Circadian rhythm discovery may transform what time of day doctors induce labor (8 AM - Noon is best)

Medical Xpress / Michigan State University / Molecular Metabolism ^ | Nov. 14, 2025 | Kim Ward / Thu Van-Quynh Duong et al

[ConservativeMind]

In a discovery that could shift labor and delivery practices around the world, researchers have found that the effectiveness of oxytocin—a common medication used to induce or speed up labor—depends on the time of day it's administered, especially for patients with gestational diabetes.

The study combined laboratory research in mice and human cells with a review of more than 2,300 pregnancies.

The results were striking. Women whose labors were induced in the early morning to around noon experienced significantly shorter labor durations than those induced around midnight. For patients with gestational diabetes, the timing difference amounted to as much as seven hours.

"Our findings suggest timing isn't just about scheduling—it can affect how well a patient's uterus responds to labor-inducing medication," said Hanne Hoffmann.

At the center of the discovery is BMAL1, a key circadian rhythm gene that helps control the body's biological 24-hour clock. In mice, the researchers showed that BMAL1 helps regulate the oxytocin receptor in the uterus, which is the same receptor that synthetic oxytocin targets to trigger contractions. When the gene was turned off or suppressed, either genetically or through a mouse model of gestational diabetes, oxytocin was significantly less effective at inducing contractions.

In human cell experiments, MSU scientists observed a circadian rhythm of contraction responses to oxytocin confirming what had previously only been speculated.

The team also analyzed labor and delivery records, focusing on more than 2,300 patients who were at least 39 weeks pregnant. Labor duration was compared across different time windows of the day and between patients with and without gestational diabetes.

The shortest labors occurred when induction started between 8 a.m. and noon and the longest when induction began between midnight and 4 a.m. This effect was especially dramatic in patients with gestational diabetes, suggesting reduced oxytocin sensitivity during nighttime hours.

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TOPICS: Health/Medicine
KEYWORDS:

[ConservativeMind]

Have your pregnancy induced with oxytocin between 8 AM and noon, if needed.

[ConservativeMind]

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[Harmless Teddy Bear]

Most babies arrive at night.

And during a storm.

At least to hear my mother tell it.

I checked and I did arrive at 1:27 in the morning. No storm though. That might have been one of the other one.

[cpdiii]

Me = hospital clinical pharmacist retired.

The orders for oxytoxin came down mostly early in the morning shift to induce labor, 0800 to about 1000. This was a convenience for the Docs. If the article is correct it was oddly the right time for those orders.

[FamiliarFace]

Do they no longer use pitocin to induce labor?

[ConservativeMind]

Very interesting!

[Sacajaweau]

My son arrived at 11:50 PM....10 minutes before midnight. We had to pay for the whole day for him. I was livid. It should have been prorated OR...it should have been paid by the doctor who induced labor. Cost was $20 in 1967.