There are many medical terms and interventions that can come up during labor and delivery, and it helps to understand what they mean before birth. If your provider or nurse mentions placing an IV, saline lock, or hep lock during labor, knowing the differences can help you feel more informed and confident about your options.

Medical teams may need direct access to a vein during childbirth for several reasons, including hydration, medications, or emergencies. While the terminology can sound confusing at first, these devices are fairly common and often serve different purposes depending on your labor experience.

Here’s a closer look at the differences between a hep lock, saline lock, and intravenous line, how they work, and when each may be used during labor and delivery.

Hospital policies surrounding IV access during labor can vary depending on your provider, medical history, and birthing location.

Hep Lock vs. Saline Lock vs. IV at a Glance

Although these terms are often used interchangeably, they are not exactly the same.

• An IV typically refers to intravenous access that may continuously deliver fluids or medications.
• A saline lock is a peripheral IV catheter that is flushed with saline when not actively being used.
• A hep lock, or heparin lock, uses heparin to help prevent clotting and is more commonly used with central lines than routine labor IVs.

What is an IV?

Many hospitals recommend IV access during labor so medications or fluids can be given quickly if an emergency arises.

The term “IV” stands for “intravenous,” meaning “within a vein,” and refers to an intravenous line. Doctors or nurses use a needle to insert a very narrow, soft, flexible tube into a peripheral vein, such as the hand or arm. They then secure the catheter in place and remove the needle. The needle does not remain in your body while the IV is in place.¹

What may run through an IV can vary depending on your labor needs and medical situation. An IV catheter is primed with a saline solution before insertion to prevent air from entering your bloodstream through the tubing. If no fluids are constantly running through the catheter, it must be locked to prevent germs from entering. Nurses must also flush the tube with fluid regularly to prevent a clot from forming.

Related: Medical Interventions You Might Need During Pushing

What is a Hep Lock?

A hep lock, short for a heparin lock, means the IV catheter is flushed with a heparin solution when the IV is not in use. Heparin is a blood-thinning medication that helps prevent blood clots but poses a risk for excessive bleeding. Heparin locks are not used in peripheral IVs because the risk of bleeding outweighs the risk of line clotting and the need to initiate a new IV.

These locks are reserved for central lines. It is more critical that central venous catheter lines do not clot because new intravenous access is much more difficult to obtain. However, central lines are not standard in labor and delivery units. Heparin locks are not always necessary, so it is vital to avoid them, if possible, especially during labor and delivery, because laboring and newly postpartum mothers are already at increased risk for hemorrhage.²

Related: Understanding Postpartum Hemorrhage and How To Recover

What is a Saline Lock?

Many sources mistakenly refer to a saline lock as a hep lock colloquially, leading to confusion between the two.

A saline lock is a peripheral IV catheter that is not running fluid. Nurses routinely flush it with a standard saline solution (salt water at the same concentration as your blood). If you have IV access in your arm or hand but are not hooked up to tubes and receiving fluids, then you likely have a saline lock.

Saline does not contain medications, but it maintains the IV catheter’s patency when flushed at appropriate intervals with enough volume. Flushing an IV to prevent clotting is essential to avoid losing the line and having to stick with a new needle for intravenous access.

What Can Be Given Through an IV?

IV access allows medical teams to quickly deliver fluids, medications, and blood products directly into the bloodstream when needed. Some products they might administer through your IV include:

Fluids

Even if your provider recommends you consume nothing by mouth during childbirth, it is crucial to maintain proper hydration and energy throughout labor and delivery. They can use your IV port to infuse fluids continuously into your bloodstream to replace what you would get from eating and drinking. These fluids may contain things like salt, other electrolytes, and sometimes sugar. IV fluids help maintain hydration, electrolyte balance, blood volume, and blood pressure during labor. They may also help support circulation and energy during childbirth.³

There is some thought that including sugar in your IV fluids during birth may help improve the strength of uterine contractions, therefore decreasing labor time and reducing the rate of C-sections, but studies have not proven this.⁴

IV fluids can help maintain blood volume in the event of excessive blood loss during labor, delivery, and the postpartum period. They can also help maintain blood pressure, especially when epidural insertion causes a sudden drop in blood pressure.⁵

Medications

Doctors also use IV ports to administer medications directly into your bloodstream. These medications can run alongside continuous IV fluids, and some can be given alone with a saline flush to ensure the medication leaves the IV tubing and enters your bloodstream.

Some common medications given during delivery include:

• Oxytocin is a drug often used to induce or augment labor. Doctors may also give oxytocin after delivery to treat postpartum hemorrhage because it causes the uterus to contract and slow the bleeding. IV oxytocin is more effective at preventing postpartum hemorrhage than intramuscular injection of the same medication.⁶
• Antibiotics are often given during labor to prevent bacterial infection in you and your newborn, mainly if you have tested positive for Group B strep or if your water has been broken for a long time. Doctors also routinely give antibiotics before C-sections to prevent the risk of infection at the incision site.
• Doctors use IV opioid medications in place of or in addition to epidurals to help alleviate labor pains, although they will not eliminate pain. Opioids can cause side effects such as nausea and vomiting, decreased breathing rate, itchiness, drowsiness, constipation, and urinary retention. They may also cause temporary sleepiness in some newborns after delivery.⁷

Related: Oxytocin: What the Love Hormone Does for Parents and Babies

Blood Products

A postpartum hemorrhage can occur if a piece of your placenta is retained in your uterus, if lacerations on your cervix or birth canal are bleeding profusely, or if your uterus is not contracting to heal the placental wound. In these cases, it is sometimes necessary to administer blood products to the birthing mother to prevent maternal morbidity and mortality associated with significant blood loss. Doctors can use your IV to give you these blood products.⁸

As you can see, there are many reasons to get an IV during labor, whether for a saline lock or continuous fluids. However, IV insertion and use do come with some risks.

What Are the Risks of IVs?

The main risks of IV insertion include the following:

• Infection
• Pain
• Clotting
• Inflammation

All of these risks may occur at the insertion site, even if you get a saline lock with nothing running through it.⁹

If you have continuous fluids running through your IV during childbirth, there are other risks and considerations for you and your baby, including:

Newborn Hypoglycemia

If your IV fluids contain sugar or dextrose, there is a slight risk for rebound hypoglycemia or low blood sugar in your newborn after delivery.⁴

Newborn Weight Loss

IV fluids during a laboring woman’s delivery can artificially inflate her newborn’s weight at birth. The baby then urinates the excess fluid after birth to maintain fluid balance. Hospital staff closely monitor a newborn’s weight to ensure adequate nutritional intake. Excessive weight loss due to prolonged exposure to IV fluids during labor can make it appear that they have lost more weight than they have. One study recommends using the infant’s weight at 24 hours of life rather than birth weight when assessing weight loss, assuming that by 24 hours, the newborn will have peed out the excess IV fluids from their birthing mother’s labor.¹⁰

Related: How Much Weight Loss Is Normal for a Newborn

Newborn Hyponatremia

Another study showed low blood salt levels, or hyponatremia, in newborns whose laboring mothers received IV fluids compared to mothers who received only oral fluids. This study also confirmed that infants of mothers with IV fluids during labor lost 50% more weight than those whose mothers consumed only oral hydration.¹¹

Limitations on Maternal Movement

Continuous IV fluid infusions during labor require that staff hook the mother to IV tubing and an IV pump on a pole. Although we can move the pole with the laboring woman, it can limit movement, which can be frustrating and may increase pain if a laboring woman can’t change position easily during contractions. However, if a laboring mother has an epidural, her movement is already limited, and an IV may have fewer movement-limiting effects.¹²

Limitations on Water Therapy

Saline locks must be kept dry and not submerged in water. This may limit the ability to use a tub or shower for comfort measures during labor. Saline locks can also get in the way of your first postpartum shower, depending on where the lock is and when your doctor removes it. In some cases, you may be able to use plastic wrap over the saline lock to protect it from water and still take a bath or shower.¹³

Related: Water Birth: Benefits, Risks, and What You Need To Know

Questions To Ask About Your IV During Labor

It is essential to advocate for yourself when your nurse places your IV. You have a say in its placement and location. Speak up if you don’t want a saline lock in your dominant hand or the arm you sleep on! There are many locations where they can place a peripheral IV. It is perfectly acceptable to tell your nurse you would prefer they not put an IV in a specific area.

Despite the potential risks and inconveniences of having an IV during labor, they are typically considered safe and routine interventions. However, continuous IV fluids and even saline locks during labor are not always necessary.¹⁴

One study of low-risk laboring mothers administered IVs only when the need arose, resulting in 28 percent of women never needing an IV.¹⁴

Related: How To Be Your Own Advocate During Labor and Birth

While IV access or continuous IV fluids may be necessary during delivery, they are not always mandatory. Some low-risk laboring mothers may need very little intervention during labor, while others may benefit from IV access depending on their situation.

Understanding the differences between a hep lock, saline lock, and intravenous line can help you feel more informed and prepared before birth.

Your provider and nursing team can help explain your options, your birthing location’s policies, and whether IV access is recommended for your specific labor experience. Never hesitate to ask questions or discuss preferences with your care team before labor whenever possible.