Posture Affects Pelvic Dimensions

If you've ever wondered whether positioning affects pelvic dimensions or whether this is an "old midwives" tale, wonder no more. A 2014 study found that it did. Investigators used obstetric magnetic-resonance imaging pelvimetry to measure pelvic dimensions in pregnant women and nonpregnant women in a kneeling squat (the machine would not allow measurements in a more upright position) vs. lying on their backs. The kneeling squat expanded the pelvis by a significant amount. What is more, the difference was more pronounced in pregnant women. Interestingly, the investigators were trying to determine optimal positioning for vaginal breech delivery. They note that current guidelines for vaginal breech assume that the woman is on her back and suggest that more upright postures might facilitate spontaneous birth of the aftercoming head, which could reduce maternal and newborn morbidity. - Henci Goer