Progesterone, ovulation and birth control?

[scilearner]

Hello everyone,

 

I'm slightly confused here. After ovulation, progesterone increases markedly. Now progesterone is also used as a contraceptive for creating a hostile environment for fertilisation and not allowing sperm to enter. So after ovulation how does fertilisation occur normally, if progesterone increases right after that. I see that it takes like 5 days for progesterone to peak. So does fertilisation have to occur before progesterone increases a lot. Also after fertilisation, doesn't the effects of progesterone cause any problems to the fertilized egg. Thanks