84% of patients receiving spinal manipulative therapy reported relief of back pain during pregnancy. There was significantly less likelihood of back labor when spinal manipulative therapy was administered during pregnancy.
Diakow PR, Gadsby TA, Gadsby JB, Gleddie JG, Leprich DJ, Scales AM. J Manipulative Physiol Ther. 1991 (Feb); 14 (2): 116-118