Effect of Maternal Chocolate Consumption on Fetal Non-Stress Test (NST) Reactivity. (CHOCO-NST)

Effect of Maternal Consumption of Dark Chocolate on the Reactivity of the Fetal Non-Stress Test (NST): A Single-Blind, Randomized Clinical Trial.

This is a single-blind, randomized, parallel-group, superiority clinical trial. The study aims to determine whether a single intake of 30g of dark chocolate (≥80% cocoa) by pregnant women with a non-reactive fetal non-stress test (NST) increases the conversion rate to a reactive NST within 20 minutes, compared to observation with a sugar-free white chocolate placebo. A total of 190 singleton pregnant women at 36-41 weeks gestation with a non-reactive NST will be recruited at the Hospital General San Felipe, Tegucigalpa, Honduras. Participants will be randomly assigned to either the intervention group (dark chocolate) or the control group (placebo). The primary outcome is the proportion of NSTs that become reactive. Secondary outcomes include changes in specific cardiotocographic parameters, total monitoring time, need for additional tests, and maternal satisfaction.

Study Overview

• Status: Recruiting
• Conditions: Fetal Distress
• Intervention / Treatment: Dietary supplement: Dark Chocolate; Dietary supplement: Sugar-free White Chocolate

Detailed Description

Background and Rationale:

The fetal non-stress test (NST) is a cornerstone of antepartum fetal surveillance, used to assess fetal well-being by evaluating heart rate accelerations in response to fetal movements. A non-reactive NST, defined by the absence of sufficient accelerations over a 20 to 40-minute period, is a common clinical occurrence. While it can indicate fetal compromise, a significant proportion (up to 50%) are false positives, leading to unnecessary maternal anxiety, prolonged monitoring, costly additional tests (e.g., biophysical profile, contraction stress test), and potentially unwarranted obstetric interventions like induction of labor or cesarean delivery.

Pharmacological agents like methylxanthines (e.g., theophylline) have been used to stimulate fetal activity, but their use is limited by side effects and regulatory considerations. Dark chocolate, rich in theobromine (a methylxanthine) and flavonoids, presents a safe, low-cost, and culturally acceptable alternative. Preliminary studies suggest that maternal consumption of dark chocolate, particularly with high cocoa content (≥70-80%), may stimulate fetal movement and heart rate reactivity, potentially converting a non-reactive NST to a reactive state within minutes. However, existing evidence is heterogeneous, derived from small studies with methodological limitations, and none have been conducted in the Central American population.

This study aims to fill this gap by rigorously evaluating, in a randomized controlled trial setting, whether a single dose of 30g of dark chocolate (≥80% cocoa) is superior to a placebo in converting a non-reactive NST to reactive in pregnant women in Honduras.

Study Objectives:

Primary Objective: To compare the proportion of non-reactive NSTs that convert to reactive within 20 minutes after maternal ingestion of 30g of dark chocolate (≥80% cocoa) versus a placebo control.

Secondary Objectives:

To quantify and compare the change in specific cardiotocographic parameters (number of accelerations, baseline variability) between the groups.

To compare the total time spent in the fetal monitoring unit between the intervention and control groups.

To determine and compare the need for additional fetal surveillance tests or urgent obstetric interventions within 24 hours following the intervention.

To evaluate and compare the incidence of maternal adverse events (e.g., nausea, heartburn, palpitations) within 24 hours.

To assess maternal satisfaction and acceptability of the intervention using a standardized hedonic scale.

• Study Type: Interventional
• Enrollment (Estimated): 190
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Ricardo A Gutierrez-Ramirez, MD, MSc; Phone Number: +50497546940; Email: ricardo.gutierrez@unah.edu.hn

Study Locations

• Honduras
  • Francisco Morazán Department
    • Tegucigalpa, Francisco Morazán Department, Honduras, 11101
      • Recruiting
      • Hospital San Felipe
      • Contact: Ricardo A Gutierrez-Ramirez, MD, MSc.; Phone Number: 97546940; Email: ricardo.gutierrez@unah.edu.hn
      • Principal Investigator: Eliuth Y Martínez López, MD
      • Principal Investigator: María F Diaz Álvarez, MD
      • Sub-Investigator: Arnoldo Zelaya Rodriguez, MD, FACOG
      • Sub-Investigator: Karla P Castro Elvir, MD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Singleton pregnancy between 36+0 and 41+6 weeks of gestation.
• Baseline Non-Stress Test (NST) classified as non-reactive after a standard 20-minute recording (absence of ≥2 accelerations of ≥15 beats per minute lasting ≥15 seconds).
• Intact amniotic membranes and not in active labor (cervical dilation <4 cm, with absent or irregular contractions).
• Ability to provide written, informed consent.
• Literacy: Ability to read and write (to ensure comprehension of the consent form and study materials).
• Access to a telephone or electronic device for the 24-hour safety follow-up contact.

Exclusion Criteria:

1. Pregnancy-related exclusions:

   • Multiple gestation (twins, triplets, etc.).
   • Known major fetal malformation.
   • Diagnosis of severe fetal growth restriction with abnormal umbilical artery Doppler.
   • Premature rupture of membranes.
   • Active vaginal bleeding or placenta previa with hemorrhage.
   • Suspected or confirmed chorioamnionitis.

2. Maternal medical exclusions:

   • Severe preeclampsia, eclampsia, or HELLP syndrome.
   • Uncontrolled severe hypertension.
   • Pregestational diabetes or gestational diabetes requiring insulin or other antihyperglycemic medication.
   • Capillary blood glucose level >140 mg/dL at the time of screening.
   • Maternal fever ≥38°C or maternal tachycardia >120 beats per minute.

3. Interference with test interpretation:

   • Use of sympathomimetic drugs within 12 hours prior to the study intervention.
   • Maternal cardiac arrhythmias.

4. Contraindications to the intervention:

   • Known allergy to cocoa or chocolate.
   • Severe caffeine intolerance.
   • Phenylketonuria.
   • Gastrointestinal conditions that would prevent oral intake (e.g., intractable vomiting, ileus, obstruction).

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Dark Chocolate; Single oral dose of 30g of dark chocolate (minimum 80% cocoa content). Consumed within 5 minutes after a baseline non-reactive NST.	Dietary supplement: Dark Chocolate; Single oral dose of 30g of dark chocolate (minimum 80% cocoa content). Consumed within 5 minutes after a baseline non-reactive NST.
Placebo Comparator: Placebo; Single oral dose of 30g of sugar-free white chocolate, administered similarly. Serves as a placebo control without significant theobromine/caffeine.	Dietary supplement: Sugar-free White Chocolate; Single oral dose of 30g of sugar-free white chocolate, administered similarly. Serves as a placebo control without significant theobromine/caffeine.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Proportion of Non-Stress Tests (NSTs) converting to Reactive status.	NST reactivity is defined per NICHD/ACOG criteria: ≥2 accelerations of ≥15 beats per minute lasting ≥15 seconds over a 20-minute period.	20 minutes post-intervention.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in number of fetal heart rate accelerations.	The absolute change in the count of fetal heart rate accelerations (defined as ≥15 beats per minute increase lasting ≥15 seconds) from the baseline Non-Stress Test (NST) to the NST performed 20 minutes after the intervention.	From baseline (0 minutes) to 20 minutes post-intervention.
Change in Fetal Heart Rate Baseline Variability	The change in fetal heart rate baseline variability, measured in milliseconds (ms), from the baseline Non-Stress Test (NST) to the NST performed 20 minutes after the intervention.	From baseline (0 minutes) to 20 minutes post-intervention.
Total Time in Fetal Monitoring Room	The total duration (in minutes) that the participant remains in the fetal monitoring unit, measured from the start of the baseline Non-Stress Test (NST) until discharge from the monitoring room.	From start of baseline NST (time 0) until discharge from the monitoring room (assessed up to 60 minutes).
Need for Additional Fetal Surveillance Tests	The proportion of participants in each group for whom the treating obstetrician orders additional fetal surveillance tests (e.g., Biophysical Profile, Contraction Stress Test/Oxytocin Challenge Test) following the intervention.	Within 24 hours after the intervention.
Incidence of Maternal Adverse Events	The frequency of maternal adverse events (e.g., nausea, heartburn, palpitations, hyperglycemia, allergic reaction) reported or observed within 24 hours following the consumption of the study chocolate or placebo.	Within 24 hours after the intervention.
Maternal Satisfaction with Intervention	Participant-reported satisfaction with the taste and overall experience of the intervention, measured using a standardized 9-point hedonic scale (1 = "Dislike extremely" to 9 = "Like extremely").	Immediately after completion of the post-intervention NST (approximately 30 minutes after enrollment).

Collaborators and Investigators

• Sponsor: Universidad Nacional Autonoma de Honduras

Publications and helpful links

General Publications

• Peek K, Gatherer D, Bennett KJM, Fransen J, Watsford M. Muscle strength characteristics of the hamstrings and quadriceps in players from a high-level youth football (soccer) Academy. Res Sports Med. 2018 Jul-Sep;26(3):276-288. doi: 10.1080/15438627.2018.1447475. Epub 2018 Mar 5.

Study record dates

Study Major Dates

• Study Start (Estimated): February 15, 2026
• Primary Completion (Estimated): August 31, 2026
• Study Completion (Estimated): September 30, 2026

Study Registration Dates

• First Submitted: February 10, 2026
• First Submitted That Met QC Criteria: February 10, 2026
• First Posted (Actual): February 18, 2026

Study Record Updates

• Last Update Posted (Actual): March 3, 2026
• Last Update Submitted That Met QC Criteria: February 27, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: Chocolate; Theobromine; Cardiotocography; Non-Stress Test
• Additional Relevant MeSH Terms: Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Fetal Distress
• Other Study ID Numbers: PGO-UNAH-49-9-2026

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: all IPD collected throughout the trial
• IPD Sharing Time Frame: Beginning 3 months and ending 5 years after the publication of results
• IPD Sharing Supporting Information Type: CSR

Drug and device information, study documents

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