According to Parenting.com, there are several small indicators believed to predict that a woman is carrying a male child, such as having a low pregnancy bump or seeing a Doppler heart reading of less than 140 beats per minute at a doctor's check-up. Male children are believed to create cravings for salty and sour foods during pregnancy, and it is believed (though not true) that women are less prone to morning sickness with boys.
Parenting.com explains that there are additional tests that a woman can take to test the sex of her baby. One example is for a woman to urinate in a cup and mix in a small amount of Drano to see if the color of the urine changes. A blue reaction is believed to indicate that she is pregnant with a boy. Women can also tie their wedding band to a string and dangle it over their pregnancy bump to see which way the ring swings. Circular movements are thought to signal that a boy is on his way. Friends of a pregnant woman can join in by placing a key in front of her on a tabletop to judge how she picks it up. If she chooses the larger end of the key, she is supposed to have a boy. Of course, this test does not work if the woman is aware of how it works.