did not become popular. Swedish professor Tage Malmstrom developed the ventouse, or Malmstrom extractor in the 1950s. Originally made with a metal cap, new materials such as plastics and siliconised rubber have improved the design so that it is now used more than forceps. Comparisons to other forms of assisted delivery Positive aspects An episiotomy may not be required. The mother still takes an active role in the birth. No special anesthesia is required. There is less potential for maternal trauma compared to forceps and caesarean section. Negative aspects The baby will be left with a temporary lump on its head, known as a chignon. There is a possibility of cephalohematoma formation, or subgaleal hemorrhage which can be life-threatening. There is a higher risk of failure to deliver the baby than with forceps, and an increased likelihood of perineal trauma. See also Odón device References Childbirth Medical equipment Obstetrical procedures