| p>What is relaxin? | | | | around the joint. Under the influence of relaxin the |
| Relaxin is a pregnancy hormone. It is produced in | | | | ligaments become more supple and pliable, |
| the early stages of pregnancy by the corpus luteum | | | | allowing increased movement which in turn reduces |
| (the shell of the egg left behind after ovulation), and | | | | joint stability. |
| then by the placenta from about the twelfth week | | | | Which joints are most at risk? The symphysis pubis |
| onwards. This hormone is evident in the body from as | | | | and sacroiliac joints of the pelvis are fibrous joints. |
| early as the second week of pregnancy, when it is | | | | Very little space separates the ends of the bones in a |
| produced in large amounts during the first trimester, | | | | fibrous joint, and in a non-pregnant state very limited |
| then reduces by 20% and continues to be produced | | | | movement, if any, takes place around the joint. |
| until the birth. | | | | Additionally, fibrous joints have no joint cavity and rely |
| Relaxin affects collagen fibres | | | | solely on ligaments for their stability. The resulting |
| Collagen is the main component of connective tissue | | | | increased range of movement of the symphysis pubis |
| found in cartilage, tendons and ligaments. The | | | | and sacroiliac joints, together with the progressive |
| stability of all joints is maintained by ligaments which | | | | pressure exerted by the growing baby, places |
| are made up of these dense, fibrous strands of | | | | these joints in an extremely vulnerable position. |
| connective tissue. During pregnancy relaxin increases | | | | What about the abdominal and pelvic floor muscles? |
| the water content of collagen fibres, increasing their | | | | Collagen is also found in the connective tissue of the |
| size and elasticity. | | | | abdominal and pelvic floor muscles. This is necessary |
| What effect does this have on the joints? Ligaments | | | | for the abdominal muscles to stretch and allow the |
| are normally inelastic, a quality necessary to maintain | | | | uterus to grow out of the abdomen, and for the pelvic |
| joint stability and prevent unnecessary movement | | | | floor muscles to stretch to deliver the baby. |