Obviously I'm not qualified by personal experience, but I do know that labour is different for every woman. Some have short almost pain-free labours, some have longer more difficult labours. I also know that how ever much discomfort you feel, you will forget it when you hold your baby for the first time.
You need to discuss your worries with your midwife - she will advise you on techniques to ensure that you are in the best physical condition to deliver your baby, and how to relax as much as possible, including breathing techniques. which help during labour. She may also discuss an epidural injection - this is administered to your spine during labour, and you will feel no pain during birth.
It is perfectly natural to worry, regardless of how your baby was concieved, but do talk to your midwife, and do IGNORE experienced mums in ante-natal clinics who think it's clever to frighten first-timers with old wives' tales of agony and blood.
Giving birth is not easy, but it certainly is worth it!
Good luck!