Bottle Nipple Flow Rates
by Anne Eglash MD, IBCLC, FABM
I am frequently asked by parents, particularly breastfeeding mothers, ‘What is the best nipple for feeding my baby a bottle?’ For infants with oral feeding challenges, such as prematurity, cleft palate, or heart disease, speech therapists often decide what nipples to use, and they work with the infant and family to make sure that the bottle and nipple are appropriate. But what about term healthy infants who are breastfeeding, who may need to bottle feed in the future?
I often consider the shape of nipples and flow rate. My personal preference is to suggest a nipple that is cylindrical. I suspect that a flat or bulbous shaped nipple may keep the tongue back when feeding, while during breastfeeding, the tongue needs to protrude to grasp and maintain contact with the breast.
The article for this week’s clinical question of the week addresses flow rate of different nipples. The authors explain that flow rate matters because swallowing interrupts breathing. If flow rate is too fast, respirations are more frequently interrupted. Healthy term infants can modify how strongly or quickly they are sucking to control the flow rate to some extent, whereas infants with prematurity or other challenges such as heart disease or lung disease have more difficulty moderating the flow rate with a given nipple, and are at higher risk for respiratory distress, choking and aspiration.
This study tested the rate of milk flow from bottle nipples commonly used in the hospital or after discharge, for a total of 375 nipples. They compared the flow rate of nipples in a few different ways: 1) comparison between the exact same type of nipple, and 2) comparison between nipples marketed in the same category, such as extra slow flow nipples.
They hooked up the bottles of milk to a Medela pump using the proper shield sizes at a controlled angle, applying the same pressure each time, and measured the flow rate.
- The nipple with the fastest flow rate is the Medela Calma nipple.
- All of the nipples marketed as ‘slow flow’ had very similar flow rates.
- Products labeled as ‘premature’ nipples were slower flow than the ‘slow flow’ nipples.
- The packaging for nipples tends to be accurate in its description for rate of milk flow.
- In general, each nipple of a particular type (i.e. all Gerber First Essential Nipples) have nearly the exact same flow rate.
See the Answer
Milk flow rate may play an important role in an infant’s ability to safely and efficiently coordinate sucking, swallowing, and breathing during feeding.
To test milk flow rates from bottle nipples used in the hospital and after discharge.
Bottle nipples used in hospitals (10 unique types) and available nationwide at major retailers (15 unique types) were identified. For each of the 25 nipple types, 15 nipples of that type were tested by measuring the amount of infant formula extracted in 1 minute by a breast pump. Mean milk flow rate (mL/min) and coefficient of variation (CV) were calculated for each nipple type. Comparisons between nipple types were made within brand and within category (e.g., Slow, Standard). A cluster analysis was conducted to identify nipples of comparable flow.
A total of 375 individual nipples were tested. Milk flow rates varied widely, from 0.86 to 37.61 mL/min. There was also a wide range of CVs, from 0.03 to 0.35. Packing information did not accurately reflect the flow rates of bottle nipples. The cluster analysis revealed 5 clusters of nipples, with flow rates from Extra Slow to Very Fast.
Implications for Practice
These data can be used to guide decisions regarding nipples to use for feeding infants with medical complexity in the hospital and after discharge.
Implications for Research
Research on infant feeding should consider the flow rate and variability of nipples used, as these factors may impact findings.
This study has important implications for practice:
- Don’t trust the label on the package! For example, the flow rates of bottles that are in the same category as ‘slow flow’ will differ significantly.
- Preemie nipples are not slower than slow flow nipples.
- The slowest flow nipple, among those studied, is the Phillips Avent Natural First Flow. The fastest by a huge margin is the Medela Calma.
- When comparing the exact same nipple brands/type, the nipple with the most variability in flow, is the Phillips Avent Natural First Flow, but the majority of the nipples had a high degree of variability.
- Obtain this article and use this information to guide families on appropriate nipple brands to match infant needs.
- Don’t over-tighten the nipple collar onto the bottle. This can lead to negative pressure and nipple collapse, affecting milk flow.
- Adding a high volume of milk in the bottle will cause the milk to flow at a higher rate due to hydrostatic pressure. So, if feeding a frail preemie, don’t put much more in the bottle than the infant is going to take. Pacing the feeding, by keeping the bottle horizontal, helps to decrease the hydrostatic pressure.
- And, holey moley, some of the nipples studied didn’t even have a hole!