Experts pinpoint the worst time of day to give birth

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I was always worried that I'd give birth in the early hours of the morning. I figured everyone would be tired, there would be only skeleton staff, and things could go wrong.

So I was relieved that I ended up being induced for two of my three births – giving birth at what my doctor called "Mediterranean lunchtime": mid-afternoon. So civilised.

For years, researchers have been studying thousands of births trying to discover what the best and worst days and times are to give birth. But the latest research shows that perhaps they've been asking the wrong questions.

It turns out it's not the calendar or the clock we should be looking at, it's the timesheet of the doctor delivering the baby.

"There are all sorts of studies about the timing of deliveries, but what nobody had looked at before is whether there is some kind of proxy for how fatigued the doctors are," Dr James Scott, associate professor of statistics at the University of Texas, explained in a new paper published in the American Journal of Obstetrics and Gynecology.

Dr Scott and his team of researchers studied unscheduled deliveries in the UK, assessing 24,506 births from 2008 to 2013. All the doctors in the study worked 12-hour shifts.

What the study showed was that there was no significant difference in the births according to the time they occurred, nor the experience or rank of the doctors involved. Where they did discover a massive difference was in how many hours the doctors had been working when the birth occurred.

Dr Scott says that when a doctor reached the ninth hour of their shift, that's when mothers suffered the worst blood loss and the baby suffered from low oxygen level increase. That means tired doctors were missing small markers that are early indicators of trouble.

"We find that 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 litres increases by 30 per cent and arterial pH, a marker for infant distress, is at increased risk of falling below 7.1," says Dr Scott. (Arterial pH of 7.3-7.4 is considered normal.)

This increased risk then disappeared again by hours 11 and 12 because doctors finishing their shifts are more likely to hand a complex birth over to someone just beginning their shift.

So the good news is that it doesn't matter what time or day you give birth. But what does matter is how fatigued your doctor is when the time comes. If you have any concerns, ask in advance how your hospital manages its rosters, or speak to the doctor on duty.