Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter to the Editor
  • Published:

Breast milk: the best lovebiotic

Journal of Perinatology volume 35, page 665 (2015)Cite this article

Subjects

We read with interest the recent article by Cibulskis and Armbrecht1 describing the association of metabolic acidosis in premature infants fed on breast milk fortified with liquid fortifier. As our neonatal unit has reached 100% breast milk exposure to extremely low birth weight (ELBW) and 90% for very low birth weight (VLBW) infants through a quality improvement project,2 we are keen on the author’s observations. However, we wish to share some reservations regarding the methodology adopted to arrive at the associations and conclusions:

  1. 1)

    There is considerable room for selection bias between the two groups being compared. Two consecutive patient populations were selected at different time periods by block allocation.3 A number of potential confounders, that could have influenced the study results, were left to the treating clinician’s discretion. Generally a good randomisation process achieves groups that are similar in baseline characteristics, and thereby minimises confounding and type-1 errors that could lead to misleading results.4

  2. 2)

    Sufficient information is not provided on the acid–base status of the infants prior to administration of the liquid human milk fortifier (HMF). We also have no visibility in the paper of some key co-morbidities or pharmaceutical agents that might have contributed to metabolic acidosis, for example, sepsis, significant patent ductus arteriosus or regular medications with acidic pH such as caffeine citrate.

  3. 3)

    No institutional feeding guidelines have been explained or given as an appendix in the paper, and no clear values proposed advising clinicians regarding at what level of base excess/pH the HMF should be discontinued.

  4. 4)

    There is no logistical regression done and as such no association could be precisely deduced between metabolic acidosis and use of the HMF. When one nominal variable (dependent) and one measurement variable (independent) are in question, we would like to know whether variation in the measurement variable causes the variation in nominal variable. We do recognise that the authors did not attempt a causation hypothesis; however, the overall methodology permits only a weak association at the best.

There is considerable room for selection bias between the two groups being compared. Two consecutive patient populations were selected at different time periods by block allocation.3 A number of potential confounders, that could have influenced the study results, were left to the treating clinician’s discretion. Generally a good randomisation process achieves groups that are similar in baseline characteristics, and thereby minimises confounding and type-1 errors that could lead to misleading results.4

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

References

  1. Cibulskis CC, Armbrecht ES . Association of metabolic acidosis with bovine milk-based human milk fortifiers. J Perinatol 2015; 35: 115–119.

    Article  CAS  Google Scholar 

  2. Philip R, Ismail A, Quinn C, Dunworth M, Hannigan A, O’Leary M . A ‘NEC free NICU’ through breastfeeding quality improvement project (QIP). Pediatrics 2015; 135 (Suppl 1): S13.

    Article  Google Scholar 

  3. Philip RK . Power of numbers versus number of powers. Arch Dis Child 2008; 93 (7): 637–638.

    CAS  PubMed  Google Scholar 

  4. Sedgwick P . Standard deviation or standard error of the mean. BMJ 2015; 350: h831.

    Article  Google Scholar 

  5. Moya F, Sisk PM, Walsh KR, Berseth CL . A new liquid human milk fortifier and linear growth in preterm infants. Pediatrics 2012; 130 (4): e928–e935.

    Article  Google Scholar 

  6. Hagadorn JI, Brownell EA, Lussier MM, Parker MG, Herson VC . Variability of criteria for pasteurised donor human breast milk use: a survey of US Neonatal ICU Medical Directors. JPEN J Parenter Enteral Nutr 2014 Sep 29 PMID: 25267184 (e-pub ahead of print).

Download references

Author information

Authors and Affiliations

  1. Division of Neonatology, Department of Pediatrics, University Maternity Hospital Limerick, Limerick, Ireland

    M R Crealey, E Ludusan & R K Philip

Authors
  1. M R Crealey
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. E Ludusan
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. R K Philip
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to R K Philip.

Ethics declarations

Competing interests

The authors declare no conflict of interest.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Crealey, M., Ludusan, E. & Philip, R. Breast milk: the best lovebiotic. J Perinatol 35, 665 (2015). https://doi.org/10.1038/jp.2015.59

Download citation

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/jp.2015.59

This article is cited by

Search

Advanced search

Quick links