Researchers have long attempted to pinpoint if something other than the health of the mother or her baby leads to complications during delivery. Past studies have considered the timing or type of delivery or whether a patient was under the care of a senior or junior doctor, but findings were inconclusive. For the first time, a new study shows that one key variable leads to a higher rate of negative outcomes: doctor fatigue.
A new study from McCombs has found that the number of hours an obstetrician works before undertaking unscheduled deliveries significantly influences the risk of adverse outcomes for both the mother and unborn baby.
Statistician and Associate Professor James Scott, together with co-authors from Cambridge University and the LBJ School of Public Affairs at UT, wondered if the total number of hours worked during a shift may be a more important predictor of dangerous complications than whether the delivery occurred during the weekend or in the middle of the night, as previous researchers had suggested.
Scott looked at nearly 25,000 unscheduled deliveries in the United Kingdom from January 2008 to October 2013. The obstetricians, all from the same labor and delivery ward, consistently worked 12-hour shifts.
They found no significant differences in the rates of common adverse outcomes between day and night shifts, weekday versus weekend shifts, vaginal or c-section deliveries, or whether the delivery was overseen by a junior or more senior doctor.
Instead, they found that two specific complications — maternal hemorrhaging and fetal acidosis, or low blood oxygen levels in an unborn baby — increased substantially when a physician entered the ninth hour of a 12-hour shift.
“There are all sorts of studies about the timing of deliveries,” says Scott, “but what no one had looked at before is whether there is some kind of proxy for how fatigued doctors are. We find there’s a peak eight to 10 hours after the beginning of a shift when, relative to baseline, the risk of maternal blood loss exceeding 1.5 liters increases by 30 percent, and arterial pH, a marker for infant distress, is at increased risk of falling below 7.1.” Normal pH is between 7.3 and 7.4.
The researchers hypothesized that fatigue led doctors to miss small fetal distress signals. Scott says those signals likely would have been caught if doctors were a bit fresher and sharper.
Surprisingly, the researchers also found that maternal blood loss and low blood oxygen levels actually dropped in the last two hours of doctors’ shifts, when they’d likely be the most fatigued. After consulting with the obstetricians from the five-year study, they concluded that the risk level probably drops because doctors defer more complicated and high-risk, but non-emergent, cases for the next shift.
“We can’t say that if you change the staffing patterns in hospitals that all of a sudden, everything would be better, but I do think these kinds of studies have a role to play,” says Scott. “We should try to analyze not just clinical factors but also factors that are more operations-driven, and scheduling and staffing are a big part of that.”
He adds that one part of clinical practice that hasn’t been researched extensively is how staffing decisions percolate down and affect patient outcomes. The goal for these kinds of findings, he emphasizes, is to help hospital administrators think more systematically about how staffing processes can minimize avoidable but serious complications.
The Influence of Hours Worked Prior to Delivery on Maternal and Neonatal Outcomes: A Retrospective Cohort Study appears in the American Journal of Obstetrics and Gynecology. It was co-authored by Catherine Aiken and Jeremy Brockelsby from the University of Cambridge and Abigail Aiken at the LBJ School of Public Affairs at The University of Texas at Austin.