References:

http://welladjusted.co/pregnancy-faq/#q4

(1) Fast A. Low Back Pain in Pregnancy. Spine. 1987;12(4):368-371., Berg G. Low Back Pain During Pregnancy. Am J Obstet Gyn. 1988;71:71-75.

(2) Diakow P. Gatsby T. et al. Back Pain During Pregnancy and Labour. JMPT. 1991;14:116-118. 

(3) Penna M. Pregnancy and Chiropractic Care. ACA. J. Chiro. 1989;26:31-33. 

(4) Henderson I MD. American Medical Association records released in 1987 during trial in U.S. District Court Northern Illinois Eastern Division, No. 76C 3777. May, 1987. 

(5) Fallon J DC. The Effect of Chiropractic Treatment on Pregnancy and Labour: A Comprehensive Study. Proceedings of the World Federation of Chiropractic, 1991:24-31., Fallon J DC. Chiropractic and Pregnancy, a partnership of the future. ICA Review Nov/Dec 1990. (pg. 39-42)