A highly durable network of ligaments surrounds these joints giving them tremendous strength. The pubic symphysis has a  fibrocartilage joint which may contain a fluid filled cavity and is avascular; it is supported by the superior and arcuate ligaments. The sacroiliac joints are synovial, but their movement is restricted throughout life and they are progressively obliterated by adhesions. The nature of the bony pelvic ring with its three joints determines that no one joint can move independently of the other two. Relaxin hormone
Relaxin is a hormone produced mainly by the corpus luteum of the ovary and breast, in both pregnant and non-pregnant females. During pregnancy it is also produced by the placenta, chorion, and decidua. The body produces relaxin during menstruation that rises to a peak within approximately 14 days of ovulation and then declines. In pregnant cycles, rather than subsiding, relaxin secretion continues to rise during the first trimester and then again in the final weeks. During pregnancy relaxin has a diverse range of effects, including the production and remodelling of collagen thus increasing the elasticity of muscles, tendons, ligaments and tissues of the birth canal in view of delivery. Although relaxins main cellular action in pregnancy is to remodel collagen by biosynthesis (thus facilitating the changes of connective tissue) it does not seem to generate musculoskeletal problems. European Research has determined that relaxin levels are not a predictor of PGP during pregnancy. Gait changes
The pregnant woman has a different pattern of "gait".
Saccharopinuria (an excess of saccharopine in the urine), also called saccharopinemia, saccharopine dehydrogenase deficiency or alpha-aminoadipic semialdehyde synthase deficiency, is a variant form of hyperlysinemia. It is caused by a partial deficiency of the enzyme saccharopine dehydrogenase, which plays a secondary role in the lysine metabolic pathway. Inheritance is thought to be autosomal recessive, but this cannot be established as individuals affected by saccharopinuria typically have only a 40% reduction in functional enzyme. See also
Hyperlysinemia

References
External links
Saccharopinuria; Alpha-aminoadipic semialdehyde synthase deficiency at NIHs Office of Rare Diseases