Babies are most likely to be born at this time, new study

Photo: Shutterstock
Photo: Shutterstock 

If you went into labour spontaneously and welcomed your baby in the early hours of the morning, then you're not alone.

A new large scale study has found that mums who delivered without any intervention were most likely to give birth between 1am and 7am with a peak at 4am. And the reason, the researchers explain, most likely has its basis in evolution.

"Long term experience and research from other areas has shown that human births without obstetric intervention are most likely to occur at night or in the early hours of the morning," said lead author Dr Peter Martin of the findings. 

"This may be part of our evolutionary heritage. Our ancestors lived in groups that were active and dispersed during the day and came together to rest at night. So a night-time labour and birth probably afforded the mother and newborn baby some protection."

As part of the study, published in the journal PLOS One, Dr Martin and his team analysed data from over five million singleton babies born in the UK between 2005 and 2014. Overall, they found:

  • 28.5 per cent of births occurred between "usual working hours" of 9.00am and 4.59pm on weekdays
  • 71.5 per cent of births occurred outside these hours at weekends, on public holidays or between 5.00pm and 8:59am on non-holiday week days.

That's a lot of babies born after hours!

The team also found that bubs prefer not to make their appearance on weekends or on important dates. According to the data, the average number of spontaneous births were around one per cent lower on Saturdays, two per cent lower on Sundays and public holidays and seven per cent lower on Christmas and Boxing Day.

Data released from the Australian Bureau of Statistics last year, revealed that December 25 and December 26 were also in the top five least common birthdays over the past ten years.

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Mums who were induced, regardless of their mode of birth, were most likely to give birth at around midnight on Tuesdays to Saturdays and on days before a public holiday period. 

When it came to elective or pre-planned caesarean sections, which accounted for nine per cent of births, women most commonly welcomed their bubs between the very civilised hours of 9am and 11:59am. "Very few occur between 17:00 and 7:00 on weekday evenings and nights, and even fewer at any time at weekends and on holidays," the authors note.

While this finding may not be a surprise, the data on emergency caesarean sections was. "Emergency caesareans would be expected in response to an urgent clinical need and thus be independent of the day of the week," the team wrote.

"Yet we found that numbers of emergency caesareans without any record of prior onset of labour were considerably lower on Sundays and holidays than on weekdays, and that their numbers were highest on days immediately preceding weekends and public holidays."

Dr Martin said it's also not "straightforward to understand why numbers of spontaneous births, without any obstetric intervention, were lower on Christmas Day and Boxing Day than on other days of the year.

"Selective obstetric intervention in preceding days could be an explanation but more research would be needed to investigate this," he noted.

While it's important to reiterate that the study is based on UK data, the authors believe the results have the potential to inform best practice in maternity care. 

"The timing of births varies by onset of labour and mode of birth and these patterns have implications for midwifery and medical staffing. Further research is needed to understand the processes behind these findings."

Elizabeth Duff, senior policy advisor at NCT, the UK's largest parenting charity, agrees, particularly when it comes to induced births. "This study tells us parents aren't bothered about the timing of the birth as long as it results in healthy mums and babies. So it's worrying that induction appears to be timed so that the babies are most frequently born around midnight, when senior staff are less widely available to assist if complications arise."

Last year, a US study published in the American Journal of Obstetrics and Gynecology found that rather than time or day of birth, the most important factor for a safe delivery was how many hours the doctor had been on shift. "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 seven," said lead author Dr James Scott at the time.