RELAXIN: THE HORMONE FOR RELAXIN'
Ever wonder how the eff a human baby can come out of another human being? Relaxin is a big part of the answer.
WHAT IS IT?
Relaxin is a hormone produced by the ovaries—except for when you’re pregnant when it’s also made by the placenta and uterine lining. Its most obvious effect is right there in the name. That’s right, relaxin is for relaxin’ your muscles, ligaments, and joints.
During a regular menstrual cycle relaxin levels rise post ovulation, inhibiting contractions and helping to prepare the lining of the uterus for pregnancy. If pregnancy doesn’t occur, relaxin levels drop. And then the cycle starts all over again.
OMG IT DOES SO MUCH!
It helps you stay pregnant. When you ovulate during your menstrual cycle, your relaxin levels rise and help prepare your uterine lining for pregnancy and implantation. And it prevents against premature birth by inhibiting uterine contractions.
It keeps you and your baby healthy during pregnancy. Your relaxin levels are highest during the first trimester, when it works to relax your blood vessels, increasing blood flow to your placenta and kidneys. This is a really important job, because you and your fetus exchange nutrients and flush out waste through these organs.
It prepares your body to give birth. The pelvis is already pretty flexible—but relaxin gives your pelvis some extra stretch before and during labor. Plus, it is thought to help with the softening and opening of the cervix.
Relaxin obviously plays a major role in the menstrual cycle and pregnancy. But it’s also found in semen! Studies show that it may help sperm mobility.
WHEN STRAIGHT UP RELAXIN’ GETS TO BE TOO MUCH...
Higher relaxin levels during pregnancy can also have some not so relaxin’ effects. Softer and stretchier muscles and connective tissue can often mean aching hips, creaky or unstable joints, and (ugh) heartburn. Bumping into things? Feeling like your center of gravity is kinda off? That’s your relaxin’ at work. So be extra sure to administer some extra IRL relaxin’ and self-care (hello, pre-natal yoga) while you’re pregnant.
Goldsmith, Laura T., and Gerson Weiss. “Relaxin in Human Pregnancy.” Annals of the New York Academy of Sciences 1160 (2009): 10.1111/j.1749–6632.2008.03800.x. PMC. Web. 15 Jan. 2018. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3856209/
Dehghan, F et al. “The Effect of Relaxin on the Musculoskeletal System.” Scandinavian Journal of Medicine & Science in Sports 24.4 (2014): e220–e229. PMC. Web. 15 Jan. 2018. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4282454/
Ferlin A, Menegazzo M, Gianesello L, Selice R, Foresta C. “Effect of relaxin on human sperm functions.” Journal of Andrology, Vol. 33, No. 3, May/June 2012. https://www.ncbi.nlm.nih.gov/pubmed/21903973
Contributions by: Katie Okamoto, NYC