Risk factors include prolonged labour, difficult instrumental delivery and paramedian episiotomy.

The usual causes of a cephalohematoma are a prolonged second stage of labor or instrumental delivery, particularly ventouse.

Risk factors for fetal birth injury include fetal macrosomia (big baby), maternal obesity, the need for instrumental delivery, and an inexperienced attendant.

Risks to the fetus increase slightly after 42 weeks' gestation but women having labour induced are more likely to have instrumental deliveries or babies with low Apgar scores.

Macrosomia in turn increases the risk of instrumental deliveries (e.g. forceps, ventouse and caesarean section) or problems during vaginal delivery (such as shoulder dystocia).

In contrast, labour monitored by CTG is slightly more likely to result in instrumental delivery (forceps or vacuum extraction) or Cesarean section.

Traditionally the diagnosis of "fetal distress" led the obstetrician to recommend rapid delivery by instrumental delivery or by caesarean section if vaginal delivery is not advised.

Forceps Ventouse, sometimes known as vacuum extraction Caesarean section Using forceps or a ventouse is sometimes known as 'instrumental delivery'.

Induced labour is longer and is associated with more instrumental deliveries, an increased risk of postpartum haemorrhage, and perhaps most importantly, a higher incidence of low Apgar scores than spontaneous labour.

In Europe and North America the foundation of the metropolitan maternity hospitals, together with instrumental deliveries and the practice of attending necropsies, led to epidemics of streptococcal puerperal fever, resulting in maternal mortality rates up to 10%.

It is not surprising that the women who had epidural analgesia had significantly longer labours, a greater requirement for oxytocin, and a higher rate of instrumental delivery as such factors increase the need for epidural analgesia and therefore cannot be assumed to result from it.