(Reuters Health) - First-time mothers who have an epidural are more likely to have a vaginal birth without forceps or other interventions if they’re lying down rather than upright during labor, a UK study suggests.
Researchers examined data on 3,093 women who had babies at 41 hospitals from 2010 to 2014. Women were randomly assigned to labor either lying down or upright.
Overall, 41 percent of the mothers who labored lying down had what’s known as a spontaneous vaginal birth, when the baby emerges without assistance from tools like forceps or a vacuum and a surgical cesarean delivery isn’t needed. That compares to 35 percent of the women who labored in an upright position.
“Lying down compared with being upright, increases a woman’s chances of having a spontaneous vaginal birth,” said study author Dr. Peter Brocklehurst of the University of Birmingham.
“This matters both to women and babies because avoiding instrumental births, whether with forceps or (vacuum extraction) or a cesarean section in the late stage of labor, avoids any of the traumas, both short term and long term, which follow from these interventions,” Brocklehurst said by email.
Roughly 30 percent of women in the UK choose spinal anesthesia known as an epidural during labor, and this method of pain relief is associated with longer labor and higher odds that tools or surgery will be required, researchers note in The BMJ.
Some previous research also suggests that the position women are in during the second stage of labor, when the cervix is fully dilated and it’s time to push, may independently influence their odds of having a spontaneous vaginal birth.
“We do not clearly understand how the lying down position increases the chances of a spontaneous vaginal birth,” Brocklehurst said.
It’s possible that when women are upright during the second stage of labor, swelling of tissues below the baby’s head in the birth canal might make it harder for women to push babies out, he said. It’s also possible that when women are lying down, contractions may be more productive at helping the baby emerge from the birth canal.
In the study, there was an almost 6 percent absolute increase in the chance of a spontaneous vaginal birth when women were lying down during labor.
Women were slightly more likely to have deliveries assisted by forceps or other instruments, a C-section delivery, or tearing or other injuries during delivery when they were upright, but the differences were too small to rule out the possibility that they were due to chance.
One limitation of the study is that more women stuck with their assigned labor position in the upright group than the lying down group, researchers note. This may be due in part to current guidelines in the UK that encourage women to be upright during labor, and it may mean the results underestimate the benefits of lying down.
The study findings are surprising because many clinicians believe that the added effects of gravity, along with being better able to tilt one’s pelvis, make delivery easier from an upright position, said Dr. Philip Hess, a researcher at Harvard Medical School and director of obstetric anesthesia at Beth Israel Deaconess Medical Center in Boston.
“This study goes against that belief,” Hess, who wasn’t involved in the study, said by email.
“This matters for patients because not all patients find squatting to be easy,” Hess added. “This is especially true if they are receiving denser epidural pain relief that decreases the strength in the woman’s legs.”
Based on the results, women should feel free to choose a labor position that makes the most sense in their individual situation, he said.
“Patients should be in a comfortable position for them during the second stage, and patients should not be forced to remain upright if it is challenging or uncomfortable,” Hess continued. “Being upright for some time can still be beneficial, but it’s ok to lie down for the delivery.”
SOURCE: bit.ly/2lHbBYO The BMJ, online October 18, 2017.