The study is one of many findings about the biology of pregnancy to come out of Stanford’s Prematurity Research Center.Īlthough women deliver around 40 weeks of pregnancy on average, going into labor at anywhere from 37 to 42 weeks’ gestational age is considered normal. “The other part of the equation is the mother.” But there is a disconnect between this timing and when labor starts, because whether the baby is ready is only one factor in the onset of labor,” said Brice Gaudilliere, MD, PhD, the study’s senior author and associate professor of anesthesiology, perioperative and pain medicine. “Clinicians are good at estimating gestational age, which measures the development of the fetus. “It’s not a single switch there’s this preparation that the body has to go through.” Getting mother and baby ready for birthĬlinicians currently estimate a woman’s due date by counting 40 weeks from the first day of her last menstrual period and taking into account ultrasound data about the baby’s size. “The mom’s body and physiology start to change about three weeks before the actual onset of labor,” said co-author Virginia Winn, MD, PhD, associate professor of obstetrics and gynecology at Stanford.

The change to pre-labor maternal biology is characterized by changes in levels of steroid hormones, factors that control blood vessel growth and blood coagulation, and immune regulatory signals, the study found. The shift from ongoing pregnancy to the pre-labor phase was detected both in women who had full-term pregnancies and in women who delivered prematurely. This prediction is independent from the duration of pregnancy.” “We’ve identified a novel way to use the maternal blood to predict when a mother will go into labor. “We found a transition from ‘progressing pregnancy’ to a ‘pre-labor’ phase that happens two to four weeks before the mom goes into labor,” said Ina Stelzer, PhD, the study’s lead author and a postdoctoral scholar in anesthesiology, perioperative and pain medicine at Stanford. The method narrows the predicted delivery time to a two-week window, and the researchers expect it will become even more precise as the technique is refined. The researchers expect their findings to yield a test within the next two to three years that doctors can use to predict labor onset in healthy pregnancies. Current estimates are imprecise, with anything in a five-week window - from three weeks before to two weeks after the due date - considered a normal delivery time. The findings lay the groundwork for a clinical blood test that could tell women with healthy, full-term pregnancies how close they are to delivery. The study, which was published online May 5 in Science Translational Medicine, sheds light on how labor begins, a biological process that until now has been a mystery. For the first time, researchers have found a way to predict when a pregnant woman will go into labor by analyzing immune and other biological signals in a blood sample, according to a study from the Stanford University School of Medicine.

Mood changes before labor