Re: “Education and Experiences of Antenatal Breast Milk Expression: A Systematic Review” by Sobik et al.

To the Editor

We read with interest the “Education and Experiences of Antenatal Breast Milk Expression: A Systematic Review.” ¹ The authors conducted a systematic review of Antenatal Breast Milk Expressing (ABME) for evidence of the benefits, risks, and impact of ABME on the maternal–infant breastfeeding dyads.

In the Introduction, the statement “Antenatal breast milk expression (ABME) is a method used to prepare the breast for breastfeeding” cites a study by Singh et al. ² In their study of 180 women randomly assigned to daily expression from 37 weeks, time to “full lactation” (defined as “when no top feed was required”) was reported as <1/2 hour in 95% of the study group compared with 70% in the control group). This definition of full lactation is not consistent with definitions as used in most practice and research. ³ We question the use of this study as evidence—even anecdotal—that ABME increases milk supply and prevents delay in lactogenesis. ¹

Sobik et al. used a tool for assessing quantitative studies (the National Collaborating Centre for Methods and Tools Quality assessment tool) for all 10 studies in their review. ¹ It is clearly inappropriate to use a quantitative tool to assess the quality of qualitative research studies, so Table 3 requires revision.

Table 4 displays the results of average milliliters expressed per ABME session. ¹ However, the volumes in Forster et al. ⁴ were a median of 5.5 mLs total expressed (range 0–905, IQR 0–22) not per expressing session and the median number of episodes was 20, which was omitted in this systematic review. In Moorhead et al., ⁵ the volume of 0.7 mLs in the table appears to be the total volume of the 10 women in the qualitative study [172 mLs] divided by 10 women = 17.2 mL/woman and divided by the median frequency of expressions [22.9] = 0.75 mLs. This was a study that included only women from the study by Forster et al., ⁴ and the women are already included in the review and, therefore, should not be included twice. Furthermore, we purposively sampled women with high and low volumes, and calculating an average is not meaningful.

In conclusion, we hope that the readers will understand that stating that ABME prepares the breast for breastfeeding is a non-evidence-based statement. We appreciate the efforts to synthesize the available data, identify various study's strengths, and the variation in experience of ABME for women. However, readers should be cautious, and be aware that the volumes cited are an overestimate and the perceived benefits may not exist.