Check out this study:
https://community.babycenter.com/post/a28809819/gender_prediction_based_on_which_side_of_the_uterus
"Dramatic differences were detected in chorionic villi / placental location according to gender. 97.2% of the male fetuses had a chorionic villi/placenta location on the right side of the uterus whereas, 2.4% had a chorionic villi/placenta location to the left of the uterus. On the other hand 97.5% of female fetuses had a chorionic villi/placenta location to the left of the uterus whereas, 2.7% had their chorionic villi/placenta location to the right side of the uterus"
I have heard the accuracy is near 100% on this method! According to their methods, you have a 98% chance of the baby being a girl!! Unless this was a trans-vaginal scan...in which case the the u/s is a mirror image (MEANING BOY!) So was it trans-vag or abdominal? I really am curious to see if this works!
Given that that "study" was an error-riddled post written by an ultrasound instructor on an OBGYN website and not an article published in a peer-reviewed journal or evaluated by any follow-up studies, I would take the results with a hefty grain of salt.
I should also point out that in the discussion, the author tries to claim that the site of implantation is not just an indicator of sex, but that it's actually what
determines sex. His argument is that differences in temperature "influence the sex chromosome" to be male or female. Anyone who has taken a high school biology class can see how ludicrous this claim is - human sex is determined at conception.