The socialite has been using a breast pump to get milk for her two-month-old son Phaedra, who she has with her musician husband Tom Cohen.
She tweeted: "Thanks @Medela_UK my new Swing pump has arrived this morning and is an absolute life saver. #breastfeeding #breastisbest."
A pump is used to express breast milk which is often bottle fed to the child by a caregiver, and while it enables mothers to go back to work, many consider the method unnatural.
Lily Allen - who breast fed both her daughters - was quick to respond to Peaches' tweet, writing: "@peaches_g @Medela_UK pumping n dumping eh ? (sic)"
While Peaches - who also has 14-month-old son Astala - is yet to respond, outspoken Lily's comment angered other mothers on the social networking site.
User MerylORourke pointed out a breast pump is a crucial tool for women who need to return to work and want to keep breastfeeding their baby.
She ranted: "I breast feed full time and work part time, need the pump to keep supply + milk there for baby /
Also many women have problems with supply and use pump to increase it. Of all the things to criticise / when I went back 2 work many followers asked me how to pump as most had intended stopping. He's 12 mns (sic)".
Lily, 28, has been vocal about her motherly duties in the past when feeding her daughters Ethel, 19 months, and six-month-old Marnie, sharing details of her leaking breast milk.
She tweeted: "I feel sick and I left the house without breast pads and started leaking all over myself at the #Wolsley .oh and I wiped out in the street earlier #glam (sic)."