Is it safe to use a TENS (transcutaneous electrical nerve stimulation) unit during pregnancy, and what are the recommended placement, settings, duration, and contraindications?

TENS Unit Use During Pregnancy

TENS units can be safely used during pregnancy, particularly during labor for pain management, with no known contraindications to the examination itself and no adverse effects reported on maternal or fetal outcomes. 1, 2

Safety Profile

There are no known contraindications for TENS examination during pregnancy. 1 This represents expert consensus from critical care and electrical impedance monitoring guidelines, which explicitly state that pregnancy does not preclude the use of electrical nerve stimulation devices.

• No adverse events have been reported in systematic reviews examining TENS use during labor 2
• TENS does not cross the placenta and poses no direct risk to the fetus 3
• The electrical impulses are low-voltage and localized to the application site 2
• No negative impact on maternal or fetal outcomes has been documented in randomized controlled trials 2

Primary Indication: Labor Pain Management

TENS is most appropriately used during the first stage of labor (dilation period) when pain is moderate but not yet severe. 4, 3

Effectiveness Evidence

• Women using TENS report willingness to use it again in future labors, suggesting high acceptability 2
• When applied to acupuncture points, women were significantly less likely to report severe pain (risk ratio 0.41,95% CI 0.32-0.55) 2
• 87% of participants reported some form of pain relief, with 20% reporting excellent relief 5
• A 2025 integrative review confirmed TENS effectiveness in relieving labor pain across multiple studies 6

Limitations

• Overall pain ratings show little difference between TENS and control groups when applied to the back 2
• TENS does not reduce pain when used as an adjunct to epidural analgesia 2
• Effectiveness has not been clearly demonstrated for the active stage of labor according to some professional societies 4

Recommended Settings and Placement

For labor pain, use high-frequency TENS (15-100 Hz) with electrodes placed on the lower back during the active phase of labor. 6

Specific Parameters

• Frequency: 15-100 Hz (high-frequency mode) 6
• Electrode placement: Lower back (most common) or acupuncture points 2
• Timing: Begin during early labor, particularly effective at cervical dilatation ≤6 cm 6
• Patient control: The unit should be operated by the woman herself to increase sense of control 2

Alternative Placements

• Acupuncture points (more effective for severe pain reduction) 2
• Cranial application (less commonly studied) 2

Contraindications and Precautions

No absolute contraindications exist for TENS use during pregnancy. 1 However, certain clinical situations warrant caution:

• Avoid use simultaneously with thoracic ultrasound examination 1
• Turn off active electrical devices if possible during TENS application (passive electrical devices do not interfere) 1
• Ensure proper electrode-skin contact using water or ultrasound gel 1
• Avoid electricity-conductive fluids (sweat, saline) as they impact electrode-skin contact 1

Clinical Practice Recommendations

Women should have the choice to use TENS during labor, as it is widely available, non-invasive, and carries no risk of adverse effects. 2, 3

When to Offer TENS

• During early to mid-first stage of labor before pain becomes severe 4, 3
• For women seeking non-pharmacological pain relief options 2
• As an alternative or complement to other methods (though not with epidural) 2

When TENS is Less Appropriate

• During active late labor when pain is very intense 4
• As an adjunct to epidural analgesia (no added benefit) 2
• For women requiring immediate, maximal pain relief 4

Common Pitfalls to Avoid

• Do not position TENS as highly effective for all women: Evidence shows variable effectiveness, with some women experiencing minimal benefit 2, 4
• Do not use TENS at home in early labor without evaluation: This application has not been adequately studied 2
• Do not expect TENS to reduce interventions or affect labor outcomes: There is no consistent evidence of impact on cesarean rates, instrumental delivery, or other obstetric interventions 2
• Do not apply TENS over areas with rib fractures without ensuring appropriate belt size: Excessive pressure should be avoided 1