Physiological Changes in Pregnancy

Anatomy of the female

The pelvic girdle protects and supports the pelvic contents, provides muscle attachment and facilitates the transfer of weight from trunk to legs in standing, and to the ischial tuberosities in sitting.The joints are supported by some of the strongest ligaments in the body which become more lax during pregnancy leading to increased joint mobility and less efficient load transfer through the pelvis. The pelvic outlet at the base of the pelvis is narrower in transverse diameter when compared with the pelvic inlet; it comprises the pubic arch, ischial spines, sacrotuberous ligaments and coccyx.

Four pairs of abdominal muscles combine to form the anterior and lateral abdominal wall, and may be termed the abdominal corset. Transversus abdominis (TrA), whose fibres run transversely, lies deep to the internal abdominal oblique (IO) and external abdominal

oblique (EO), with the rectus abdominis (RA) central, anterior and superficial (Figure 27.2). IO, EO and TrA insert into an aponeurosis joining in the midline at the linea alba. The deep abdominal muscles, together with the

pelvic floor muscles, multifidus and diaphragm, can be considered as a complete unit and may be termed the lumbopelvic cylinder. This provides support for the abdominal contents and maintains intra­abdominal pressure