What is Relaxin?


When a woman is ready to deliver a baby, a complex series of changes take place in the body to prepare for labor and birth. Most of those changes are triggered by hormones, including relaxin.

Relaxin is a hormone secreted in the ovary by the corpus luteum. When a woman is pregnant, the placenta will also release the hormone, as will the uterine lining. Men also have relaxin, which comes from the prostate gland and is found in semen, but in men it does not circulate in the blood.

What does relaxin do?

Relaxin is crucial to the female reproductive process. Relaxin levels increase after ovulation during the second half of a woman's menstrual cycle, where it is believed to relax the wall of the uterus and prepare it for pregnancy. If a woman does not conceive, levels drop until the next cycle.

If the woman does conceive, relaxin levels continue to grow through the first trimester, aiding in implantation and placenta growth. This hormone also stops contractions as the tiny baby grows to prevent early delivery. At the end of pregnancy, when labor begins, relaxin helps to relax the ligaments in the pelvis to allow it to stretch as the baby leaves the mother's body.

Other effects of relaxin have surfaced in recent studies, as new relaxin peptides have been discovered. Relaxin has been proven to lessen tissue fibrosis in many organs, and can also promote wound healing. Relaxin has also been found to reduce blood pressure by relaxing the blood vessels. This has led to more study into benefits of relaxin peptide treatment for certain diseases.

Problems Associated with Relaxin

Few studies have considered the side effects of relaxin either in high or low levels. Some have suggested that high relaxin levels can cause a pregnant woman's membranes to rupture, leading to premature birth in pregnant women, but this has not yet been proven. Low relaxin levels may cause scleroderma — a thickening and hardening of the skin — but again, this needs to be studied further.

Questions for your doctor

If you have questions about relaxin levels in the body, discuss them with an endocrinologist. Some questions may include:

  • Do I need to be concerned with relaxin levels?
  • Can relaxin levels impact my pregnancy?
  • Could relaxin be a treatment option for my condition?

While relaxin levels have not been linked to any specific diseases, treatment with relaxin is starting to be offered as a solution for some diseases. If you do not have an endocrinologist, find one today.

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