personally I don't think there's anything in it, probably just a coincidence when people get it right. With my first everyone thought it would be a boy coz i had a neat round bump, all at the front- but I had a girl. second and third times, carried with a wide bump- both girls! this time- neat and round again but we already know it's a girl! guess I just don't carry boys- but I had 3 pretty trouble free pregnancies and births and have 3 gorgeous little girls to show for it and I wouldn't trade them for the world! baby no 4 due in little over 3 weeks (if on time) and hoping for same again! I read the bit about 'it's a boy if' and have symptoms for both boys and girls- so not scientifically accurate to say the least!! "just so long as it's healthy"- as they say!
Everyone told me I was having a girl when I was pregnant the first time - and I had a girl! Then the second time most people thought it would be a boy and, guess what, it was a boy. I know there's a 50-50 chance of getting it right but most of my friends just had a gut instinct. One friend said, during my second pregnancy, that because I hadn't lost my looks, I was having a boy - and she was right.