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Relaxin Hormone: What is it and understand the levels during and after pregnancy

To a certain extent, discomfort and pain during pregnancy are normal and to be expected. But if you’re feeling extra sore and even having symptoms such as heartburn, one of your surging hormones may actually be to blame. It’s called relaxin and, while it plays an important role in allowing your body to deliver a baby, it can also have some less-than-pleasant side effects during and after pregnancy. Thankfully, there are things you can do to mitigate some of the effects. In this article, we’ll teach you all about the hormone relaxin, how it affects your body, and how you can help reduce its effects.

What is Relaxin?

Relaxin is a hormone produced by the ovary and the placenta with important effects in the female reproductive system and during pregnancy. Men also have relaxin in their bodies, produced by the prostate gland and found in semen, but rarely in their blood stream. 

Woman's relaxin levels in circulation rise after ovulation, during the second half of the menstrual cycle. At this stage it is thought to relax the wall of the uterus by inhibiting contractions, and it also prepares the lining of the uterus for pregnancy. If pregnancy does not occur, relaxin levels drop again.

As you’ll be aware, hormones play a huge role in pregnancy. There are three in particular that really surge when a woman is pregnant: estrogen, progesterone, and relaxin. While those first two pregnancy hormones are pretty well known, relaxin isn’t talked about or understood quite as much, which is a shame because it impacts your body with similar strength than the other two.

Like with estrogen and progesterone, relaxin is a hormone that already exists in your body pre-pregnancy, although at very low, nearly undetectable levels. It’s when you get pregnant that your relaxin levels shoot way up. They will be at their highest in early pregnancy, peaking near the end of your first trimester. After that, your relaxin levels will decline and remain low for the rest of your pregnancy except for a spike during delivery. In preparation for childbirth, it relaxes the ligaments in the pelvis and softens and widens the cervix.

Some may start experiencing relaxin-related effects very early on in pregnancy, and some may suffer from lack of sufficient amount of relaxin. Both are quite bothersome troubles, with the golden amount somewhere not too much and not too little. 

Relaxin’s Function

You may be wondering at this point what this hormone’s function is. Thankfully, it’s fairly easy to remember, as the main purpose of it is right in the name: relaxin is responsible for relaxing your muscles and ligaments to make room for the growth of your baby and make it easier for your body to expand enough to deliver. However, this is not the only function relaxin has in a woman’s reproductive system. The hormone is responsible for the following:

  • Helps the foetus implant in the uterus
  • Aids in the growth of the placenta
  • Stops contractions to prevent early delivery
  • Relaxes intrauterine ligaments to allow for expansion of the uterus to accommodate the growing placenta and foetus
  • Increases elasticity of and relaxes the abdominal and pelvic floor muscles
  • Relaxes arteries to accommodate a 30-50% increase in blood volume so the blood pressure does not spike
  • May play a role in inducing labour
a pregnant woman holding her young daughter in her arms

Relaxin During Pregnancy

As you can see, relaxin’s role in making your pregnancy and delivery smoother is critical. However, it can also cause some issues and pain. After all, having softer ligaments and more flexible joints isn’t just a plus for yoga. It can also be a real nuisance, leading to:

  • Overstretching, pulls, and strains
  • A loss of control over the bladder as a result of a relaxed pelvic floor
  • Weakened pelvic stability, which can be an issue for the posture
  • Heartburn caused by relaxed abdominal and digestive tissue

Of these issues, the most common is pelvic girdle pain caused by pelvic joint instability, which 45% of women suffer from during pregnancy. Symptoms of pelvic girdle pain include:

  • Pain in the groin, pubic area, buttocks, lower back, or back of the thighs
  • Unilateral or bilateral pain
  • A clicking or locking sensation in the pelvic joints
  • Pain aggravated by activities such as walking, standing on one leg, ascending or descending stairs, getting into or out of a car, rolling in bed, and carrying heavy items in one hand

Learn more: Pregnancy hormones: “Why can’t I keep it together?”

Relaxin can also play a role in round ligament pain symptoms. The round ligaments are a pair of cordlike structures in the pelvis that help support the uterus by connecting the front of the uterus to the groin. Like your other ligaments, the round ligaments become softer and stretch during pregnancy, which can be rather painful, especially during rapid, repetitive movement, vigorous activity, and when rolling over in bed. Most round ligament pregnancy pain is experienced on the right side of the body, though it can occur on the left, as well.

Relaxin During Postpartum

While relaxin drops significantly after you give birth, you will have elevated levels of it for several months after your delivery (different sources estimate it to take between five and twelve months for relaxin levels to go back to normal), which can continue to affect your body. For example, relaxin (and weight gain) may be responsible for your feet growing up to one full shoe size and your feet arches flattening.

Beyond that, relaxin will also cause your joints and ligaments to remain extra flexible and loose even after your pregnancy. This means that you may be more susceptible to injuries, as your musculoskeletal system is in a less stable state. As a result, you will want to be extra careful with exercising after giving birth. While you may be interested in activities such as yoga or pilates postpartum as a gentle post-pregnancy workout plan, you should take care to avoid overstretching.

After you have your baby, chances are you will experience some degree of abdominal separation, or so called Diastasis Recti. Relaxin, which loosens and weakens your core muscles, still stays in your body for a while after pregnancy. This causes the appearance of a ‘mummy tummy’ that may further damage your lower back and spine. While your body will start to repair some of the abdominal separation on its own, you should pay close attention to this and look into core strengthening exercises to avoid long-term complications.

Learn more: Diastasis Recti symptoms and how to treat it

Relaxin During Breastfeeding

Some sources report that relaxin levels remain elevated in the body postpartum as long as a woman is breastfeeding and even for several months afterwards. It is also believed that the hormone may have an effect on the growth of the milk-producing tissue of the breasts and, indeed, relaxin is present in breast milk. If you are breastfeeding, you may find that the joint-loosening effects of relaxin persist longer than they would if you were not breastfeeding, so breastfeeding mums are advised to take extra care with postpartum exercise until after they cease breastfeeding.

Managing Pain Caused by Relaxin

If you’re experiencing pelvic, groin, joint, or ligament pain during pregnancy, it can be a serious problem that makes your pregnancy very uncomfortable. Here are some tips for managing the more painful effects of relaxin.

  • Be mindful of your posture, as relaxin can cause postural issues. Try to stand with your head high, shoulders back, and your spine and pelvis in a neutral position, with your core supporting a straight column from the head to the tail.
  • Maintain an exercise routine. If your tendons and ligaments are too loose and your muscles too weak, it can lead to an imbalance that is even more painful.
  • To avoid heartburn, try to eat smaller meals, chewing your food slowly at mealtimes. You can encourage digestion after larger meals by taking a walk.
  • If you do experience heartburn, ginger can be an incredibly soothing natural solution to try before taking medication.
  • If you’re struggling with back pain, find out 6 great ways to relieve back pain during pregnancy

If your pelvic pain is particularly severe, physical therapy might be a good solution. A professional can help you with pregnancy therapies such as soft tissue massage, hot or cold therapy, pelvic joint taping, and pelvic stability braces or crutches. They may also be able to recommend specific strengthening exercises and lifestyle modification advice for your particular circumstances so you can avoid aggravating activities and better support your pelvic floor muscles. If you are considering physiotherapy or any other pain relief therapy, make sure you are consulting with a professional trained in maternity care.


Strengthening Exercises to Reduce the Effect of Relaxin

One of the best things you can do to reduce the uncomfortable effects of relaxin both during and after pregnancy is to exercise. Working out while pregnant and postpartum fitness are not only good for you, but they are also highly recommended to help your body weather and bounce back from the tremendous physical changes during pregnancy.

That being said, exercise for pregnant women is something that should be undertaken safely and with care in order to decrease the risk of muscle and joint injuries. Because of relaxin, high impact, high intensity exercise can lead to sprains and strains, as well as damage to the pelvic floor. If you lift heavy weights or with poor technique, you can put yourself at risk of back strain or disc prolapse.

Learn more: Benefits of working out while pregnant

For that reason, unless you are consulting with an exercise professional or have already had a consistent exercise routine before pregnancy, it’s a good idea to stick to the basics when it comes to working out while pregnant. Some of the best workouts for pregnant women include walking, gentle stretching, and low-impact aerobic exercise. Especially in your third trimester, when your centre of gravity and balance are most impacted, it’s a good idea to be extra mindful about balance, ideally staying near a wall or rail that you can use as a balance aid and avoiding standing on one leg or other exercises that challenge your balance.

Some of the best exercise for pregnant women is core and pelvic strengthening and stabilizing workouts, which can help counteract the loosening effects of relaxin. Some safe exercises for pregnant women include pelvic floor holds, hip twists, bear pose holds, pelvic tilts, Kegels, cat/cow stretches, and bird dogs.

For extra support postpartum, it can be a great idea to use a postnatal belly band, which is designed to support your hips, back, and abdominal muscles as your body recovers in the weeks and months after childbirth. This will also help remind you to keep your core engaged and activated during movement, activity, and exercise in order to avoid placing unnecessary, disproportionate pressure on your fragile pelvic floor and maintain correct, healthy posture.

postpartum support belt helps ease back pain and provides support while the relaxin is still in your body after your pregnancy. By stabilizing your looser, more unstable joints, ligaments, and muscles, the Core Restore band helps you recover and avoid long-term problems, aiding you in regaining your strength as your body slowly returns to pre-pregnancy relaxin levels.

Final Words

The woman's body during pregnancy is a site of major changes. While you may be aware of the effects of your surging estrogen and progesterone, not all women are sufficiently educated about how relaxin will cause body changes in early pregnancy and beyond, all the way into postpartum and breastfeeding.

This hormone, although not talked about often, plays a huge role in helping your body accommodate and deliver your baby, but it can also come with the side effect of some instability, discomfort, and pain. Exercising, maintaining good posture, and using a band to help support your core are all ways you can mitigate the less pleasant effects of relaxin.

As with all things, especially in pregnancy, relaxin comes with both good and not-so-good. It might cause your body to feel a bit looser, but as long as you are educated about what to expect, which aggravating movements to avoid or be more careful doing, and what exercises, resources, and products can help ease pain and stabilize your pelvis and core, you should be able to have a healthy, comfortable pregnancy.