I remember seeing this movie when I was young which puts it late 70s or early 80s. It could have been made earlier in the 70s though. I remember that it was about a single mom who needed to work nights on an assembly line. I am fairly certain she was a union worker. This mom would put her baby to bed and leave it alone while she worked the night shift. The baby was still in a crib maybe 10 months old. I remember the scene where another woman comes up to her during her shift and tells her the child died in a fire. The mother gets upset and starts crying but does not leave her spot on the assembly line because she needs the money and there is nothing she can do about it.