Sterile water injections (SWIs) are a natural treatment for back pain during labor. The injections do not contain any drugs, and so have minimal side effects.

For some, back pain during labor can be intense. SWIs involve a doctor injecting small amounts of sterile water into the skin around the lower back to relieve it.

The greatest effects usually last between 30 minutes and 2 hours.

In this article, we discuss what sterile water injections are, how they work, how long they last, whether they are safe, side effects, and some frequently asked questions.

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SWIs are a natural form of pain relief during childbirth. Specifically, they reduce severe lower back pain. Lower back pain, also known as back labor, affects approximately 3 in 10 people who give birth.

The injections contain pure, sterilized water that is free of any contaminants. As a result, they do not contain any medication that can interact with other drugs or pose a risk to the pregnancy.

Healthcare professionals administer SWIs by injecting the water with a needle into specific points on the lower back. They may do this at the peak of a contraction, as the injections cause some temporary pain.

Some people describe the pain of SWIs as being similar to an insect sting, but it quickly wears off.

Scientists are not entirely sure how SWIs work. One theory is that the injections may be able to disrupt pain signals traveling to the brain. Another is that the pressure of the injections provides a distraction from the back pain.

Alternatively, it is possible that SWIs may work in a similar way to acupuncture, which also involves inserting needles into the skin, as well as TENS machines, which deliver electrical currents as a way of managing pain. The injections may cause the body to release pain-relieving endorphins.

While the exact timeframe may vary from person to person, the greatest pain relief from SWIs can last from approximately 30 minutes to 2 hours after administration.

If labor continues or the pain comes back, healthcare professionals can administer more injections as often as a person needs.

However, it is worth noting that SWIs alone do not necessarily eradicate back pain. The United Kingdom’s National Health Service (NHS) states they may reduce the pain by up to 50% to 60%.

A 2018 review also says that the amount of pain relief may change depending on the number of injections or the amount of water in each injection.

Research on how best to administer SWIs is still ongoing. Some people may opt to have multiple types of pain management.

Doctors consider SWIs to be safe when a trained healthcare professional administers them. The injections provide localized pain relief without affecting the overall course of childbirth.

SWIs will not have any effect on:

Individuals experiencing significant lower back pain during labor are potential candidates for SWIs. However, they will need to be able to position themselves so that the lower back is accessible to medical professionals.

This may mean sitting up without support, or being on all fours, which can be difficult for some pregnant people during labor.

People who may want to avoid SWIs include those with needle phobias or skin conditions affecting the lower back, such as rashes.

People can discuss whether SWIs are an option during labor with their doctor before the day comes. It may help to know that, if intense back pain does occur, there is a plan in place to manage it.

While people generally tolerate SWIs well, some people may experience temporary side effects. These can include:

  • a temporary stinging sensation at the injection site
  • inflammation or swelling
  • itchiness
  • soreness

These side effects typically resolve quickly and do not pose significant risks.

Below are some frequently asked questions about SWIs.

How painful are sterile water injections?

SWIs may cause a temporary stinging or burning sensation upon administration. However, this discomfort subsides quickly, usually within 1 minute.

Why are sterile water injections painful?

The sensation of pain that accompanies SWIs is due to the needle piercing the skin, and then fluid accumulating underneath the skin.

Can you have sterile water injections during pregnancy?

SWIs are specifically for pain relief during labor. However, people can try similar methods of pain relief, such as acupuncture, for back pain during the earlier stages of pregnancy.

A 2022 review of 10 previous studies found that acupuncture improved back and pelvic pain among pregnant people. There were no observable negative effects on the newborn babies.

Sterile water injections (SWIs) offer a safe and natural way of managing back pain during labor. They do not affect the course of childbirth, a person’s mobility, or their level of consciousness. Health professionals can also repeat them, if necessary, or combine them with other types of pain management.

The minimal impact on labor makes SWIs an option for individuals seeking alternatives to traditional pain medications. While they may cause temporary discomfort upon administration, this quickly wears off.

People who are interested in using SWIs during labor for back pain should speak about their suitability and benefits with a doctor.