There are some postural changes during pregnancy that are expected to occur with a normal pregnancy such as an increase in the lordosis (curvature of the lower back), increase in kyphosis (thoracic or mid back curve), difficulty breathing, forward head translation of the neck, pins and needles or numbing of the arms. Hormonal changes such as the release of relaxin can create ligament laxity further aggravating these changes. It is for this reason that Chiropractors in general have treated thousands of pregnant women throughout their normal pregnancy.
see also;
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.