Donna T. Ramsay

Volume and Frequency of Breastfeedings and Fat Content of Breast Milk Throughout the Day

OBJECTIVE. We aimed to provide information that can be used as a guide to clinicians when advising breastfeeding mothers on normal lactation with regard to the frequency and volume of breastfeedings and the fat content of breast milk. METHODS. Mothers (71) of infants who were 1 to 6 months of age and exclusively breastfeeding on demand test-weighed their infants before and after every breastfeeding from each breast for 24 to 26 hours and collected small milk samples from each breast each time the infant was weighed. RESULTS. Infants breastfed 11 ± 3 times in 24 hours (range: 6–18), and a breastfeeding was 76.0 ± 12.6 g (range: 0–240 g), which was 67.3 ± 7.8% (range: 0–100%) of the volume of milk that was available in the breast at the beginning of the breastfeeding. Left and right breasts rarely produced the same volume of milk. The volume of milk consumed by the infant at each breastfeeding depended on whether the breast that was being suckled was the more or less productive breast, whether the breastfeeding was unpaired, or whether it was the first or second breast of paired breastfeedings; the time of day; and whether the infant breastfed during the night or not. Night breastfeedings were common and made an important contribution to the total milk intake. The fat content of the milk was 41.1 ± 7.8 g/L (range: 22.3–61.6 g/L) and was independent of breastfeeding frequency. There was no relationship between the number of breastfeedings per day and the 24-hour milk production of the mothers. CONCLUSIONS. Breastfed infants should be encouraged to feed on demand, day and night, rather than conform to an average that may not be appropriate for the mother-infant dyad.

Anatomy of the lactating human breast redefined with ultrasound imaging

The aim of this study was to use ultrasound imaging to re‐investigate the anatomy of the lactating breast. The breasts of 21 fully lactating women (1–6 months post partum) were scanned using an ACUSON XP10 (5–10 MHz linear array probe). The number of main ducts was measured, ductal morphology was determined, and the distribution of glandular and adipose tissue was recorded. Milk ducts appeared as hypoechoic tubular structures with echogenic walls that often contained echoes. Ducts were easily compressed and did not display typical sinuses. All ducts branched within the areolar radius, the first branch occurring 8.0 ± 5.5 mm from the nipple. Duct diameter was 1.9 ± 0.6 mm, 2.0 ± 90.7 mm and the number of main ducts was 9.6 ± 2.9, 9.2 ± 2.9, for left and right breast, respectively. Milk ducts are superficial, easily compressible and echoes within the duct represent fat globules in breastmilk. The low number and size of the ducts, the rapid branching under the areola and the absence of sinuses suggest that ducts transport breastmilk, rather than store it. The distribution of adipose and glandular tissue showed wide variation between women but not between breasts within women. The proportion of glandular and fat tissue and the number and size of ducts were not related to milk production. This study highlights inconsistencies in anatomical literature that impact on breast physiology, breastfeeding management and ultrasound assessment.

Response of Breasts to Different Stimulation Patterns of an Electric Breast Pump

To test the effect on milk ejection, an electric breast pump was programmed to provide pumping patterns with frequencies of 45 to 125 cycles/min and vacuums of -45 to -273 mm Hg. The time taken for milk ejection to occur (measured using ultrasound to detect a dilation of a lactiferous duct in the opposite breast) in response to the current Medela electric breast pump pattern (45 cycles/min) was 147 ± 13 s. For patterns that more closely resemble the sucking frequency of an infant when it first attaches to the breast, milk ejection occurred between 136 ± 12 and 104 ± 10 s, although this difference was not statistically significant. Milk ejection in response to breastfeeding occurred after 56 ± 4 s. The applied vacuum affected the amount of milk that was removed up to 50 to 70 s after milk ejection but not the time for milk ejection. J Hum Lact. 19(2):179- 186.

The Use of Ultrasound to Characterize Milk Ejection in Women Using an Electric Breast Pump

This study aimed to use ultrasound imaging to investigate the milk ejection characteristics of women during a 10-minute expression using an electric breast pump capable of applying 2 markedly different vacuum patterns. The classic pattern (47 cycles/min) and 3-phase pattern (pre-milk ejection: 120 cycles/min, post-milk ejection: 20 cycles/min for 2 minutes post-milk ejection then 55-78 cycles/min for 8 minutes) were tested, and the milk expressed was collected in 30-second intervals. Multiple milk ejections (96%) were detected (classic: 3.27 ± 2.05; 3-phase: 3.72 ± 1.19) and associated with increases in milk flow. Almost half of the total volume of milk expressed was removed during the first milk ejection (classic: 41.38 ± 21.48%; 3-phase: 46.72 ± 26.60%). There was no correlation between the number of milk ejections and both the total volume of milk and percentage of available milk for either pattern. In conclusion, milk ejection characteristics and efficiency of milk expression did not change in response to different expression patterns.

Identification of Factors Affecting Breast Pump Efficacy

Many studies have investigated the physical characteristics of sucking by breast- and bottle-fed infants (Woolridge 1986; Weber et al. 1986; Mathew & Bhatia 1989; Bamford et al. 1992). However, none have applied the same approach to human milk expression using an electric breast pump. In this regard there is a paucity of information regarding factors that can affect breast pump function. We have developed a method suitable for the objective determination of breast pump efficacy (Mitoulas et al. 2002a) and have used this method to compare a standard pumping pattern to an experimental pumping pattern in an effort to identify factors that may be responsible for breast pump efficacy.