- Outcomes are more likely to occur if the midwife is in the ninth hour of their shift
- This is when risk of maternal blood loss and low blood oxygen levels are highest
- Scientists say this is because fatigue causes obstetricians to miss small signals
- Risk was lower in the final part of a 12-hour shift – when they should be most tired
Calling all pregnant women – the most dangerous time that you can give birth has been discovered. Deadly delivery outcomes are more likely to occur if the midwife in charge is in the ninth hour of their shift, scientists claim. This is when the risk of maternal blood loss and low blood oxygen levels in the womb are highest, a study found.
Researchers say this is because fatigue causes obstetricians to miss small distress signals they would usually spot. However, the University of Texas at Austin, study discovered the risk was lower in the final part of a 12-hour shift – when they should be most tired. Experts said that this may be because they pass more complicated cases onto fresh colleagues who have just started their day. Lead author Dr James Scott said: ‘There are all sorts of studies about the timing of deliveries, but what nobody had looked at before is whether there is there some kind of proxy for how fatigued the doctors are.’
He said that in the ninth hour, the risk of maternal blood loss exceeding 1.5 litres – around three pints – increases by 30 per cent. While arterial pH, a known marker for infant distress, is at increased risk of falling below 7.1 during this time. It should be between 7.3 and 7.4 for a healthy baby. For the study, the researchers assessed 24,506 unscheduled deliveries in the United Kingdom between 2008 and 2013. All obstetricians monitored worker on the same labour and delivery ward and mainly worked 12-hour shifts over the five years.
The findings showed no significant differences in the rates of common adverse outcomes between day versus night deliveries. Similarly, no pattern was found for weekday versus weekend deliveries, vaginal or Caesarean, or even whether a doctor was junior or more senior. The study was published in the American Journal of Obstetrics and Gynecology.