Check out the description here: appropedia.org/Printable_Breast_Pump. Sorry, these are SolidEdge Academic Files, so they will not be able to open on commercial software. Also, don't use these to make money, or else the people at SolidEdge may get angry.
I have uploaded .stl files as well. Happy printing! I am trying to find a better thread design, as this was adapted using measurments taken from a bottle. If anybody has seen a public domain model that is actually made by a company that produces these things, let me know!