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Thinking you will be sticking out because of a black bag on your back is survival forum paranoia. And no offence, but a middle aged pregnant woman is going to stick out slightly in a crowd and it will not be because of your pack. It could be black, pink or with glowing lights and a large sponge bob mural across it.
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It looks like a school bag really.
Second the pregnant women comment, but I want to qualify the backpack comment. IMHO, stuff that is overtly "tactical", i.e. digicam, covered with molle loops, etc. tends to stand out.
FWIW, the diaper backpack I'm getting for my little ones is red with a reflective stripe. The idea is visiblity to prevent getting turned into bumper meat by an inattentive motorist. Also, sternum straps are worth their weight in gold.