Abstract: Breastfeeding a child on the Sabbath and Jewish holidays is permitted without any restrictions. However, expression of milk into a receptacle for later use is a serious halachic transgression. Therefore, expressing milk on these days in the normal manner is not permitted. When the mother is in pain, or suffering from mastitis, she can pump in a manner that will let the milk go to waste. When the child requires expressed milk, an individual question should be asked. In cases where pumping is permitted, electric machines can be operated with a timer.
Discussion: Breastfeeding a child is permitted on the Sabbath and Jewish holidays without any restrictions. Expression of breastmilk, however, raises a number of issues in Jewish law. Therefore, expressing milk on these days in the normal manner is not permitted. However, as in most areas of Jewish law, serious risk to health takes precedence over the rules of Sabbath and holidays. Therefore, in certain circumstances, expression is permitted. For example, where there is severe discomfort due to engorgement or mastitis  , the mother is generally advised to express the milk in a way that ensures it cannot be used. Expressing milk in this manner is permissible if needed to alleviate suffering .
To understand the issues related to breastmilk expression the Sabbath and holidays, it is important to have a bit of a background.
Removal of milk on the Sabbath and holidays (other than by direct nursing) is a biblical prohibition. Therefore, even manual pumping is a concern.
The biblical prohibition applies if the milk is collected in a vessel or if it will be used. Therefore, expressing milk in a such a way that it goes directly to waste does not violate the biblical prohibition. However, it is not allowed at the lower level of a rabbinic prohibition.
Cases of endangering life allow overriding even biblical prohibitions (although, where possible, it is preferable to modify an activity so that only a lower-level rabbinic prohibition is violated)
Cases of suffering can override rabbinic prohibitions
The practical implications of this are:
If the issue is pumping for premature or ill infants where there clearly is a life threatening issue, any pumping should be permitted. It would be better to reduce the prohibition to a rabbinic level by employing one of two strategies
Getting a special switch known in the trade as a “grama switch” (may be available in Jewish community). This causes a delay in the electric circuit so the person turning on the machine is doing so indirectly. This reduces the prohibition to a rabbinic level and thus makes it easier to permit.
Using a standard electric timer with pins that indicate the time it will go on and off. The mother should have the flanges on her breast before the machine is turned on. This also reduces the prohibition to a rabbinic level and makes it easier to permit.
If the issue is pumping for a baby who needs the milk but where there is not a clearly life threatening situation, there may be debate between rabbis. The issue is their understanding of the importance of breastmilk in the particular case . This is where a physician’s opinion can be helpful. Most rabbis, if given the proper understanding, would allow pumping where the prohibition has been reduced to a rabbinic level by one of the two techniques outlined above.
If the issue is maternal suffering only (mastitis, not the need for the milk), a clearly allowed method is to hand express over the sink or toilet (where milk is clearly not collected for use) or if using a pump (either manual or electric with the techniques above) putting dish soap in the collection container before pumping (so the milk will clearly not be used).
Implications for Patient Care:
Expression of breastmilk may be needed for the care of the mother or the child patient. Expression can be permitted on the Sabbath and holidays if the appropriate conditions are met. Specific cases should be discussed in advance of the Sabbath or holiday with a halachic authority. When a woman is advised to express breastmilk, she should be given a clear explanation as to the need for this intervention, preferably in writing, with which she can turn to her halachic advisor. It is important that the explanation include the consequences to mother (e.g., mastitis and pain) of not pumping and to the child (e.g., lack of receiving breastmilk) if she does not pump during this time period.
 Amir LH. The Academy of Breastfeeding Medicine Protocol Committee. ABM clinical protocol # 4: mastitis, revision, May 2008. Breastfeed Med. 2008;3(3):177-180.
 Amir LH1, Trupin S, Kvist LJ. Diagnosis and treatment of mastitis in breastfeeding women. J Hum Lact. 2014 Feb;30(1):10-3. doi: 10.1177/0890334413516065.
 Mass S. Breast pain: Engorgement, nipple pain and mastitis. Clin Obstet Gynecol 2004;47(3):676-82.
 American Academy of Pediatrics. Breastfeeding and the use of human milk. Published on line Feb 27, 2012. www.pediatrics.org/cgi/doi/10.1542/peds.2011-3552.