Causation in Birth Injury Cases

The final issue to be considered, although ultimately irrelevant due to the finding that emergency cerclage would not have been performed, was the cause of K.S.’s brain injury. The plaintiff had more success on this issue. There was some suggestion that infection was the cause of the brain injury. Moreau J. accepted the plaintiff’s expert’s opinion it was more probable than not that at the time of his birth, K.S. did not have an active infection that caused the damage to the white matter of his brain and other neurological injuries. She accepted that the progressive deterioration of the white matter of K.S.’s brain more probably occurred after his delivery and was the combined result of his extreme prematurity and the resuscitation procedures required in the first hours and days after delivery. The court also accepted that the Autism Spectrum Disorder was part of the prematurity related brain injury.

Medina (Litigation guardian of) v. Wong is another birth injury case that could not overcome the causation hurdle.⁸ The plaintiff, Cesar Medina was a five-year-old boy who sustained a catastrophic brain injury leading to cerebral palsy. As mentioned above, the fetal heart rate is one of the few available sources of information about fetal wellbeing during pregnancy, labour, and delivery. The issue in this case was whether the medical team was negligent in their interpretation of the fetal heart monitoring strips and whether the plaintiff ought to have been delivered much earlier than he was. Ultimately, Cesar Medina was delivered by emergency caesarean section in response to fetal heart rate abnormalities, but the plaintiff’s claim was that the delivery failed to occur in a timely manner and that earlier delivery would have avoided or minimized the plaintiff’s injuries.

Episodes of relative hypoxia are a regular part of childbirth. The mother’s contractions restrict blood supply and oxygen delivery to the fetus. When the contraction ends, the baby can catch its breath (so to speak) and withstand these interruptions in oxygenation.

When the periods of reduced oxygenation continue for longer, or the fetus has reduced capacity to recover from them, there are certain mechanisms the fetus can use to compensate for the reduced oxygenation and avoid injury. At some point, however, the level of hypoxia will overwhelm the infant’s ability to compensate and brain injury will occur on an exponentially increasing basis.

There are different types of brain injuries that occur under different conditions. If the hypoxia is mild but prolonged, particular parts of the infant brain will be injured. If the hypoxia is severe, different parts of the brain will be injured (and a baby can only survive a short time in these conditions). In Medina, the plaintiff’s theory of causation was that the fetus was compensating for an ongoing reduction in oxygenation until the last 14 minutes of the labour at which time his ability to compensate ended and brain injury set in. The plaintiff argued that he had sustained an acute profound (short but severe) hypoxic-ischemic injury minutes before delivery. The defendants’ theory of causation was that the infant had an infection that resulted in impaired placental blood flow and impaired oxygenation in the 12-36 hours prior to delivery. They denied the existence of a severe acute event that could have caused injury at the very end of the labour.

The court found that the plaintiff had not met the burden of proof. The existence of hypoxia alone is not enough to cause brain injury unless it overwhelms the fetus’s ability to compensate and the fetus is no longer able to cope with it. Abrioux J. held that the plaintiff had not established that the fetus was unable to compensate for the hypoxia in the minutes before birth. The court held that the plaintiffs had not established that an acute hypoxic-ischemic injury occurred. The plaintiff also argued that he was a “thin skull,” more susceptible to hypoxia due to intrapartum infection. Abrioux J. found that the inflammatory response from the infection was initiated 12-36 hours prior to birth and the fetus was still compensating at the time of delivery so he was unable to conclude that any damage flowing from that vulnerability would have been avoided if the plaintiff was delivered an hour earlier. Abrioux J. also indicated that the vulnerability from the earlier inflammatory response to the infection may have been the primary cause of the injury.