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Leg Heating in Pregnant Women With Obesity

Vascular and Neural Mechanisms of Chronic Leg Heating in Pregnant Women With Obesity

Who can join

As published by the study on ClinicalTrials.gov. "Not stated" means the study hasn't said — ask the study team.

Age
18 Years to 45 Years
Sex
Female only
Healthy volunteers
Accepted
Compensation
Not stated

Other requirements are listed under Eligibility below. Only the study team can confirm whether you can join.

What to expect

No one can promise a trial will help you personally — that is what the research is trying to find out.

What participation involves

Not stated in the study description — ask the study team about visits and procedures.

Compensation
Not stated
  • Study-related exams and procedures are typically provided at no cost. This is how many trials work in general — confirm the details for this study with the study team.
  • Participants are monitored closely by the research team throughout the study.
  • Some participants may receive access to an investigational treatment, which is still being studied.
  • Your participation helps researchers learn whether this approach could help future patients.

About this study

In plain language

This study tests whether heating the legs at home can improve blood vessel function and blood pressure during pregnancy. It is for pregnant women ages 18–45 with overweight or obesity. Women will be assigned by chance to use a warmer or cooler sauna blanket on their legs for 16 weeks.

Obesity is a major risk factor for hypertensive disorders of pregnancy (HDP). The underlying mechanisms are largely unclear, but maternal vascular endothelial dysfunction is likely involved. Endothelial dysfunction in HDP could be attributed to 1) alterations in the L-arginine/nitric oxide (NO) pathway, and 2) an increase in endothelin-1 (ET-1). Additionally, augmented sympathetic vasoconstriction may also contribute to HDP. Chronic (repeated) whole-body heat exposure has been shown to increase NO bioavailability, decrease ET-1, and cause functional and structural adaptations in the vasculature. All these can improve vascular function, attenuate sympathetic (re)activity, lower blood pressure (BP), and reduce cardiovascular risk in non-pregnant individuals. Whether this is also true after regional (leg) heating in high-risk pregnant women is unknown. The investigators' central hypothesis is that chronic leg heating will be effective in improving vascular endothelial function and attenuating sympathetic vasoconstriction, leading to a reduction of the risk for HDP in pregnant women with obesity. The overarching goal of this proposal is to determine the vascular and neural effects of chronic leg heating in obese pregnancy. The study team plans to enroll pregnant women with obesity between 12-14 weeks of gestation and randomly assign them to either an intervention group or a control group (1:1 ratio). Participants in the intervention group will perform 16 weeks of home-based leg heating using a portable sauna blanket up to the hip (temperature of the blanket will be set at 65°C, 4 times/week, 45 min/session), whereas women in the control group will set the temperature of the blanket at 35°C at the same frequency and duration. Participants will be evaluated at baseline and then at 28-30 weeks of gestation. Aim 1 will determine the effects of chronic leg heating on maternal vascular function and surrogate markers of HDP. Aim 2 will determine the effects of chronic leg heating on sympathetic vasoconstriction and BP. Findings from this project will provide insight on the extent and potential mechanisms of how chronic leg heating works for improving vascular endothelial function and sympathetic vasoconstriction in pregnant women with obesity. Results obtained will set a foundation for future large multicenter clinical trials to determine the efficacy and generalizability of home-based leg heat therapy as a safe, ease-of-use, cost-effective, and non-drug approach for reducing the risk of HDP.

Compensation is read from the study's own description and may be missing — always confirm with the study team.

Eligibility

Who can join

  • Age 18–45 and 10–14 weeks pregnant.
  • Overweight or obesity before pregnancy, based on a self-reported body mass index (BMI) of 25 or higher. BMI is a measure based on height and weight.
  • Normal blood pressure or high blood pressure with an upper number of 140–150 and/or a lower number of 90–100, without taking blood pressure medicine.
  • May be pregnant for the first time or have given birth before.
  • People of any race, ethnic background, or income level may join.
  • May have had high blood pressure problems in a past pregnancy.
  • May take low-dose aspirin.

Who can't join

  • Pregnant with twins, triplets, or more; or the baby has a known major problem with chromosomes or body structure found during the study.
  • Three or more miscarriages.
  • Blood pressure measured while sitting at the clinic below 100/55 or above 150/100.
  • Heart or blood vessel disease, lung disease, a brain or nerve disease, or diabetes.
  • Kidney disease with a blood creatinine level above 0.9 mg/dL. Creatinine is a waste product used to check kidney function.
  • Known blood clots in deep veins, symptoms or a history of these clots, or skin sores or other skin damage.
  • Drug or alcohol abuse in the past 2 years, or current tobacco use.
  • No air conditioning at home during summer.

Simplified for readability. The official criteria below are what the study team uses.

Official eligibility criteria

Inclusion Criteria: * Women with overweight or obesity (self-reported pre-pregnancy body mass index ≥25 kg/m2) between 10-14 weeks of gestation and aged 18-45 years old will be enrolled. * Both normotensive and hypertensive (office sitting systolic BP 140-150 mmHg and/or diastolic BP 90-100 mmHg) pregnant women will be enrolled if they are not on any antihypertensive drug treatment. * We will enroll both nulliparous and multiparous women. * There is no restriction regarding race/ethnicity and socioeconomic status. * Women with a history of HDP will be allowed to participate. * Women taking low-dose aspirin will be allowed to participate and aspirin use will be documented. Exclusion Criteria: * Current multiple pregnancies (e.g., twins, triplets, etc.). * Known major fetal chromosomal or anatomical abnormalities diagnosed during the study. * Recurrent miscarriage (three or more, to avoid antiphospholipid antibody syndrome). * Office sitting BP \<100/55 mmHg or \>150/100 mmHg (for safety reasons). * Evidence of cardiovascular, pulmonary, or neurological diseases. * Diabetes mellitus (to avoid its effects on vascular endothelial function and sympathetic vasoconstriction). * Kidney disease (serum creatinine \>0.9 mg/dL). * Clinical known deep vein thrombosis, clinical symptoms and history of deep vein thrombosis, or dermatological lesions. * History of drug or alcohol abuse within the last 2 years. * Current tobacco use. * Pregnant women who do not have air conditioning at home during summer (for safety reasons).

Study sites (1)

TX