My father told me that his mother used to tell him about an old hispanic superstition and ritual that when you are at a baby shower a woman must thread a needle then have the pregnant woman lie on her back on the floor and someone must hold the thread above the woman’s stomach. The thread is said to move as soon as it is hovering over the belly, and whichever way it swings decided the sex of the baby. If the thread swings to the left then the woman is supposed to be having a boy and if the thread swings to the right then the woman is supposed to have a girl.

I believe that this is just another game played at baby showers that is supposed to guess the sex of a baby for fun.