Moving induction to early morning could shorten labor by 6 hours

The best time to induce labor is early in the morning, research suggests. Morning inductions, in sync with our natural body clock, appear to shorten labor and reduce the need for C-sections.

“It’s a simple, free approach that could improve the experience for everyone – mother, baby and medical staff,” she says. Hanna Hoffmann at Michigan State University.

Around a third of births in the UK, US and Australia are now induced, meaning they are brought on by drugs or other artificial means, rather than waiting for them to start on their own. Induction is commonly recommended if the baby is overdue or has growth problems, as rapid delivery reduces the risk of stillbirth. Other reasons include the water breaking without going into labor, which can increase the risk of infection.

The problem is that induced labors are often more drawn out than those that occur spontaneously. “I had friends who were induced and went into labor for two days. I was blown away by how long and painful it was for them,” says Hoffmann.

This led Hoffmann – who studies circadian rhythms, natural oscillations in the activity of our tissues, driven by internal clocks – to wonder if there might be an optimal time of day for inducing labour. “We know that spontaneous labor follows circadian patterns because uterine contractions tend to peak in the late evening and we give birth primarily at night,” she says. This pattern may have evolved because there is less threat from predators at night.

To learn more, Hoffmann and her colleagues analyzed records of more than 3,000 induced labors performed at a Michigan hospital between 2019 and 2022. They found that the shortest labors were those induced between 3 a.m. and 9 a.m. For example, those induced at 5:00 a.m. lasted an average of 15 hours, while those induced at 11:00 p.m. lasted a staggering 6 hours longer, averaging about 21 hours. Shorter morning births were also less likely to result in emergency C-sections.

The reason for this early morning benefit may be that the receptors in the uterus respond better to the hormone oxytocin at this time. During spontaneous labor, oxytocin is responsible for stimulating uterine contractions. In inductions, a synthetic form of oxytocin is usually given to achieve the same effect. “When doctors induce labor with a big bolus of oxytocin, it can kick off the body’s built-in morning oxytocin party, giving contractions an extra excited push,” she says. Satchidananda Panda at the Salk Institute for Biological Studies in San Diego, California.

The researchers also found that people with a high body mass index or people who had given birth for the first time seemed to benefit the most from a morning induction. They now plan to investigate the underlying biological mechanisms.

While it may not be practical for hospitals to schedule all inductions between 3 a.m. and 9 a.m., they may consider prioritizing first-time mothers and those who are overweight or obese, Hoffmann says.

Importantly, the study found no health complications associated with induction early in the day. “There were no increased risks of NICU admission [neonatal intensive care unit] or other adverse outcomes,” says a team member René Cortese at the University of Kansas Medical Center. “This is another important message from the study: you mitigate one risk, but you don’t create another.”

The team now hopes to conduct a study to confirm that assigning pregnant women to induction early in the morning actually improves their delivery. “We need to do a proof of concept study to make sure we can replicate it [finding]” says Hoffmann.

Other chronotherapies—medical interventions that are timed to match circadian rhythms—are also being explored in oncology, cardiology, and psychiatry. For example, a recent study found that cancer treatment before 3 p.m. can help patients live longer.

topics:

• pregnancy and childbirth/
• circadian rhythm