What is Relaxin: Hips Don't LiePregnancy
I debated about the alternative titles, “Why I'm Suddenly a Klutz During Pregnancy” or “How a Baby is Actually Going to Fit Through There” to describe a little-known hormone, called relaxin, which is responsible for a lot of the changes that happen during pregnancy and labour. So what exactly is relaxin? Over the course of pregnancy, your body will produce a lot of hormones in order to sustain both your needs and your baby’s needs. One of these is the protein-based relaxin, a softening and relaxing hormone, which is usually produced by your ovaries. During pregnancy, the small amount of relaxin produced isn't quite enough to meet the demand, so your placenta and even your uterine lining begin secreting relaxin—ten times more than normal, in fact!
Effects of Relaxin During Pregnancy
Because of such high levels of relaxin in your system during pregnancy, it's no surprise that you will notice a few interesting changes. Many pregnant women have reported achy joints, feeling off-balance, and becoming a little accident-prone—relaxin may be to blame. This hormone makes your ligaments and joints more elastic and pliable, reducing their stability.
Stretch and flexibility is a must during pregnancy, so relaxin is actually a really good thing! Your uterus and skin must stretch as your baby grows; your breasts gently expand to prepare for the volume of breastmilk, and your blood vessels relax to accommodate your 50% increase in blood volume. Your body must work hard to circulate the blood to two people, as well as process waste products for two. Relaxin helps you adjust to this process by relaxing your blood vessels to increase blood flow, which carries nutrients into the placenta and waste out. Relaxin also promotes the ligaments of the pelvis to relax, so when the time comes, you can push your baby through!
The Effects of Relaxin During Labour
Relaxin doesn't just prepare your body for pregnancy: it sees you all the way through to the end. During labour, your cervix must become soft, stretchy, and eventually pliant enough to thin and dilate—the flow of relaxin contributes to these cervical changes. Your pelvis will also open, expand, and shift a bit as your baby wiggles their way down. Relaxin is on your side as your baby makes their journey down a small, tight space, giving them room and movement as they come to meet you.
When Relaxin is Stressing You Out
Even though relaxin is an important part of your healthy pregnancy and birth, it can still trip us up, sometimes literally. Those loosey-goosey ligaments can contribute to back and pelvic pain during pregnancy, joint pain, and susceptibility to falls and injuries. Prenatal yoga, especially cat/cow position, can help ease your discomfort and is gentle on your body. Wear sturdy shoes and take your time on stairs and slippery areas to prevent injury and consider seeing a physical therapist or prenatal chiropractor for more ideas on staying safe and caring for your body.
The relaxin hormone may seem a bit pesky sometimes, but when it gets you down, just take a deep breath and remember that your body is doing exactly what it's supposed to be doing: facilitating a healthy pregnancy and preparing your body for the birth of your baby.
We encourage you to learn more about our "What in the World" series. Please see our A to Z index for a whole host of pregnancy, postpartum, and parenting information and terminology.
Loree Siermachesky works as a multi-certified labour and postpartum doula, certified Lamaze childbirth educator, certified breastfeeding counselor, certified placenta encapsulation specialist and a certified car seat technician in Medicine Hat and Lethbridge. She has had the honour of attending over 1400 births in the last 20 years. She is well-known and greatly respected by the medical providers in Medicine Hat, Lethbridge, Brooks, Taber, and Calgary. She cares deeply for this profession and even more for her clientele, honoring them in whatever method of birth they choose, or helping them transition to new parenthood as they wish.