Trial of Underwater Birth (TUB)

Trial of Underwater Birth: A Randomized Control Trial

Evaluate maternal perinatal outcomes in adult low-risk laboring people randomized to waterbirth compared to those randomized to birth on land.

Study Overview

• Status: Recruiting
• Conditions: Birth
• Intervention / Treatment: Procedure: Waterbirth

Detailed Description

The proposed randomized control trial will be approached as a pilot study to explore or test (if sample size permits) our hypotheses.

Primary outcome: Use of epidural anesthesia during labor and vaginal birth.

Secondary outcomes: Use of IV narcotics in labor, duration of active labor, mode of delivery, composite maternal adverse outcomes (see below), use of intermittent auscultation (IA), composite neonatal adverse outcomes (see below), United States Birth Satisfaction Scale-Revised (US-BSS-R), use of epidural analgesia during labor (full intention-to-treat analysis).

• Study Type: Interventional
• Enrollment (Estimated): 230
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Family Planning Research; Phone Number: 505-205-4118; Email: FamilyPlanningResearch@salud.unm.edu

Study Locations

• United States
  • New Mexico
    • Albuquerque, New Mexico, United States, 87131
      • Recruiting
      • University of New Mexico
      • Contact: Family Planning Research; Phone Number: 505-205-4118; Email: hsc-familyplanningresearch@salud.unm.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria: Inclusion criteria based on A model practice template for hydrotherapy in labor and birth (2016):

Prenatal inclusion criteria (to be assessed at the time of enrollment):

• ≥18 years of age
• Able to speak and understand English or Spanish
• Singleton gestation
• Vertex presentation
• Able to ambulate with no mobility restrictions (i.e., no difficulty getting from seated to standing)
• Less than class III obesity (BMI <40 kg/m2) at initiation of prenatal care

Labor inclusion criteria (to be assessed at time of admission):

• Greater than 37 weeks 0 days through and less than 412 completed weeks 6 days gestation with fetus in vertex presentation
• Normal blood pressure and normal temperature (obstetric criteria for exclusion: two blood pressures 140/90 four hours apart; two fevers of over 100.4 one hour apart)

Exclusion Criteria: based on A model practice template for hydrotherapy in labor and birth (2016):

Prenatal exclusion criteria (to be assessed at the time of enrollment):

• Active infections such as HIV, Hepatitis B, Hepatitis C, HSV outbreak (on prophylaxis acceptable) (GBS positive is acceptable)
• Pre-existing medical conditions including heart disease, uncontrolled asthma, preexisting diabetes, chronic hypertension, or activity restrictions
• High-risk pregnancy conditions including preeclampsia, gestational hypertension, preterm gestation, multiple gestation, gestational diabetes type A2, estimated fetal weight of 5000g for non-diabetics or >4500 for GDM-A1, unstable substance use disorder (i.e. not in remission), placental abruption or other unexplained vaginal bleeding, previous cesarean section, fetal growth restriction (<10th percentile), fetal anomaly, or other neonatal condition that may complicate neonatal transition to extrauterine life.
• Existing contraindication to vaginal birth

Labor exclusion criteria (to be assessed at the time of admission):

• Meconium-stained amniotic fluid
• Preterm rupture of membranes (PROM) greater than 24 hours without the start of any labor contractions (those whose have PROM greater than 24 hours but are in labor can continue to be included in the study)
• Immediate need for operative delivery at time of admission

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
No Intervention: Land Birth; Study subjects enrolled in the land birth cohort of this study will receive care as usual on labor and delivery. There will be no changes to their intrapartum care including their ability to use water as a form of pain relief during labor (Stage 1 water immersion) if deemed appropriate by their care team. Land birth participants who use water for pain relief will be assisted out of the water prior to second stage (pushing) as is currently routine on UNMH Labor and Delivery.
Experimental: Waterbirth; Subjects enrolled in the waterbirth cohort will be assessed for continued eligibility at time of admission to labor and delivery and continuously during labor. Those who remain eligible will have an inflatable birthing tub set up in their room and available for them to use as desired. Waterbirth will be performed in adherence to the following protocol endorsed by the American College of Nurse Midwives.	Procedure: Waterbirth; Those who remain eligible will have an inflatable birthing tub set up in their room and available for them to use as desired. Waterbirth will be performed in adherence to the following protocol endorsed by the American College of Nurse Midwives.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Epidural Anesthesia	Evaluate the epidural anesthesia rate in adult low-risk laboring people randomized to have the option of waterbirth compared to those randomized to birth on land.	Labor and delivery

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
IV Narcotic Use	Use of IV narcotics in labor	Labor and delivery
Active Labor Duration	duration of active labor	Labor and delivery
Delivery Mode	Mode of delivery	Labor and delivery
Maternal Adverse Outcomes	Composite maternal adverse outcomes	Up to 2 weeks postpartum
Intermittent Auscultation (IA)	Use of intermittent auscultation (IA)	Labor and delivery
Neonatal Adverse Outcomes	Composite neonatal adverse outcomes	Up to 2 weeks postpartum
United States Birth Satisfaction Scale-Revised (US-BSS-R)	Satisfaction with birth experience	3 days to 2 weeks postpartum

Collaborators and Investigators

• Sponsor: University of New Mexico
• Investigators: Principal Investigator: Katrina Nardini, University of New Mexico

Study record dates

Study Major Dates

• Study Start (Actual): April 21, 2026
• Primary Completion (Estimated): March 1, 2028
• Study Completion (Estimated): December 1, 2028

Study Registration Dates

• First Submitted: December 17, 2025
• First Submitted That Met QC Criteria: December 17, 2025
• First Posted (Actual): December 31, 2025

Study Record Updates

• Last Update Posted (Actual): April 23, 2026
• Last Update Submitted That Met QC Criteria: April 22, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: birth outcomes; waterbirth; landbirth; epidural use
• Additional Relevant MeSH Terms: Pregnancy; Reproduction; Reproductive Physiological Phenomena; Reproductive and Urinary Physiological Phenomena; Parturition; Natural Childbirth
• Other Study ID Numbers: 25-454; Lacks Grant (Other Identifier: University of New Mexico)

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No