At the outset, Dr Weston said he found the circumstances weren't clear; there were discrepancies within the different reports. Most perplexing was that a baby who was reported as well at birth should be in a state of collapse 15 minutes later and dead two hours later.
It was extremely rare and equally perplexing that the reason for the death had not been found.
Looking at Ms Brider's pregnancy history or her labour, Dr Weston said there was nothing to indicate the birth would be a problem.
Tane's family contend he had trouble breathing from the outset and appeared to be blue and floppy. However, Ms Baker recorded the baby's Apgar score - a measure of a healthiness after birth - as a nine out of 10 a minute after he was born, and it remained nine when he was rescored five minutes later.
Fifteen minutes later, however, Tane had collapsed and was rescored as a four. In the intervening time, Ms Baker had left the room to attend to the placenta and get an ice pack for Ms Brider. How long she was gone was also under dispute by Tane's family.
Dr Weston said that, assuming the Apgar scores were correct, he could not imagine how a baby could be in such an extreme state after being recorded as healthy 10 minutes earlier.
He could also not reconcile how Ms Baker's notes showed a five-minute gap between the time she found Tane had collapsed, and the time she began resuscitation. He called the gap "uncomfortably long" and said he could not attribute the time delay to differing clocks when she had put the gap in her own notes.
There were imperfections with the resuscitation done by hospital staff, but the necessary expertise was not always immediately available at a small hospital. That one doctor chose not to intubate (place a tube into the windpipe to maintain an open airway) was unfortunate. He was unable to say if it had made a difference, but it was an opportunity lost.
Dr Weston put forward theories on what may have happened to Tane: unintentional smothering, narcotics-related due to the drugs Ms Brider was given at a late stage of labour, birth asphyxia or in-born malformation.
Unintentional smothering was unlikely, and he felt the levels of narcotics in Ms Brider's body shouldn't have affected Tane, but he couldn't be sure.
He couldn't be confident of asphyxia when the electrocardiogram and Apgar scores were normal, and an in-born malformation was eliminated at the post-mortem examination.
That examination did find Tane had a small brain haemorrhage at birth, and infection in his lungs but it was hard to tell what impact the haemorrhage would have had. If he had been having difficulties adjusting to being outside the womb his Apgar's would have been lower, Dr Weston said.
The infection in his lungs wasn't significant enough to have caused death.
He conceded under cross-examination that it seemed possible the Apgar scores were wrong, and if they were, that made the possible causes of Tane's death more likely.
Cheryl Baker was cross-examined by Ms Brider's lawyer, John Rowan, QC, and said she had been out of the room less then five minutes and immediately attended to Tane when she found him collapsed. The time delay she recorded was due to a difference in the times on the clocks in rooms at the hospital.
If she had considered Tane was going to "go flat" she would never have left the room, she said. She had done so at the insistence of Ms Brider's mother, who wanted to take the placenta and leave.
Asked why she didn't call for another midwife to go to the room while she was out, she said the other midwife there had already told her she would be in another ward, and wouldn't be in the office if the bell rang.
"At the time it might have been a bad decision ... In retrospect, yes it was a bad decision."
Mr Rowan said Tane's family gave evidence that he was in distress before she left, but Ms Baker said they all gave differing versions, 12 months after it happened.
It was understandable that they were distressed, looking for a reason and for someone to blame.
The inquest is expected to conclude today.
