Well, i know its all just anecdotal evidence for me.
But i did read about cells developing and splitting. Apparently they divide at a slower pace in males compared to females. Which is why if you ever read about the risk of ultrasound, something that will probably pop up in your reading will be how the brain cells of boys take longer to divide than in girls, and so if there is a risk with ultrasound, boys tend to have more the effects than girls. (because the ultrasonic waves slow down the cell division process). Anyways, thats just the scientific evidence that boys do take longer to develop...which can be seen across the board once they are born, even into adolscence and adulthood, we know that girls, on average, develop 2 years faster than boys....thus, i think there really could be something to being mroe liekly to go overdue with a boy than a girl
NOTE* boys can still come early[and they do] and girls can still come late [and they do] but in general there does seem to be a trend.
Thus far, i can personally attest to this-Isaiah was almost 2 weeks overdue. But yes, with my child birth students and with my doula clients, i do see the trend...i mean obviously it can (and does) go differently, but from my personal experience, the trend is def there.
! I have been in so much pain today, and the pain made me nauseous... and to top it off in the height of the pain I get a call from DS1's teacher saying about him being disrespectful to her and being REALLY bad in school today!! UGHHHHH..... after that phone call I just cried for a little bit.
if you come up with any tricks, PLSPLSPLS let me know lol
Congrats 
hth!
I am excited for you 