When it comes to breast pumps, we need to stop viewing vacuum strength (suction) as the determining factor of a good pump. In fact, strong pump suction can cause permanent nipple damage and decreased milk supply. As breastfeeding professionals, we are all here to help parents reach their breastfeeding goals, and it is our goal to demonstrate how pump vacuum strength has incorrectly become the standard by which many professionals and mothers alike assess a well-performing breast pump. 

We know from research done by Einar Egnell, a Swiss engineer, that a baby’s suck pattern is 220-230mmHg (millimeters of mercury) (Egnell, 1956). However, many popular pump brands operate with a vacuum range well above the standard suck pattern, around 270mmHg at the highest setting. In speaking to mothers and listening to mothers’ commentary on social media, most will immediately turn their pump vacuum strength to the highest setting (270mmHg), thinking that it will help “suck out more milk”. At this setting, nipple tissue damage, long term nerve damage, and low milk output are common occurrences.

In contrast, Ardo’s Calypso operates at vacuum range of 250mmHg. With this vacuum strength, the Calypso is gentler on the milk ducts found near the areola. By slowly pulling the mother’s nipple into the flange and then gently releasing the nipple, a ‘negative pressure’ environment is created and the mother does not experience an intense “snapback” effect, common among popular pump brands. Our unique pump design allows the Calypso to mimic a baby’s true suck, therefore granting appropriate nipple stimulation and nerve conduction, which ultimately leads to increased letdown reflexes.

When working with parents in reaching their breastfeeding goals, the topic of vacuum strength should not be overlooked. Correct operation of vacuum strength can be the deciding factor of a mother successfully pumping for her baby.



Egnell, E. The mechanics of different methods of emptying the female breast. Journal of Swedish Medical Association 40, 1-8, 1956.