 2016, Emerson et al 2002, Goss et al 2018, Keller et al 2003, Konstan et al 2007, Lai et al 2009, Machogu et al 2015, McPhail et al 2008, Sanders et al 2014, Sanders et al 2015, Sanders et al 2015, Sanders et al 2018, Usatin et al 2017, Welsh et al 2014, Woestenenk et al 2014, Yen et al 2013). Since WHO growth charts are less likely to classify children as being underweight compared to CDC growth charts, it is suggested practitioners use a cut-off value of 70%ile when using WHO growth charts.(Machogu et al 2015, Zhang et al 2015). Though it is clear that early weight and growth parameters are associated with FEV1% predicted 4-16 years later, there was also evidence that early pulmonary function was associated with prospective growth (Goss et al 2018). Therefore, the influence of growth and nutrition status and pulmonary function appears bi-directional in CF, with poor nutrition status leading to more rapid decline in pulmonary function, which, in turn, leads to higher energy and nutrient needs to cope with impaired lung function while supplying oxygen needs for the body. Therefore, aiming to maintain or achieve optimal nutrition status from birth forward is an important factor in maintaining lung function later in life.

      Newborn screening for CF has had a considerable impact on nutritional status as most CF infants were previously diagnosed after failing to thrive.  Evidence from eras prior to newborn screening may be biased in that infants who were breastfed had higher FEV1% predicted because infants with more severe disease and failure to thrive were more likely to begin formula feeding. Guidance on PERT for infants was outside the scope of this guideline but can be found in other contemporary guidelines (Saxby et al 2017, Turck et al 2016).

      Breastfeeding Support. Support systems in place for breastfeeding may be available through the hospital or through community services such as the Women, Infants and Children (WIC) program. For mothers of infants with CF who are willing and able to breastfeed, RDNs can encourage and support breastfeeding and can connect the family with resources such Lactation Consultants or breastfeeding Peer Counselors. RDNs should work with the interdisciplinary health care team to frequently track the growth and evaluate the nutrition status of the infant with CF to determine if breast milk fortification or supplementation is necessary to achieve or maintain growth that is consistent with birthweight z-score and normal growth for age.

    • Recommendation Strength Rationale

      The evidence supporting the recommendation on infant feeding was based on two different research questions. Grade III evidence described that breastfeeding, including exclusive breastfeeding, may result in improved FEV1% predicted and decreased antibiotic use, but may result in sub-optimal growth. There are many confounding relationships that need to be addressed in this literature, and conclusions may change with more high-quality evidence. Grade I evidence described that maintaining weight z-scores throughout infancy and childhood resulted in the most optimal FEV1% predicted outcomes later in life.

    • Minority Opinions

      Consensus reached.