In a discovery that could shift labor and delivery practices around the world, researchers at Michigan State University 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, published in Molecular Metabolism, combined laboratory research in mice and human cells with a retrospective 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, associate professor of animal science at MSU and lead author of the study.