The arguments for and against
If you need an assisted delivery, the choice of how your baby will be born, and the type of method(s) used, will depend on the position of the baby, how far the baby's head has come down the vaginal canal, if you are fully dilated, and the experience and preferences of your caregiver.
In recent years, there has been a swing away from the use of forceps, and a move towards the use of the ventouse. In Europe, the ventouse would be used more frequently than in the United States. In Australia, the use of either will depend on the hospital and the individual caregiver. Some hospitals and caregivers will tend to use forceps more often, and some ventouse.
The arguments for and against
Both forceps and ventouse have their 'pros and cons' and there are no guarantees that either (or both) will be successful. The choice between them is controversial, and different caregivers will have different points of view about the most appropriate method that should be used in different circumstances.
Likelihood of success
Pain relief
Episiotomy
Fully dilated cervix
Injury to the mother
Injury to the baby
Mother's attitude
Likelihood of success. If the baby's head is low in the pelvis, in an anterior position and well flexed (chin on chest), then either method will probably be successful. If the baby's head is high, posterior and deflexed, then forceps, or a metal cup ventouse, will probably be more successful, but it may depend on the type of equipment your caregiver is more familiar with using. In Australia, forceps would be more commonly used in this situation.
If the ventouse is tried first, and does not succeed, then forceps can be tried. (If forceps are tried first, your caregiver is unlikely to succeed with a ventouse). This 'changing of methods' has shown to increase the risk of injury to the baby. If the forceps are tried 1st or 2nd and they are still not successful then a Caesarean will be needed.