Q. My married daughters are Kolel wives. Two questions: 1) When one shops with her infant child sleeping in the stroller, often she places food items in the stroller below the sleeping child. Is this a problem?
A. On question 620 regarding food placed an El Al night flight, in the pocket of the seat in front, when probably most passengers are Jewish, we wrote:
"Talmud (Pesachim 112a) and Shulchan Aruch Y.D. (116: 5) mention that food and liquids placed under the bed, ruach ro’oh or a harmful spirit will rest on them, even when covered, and therefore one should avoid placing them there. Pischei Teshuvos (ibid. 4) quotes Shvus Yaakov. that after the fact, they are permitted, others are stringent.
There are also other limitations to this proscription mentioned by various Poskim. Maggen Avraham quoted by Mishna Berura (173: 4) writes that the natural world has changed, and in our times these restrictions may not apply; Hagra and others remain strict. The Ran (Pesachim ibid.) mentions that this applies only to cooked food. Mizmor Ledavid (110) Yafe Lalev (3: 116: 6) maintain that it is restricted to food placed only on uncovered ground or earth, not on land covered by stones or wooden floors etc.. Therefore, Yabia Omer (Y.D. 1: 9, O.H. 9: 95) is lenient of food left on pockets, when one fell asleep. He suggest to wash them three times if possible. Shalmas Chaim (2: 7) adds that it applies only to a bed, therefore children’s bottles left under their carriage are permitted. Shevet Halevy (quoted in Avnei Yashfa 141) asserts that when double wrapped the food is permitted. (as in a bag placed inside a seat pocket). He also maintains that it may not apply to sleeping during the day.
Taking into account all the above and the fact that food placed on an angle in the back of a plane seat, can hardly be considered under, Horav Shlomo Miller’s Shlit’a opinion is that you can eat the food."
The same would apply in your case
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit’a
See Shu"t Minchas Yitzchok vol. 4 siman 117 where he discusses this very question and seems to say that since the child is below bar/bas mitzva, it is not a problem.