The Effects of Chiropractic on Pregnancy and Labour; A Comprehensive Study. FALLON J. Proceedings of the world chiropractic congress. 1991; 24-31

The hormonal changes that occur during pregnancy can change the shape of the spinal curves and overall posture which can affect organ systems.

In this study Dr Fallon describes her work with 65 women who received Chiropractic care from at least the tenth week of pregnancy through labour and delivery. These women experienced mean labour times significantly reduced compared to controls.

Women who were primagravidae (first pregnancy) who received chiropractic care averaged 24% shorter labour times than average for primagravidae women.

Women who were multiparous (had had at least one child prior) averaged 39% shorter labour times versus the controls

Back pain during pregnancy and labor. Diakow, PRP, Gadsby, TA, Gadsby JB et al.J
Manipulative Physiol Ther Vol. 14, No. 2 Feb. 1991.

From the abstract:
An interview of 170 consecutive female patients: of the 170 pregnancies with reported back pain, 72% also reported back labor...The treated group experienced less pain during labor.
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.