Does sex really works ?

Lucy
With my second child I gave birth to her at 38 weeks 5 days I remember the day before me and hubby had sex and it work! 
Does sex really put you in labor? I've been hearing it's true tomorrow I'll be 39 weeks with my 5th child I'm just scared he's never gonna be born all 4 of my other children's came on there own and this one just taking his time. My 4th was born 39 weeks 3 days I'm hoping he come this week because doctor wants to induced me and I don't want to be induced next week I want him come on his own.