Both procedures are effective and safe. The decision will often be based on the baby’s position, and how she or he may need to be turned around. Your obstetrician will definitely choose the most suitable instrument for your baby, you and the entire situation.
However, if you are under 34 weeks pregnant the ventouse cannot be used as baby’s head is too soft. In general, the forceps are considered to be more successful for deliveries, however, a ventouse carries a smaller risk of vaginal tearing.