Last updated on July 2019

Using a Small Wearable Device to Track Orientation and Activity in Pregnant Patients, A Feasibility Study


Brief description of study

Using a Small Wearable Device to Track Orientation and Activity in Pregnant Patients, A Feasibility Study

Detailed Study Description

Proposed here is the use of a new non-invasive wearable device called the BellyBit™ Preterm Prevention System to avoid extended periods of venous compression. The BellyBit discourages patients from spending long periods of time (day and night) in orientations that are known to restrict blood flow in the ICV (eg supine or very reclined). The device captures sensor data as well as patient reactions to the alerts which can be reviewed by the patient’s obstetrician.

The hypothesis explains many of Preeclampsia’s risk factors well. Preeclampsia is significantly more common in nulliparous women (whose abdomen has not been previously stretched), in severely obese women (who have been shown to have an increased abdominal pressure prior to pregnancy), in women who have a large time gap between pregnancies (abdomen has time to tighten up), in multi-gestational pregnancies (much higher abdominal load than singleton), and is twice as frequent in women with preexisting chronic hypertension (strong connection to venous flow restriction). Further, preeclampsia almost never occurs prior to 20 weeks (when fetus starts to gain significant mass), and its risk increases incrementally every week until delivery at which point it precipitously drops to almost zero. Women with preeclampsia have a 40% increased incidence of delivering a baby with high birth weight for gestational age . This is possibly because these larger babies (which translates to more pressure on IVC) simply end up increasing the incidence of preeclampsia in the mothers. It is also interesting to note that preeclampsia rates are significantly higher in women with hypolumbarlordosis , a purely mechanical abnormality of the spine that situates the uterus in more direct contact with the IVC. And, somewhat surprisingly, no other animals are known to get preeclampsia - it is a very human-specific disease. This is speculated to be due to most mammals carrying their young standing on four legs with the abdomen suspended inferiorly.

Not all pregnant women get preeclampsia even though all pregnant women have a large growing fetus in their abdomen. In the same way that not all women with high blood pressure develop cardiovascular disease, certain women may be predisposed to preeclampsia because of a combination of anatomical and physiological factors that do not enable their venous system to adequately compensate for the growing fetus, and instead develop a vascular inflammatory response similar to that of people predisposed to cardiovascular disease. The BellyBit System may be an effective preventative therapy in some or all of those patients.

It is very possible that one reason why no therapeutic approaches have succeeded to date is because they are often in reaction to the onset of preeclampsia. Studies have shown that bed rest very early in pregnancy for reasons unrelated to preeclampsia leads to a reduction in preeclampsia risk of 77%. Whereas, bed rest prescribed in response to preeclampsia symptoms has shown to be largely ineffective . The BellyBit has the ability to be used prophylactically in high risk pregnancies to slow down or stop the natural progression of disease in these patients. According to this hypothesis, preeclampsia begins to develop when the uterus is of sufficient size to apply significant forces on the abdominal veins (~20 weeks). This includes both the gravitational force as well as the elastic recoil force of the muscles and connective tissues pushing the uterus towards the spine. And, this increase in force accelerates every week due to the growing fetus and uterus. Not surprisingly, this matches empirical evidence for preeclampsia onset exactly and further lends credence to the idea that the BellyBit would likely be most effective beginning around 15-20 weeks to halt the initial development of the syndrome.

Recent studies have demonstrated that supine sleep dramatically increases a woman’s risk for stillborn and low birth-weight babies. As the BellyBit can also be used at night, it should be highly effective in preventing supine sleep positions. Therefore, the BellyBit may decrease rates of fetal morbidity and mortality in this subset of patients.

Finally, it is important to note that this hypothesis is not in competition with other research areas such as vascular inflammation, placental perfusion, fetal hypoxia, or maternal-fetal conflict. Instead, it is complementary - mechanical disruption of normal venous flow could reduce oxygenation to abdominal organs, as well as the growing fetus, and could thus be a contributing factor that 1) initiates preeclampsia development, 2) speeds its development, or 3) amplifies its effects. From a very practical perspective, the best way to prevent 90% of preeclampsia cases is to apply a therapy that delays manifestation of severe symptoms by a few weeks (when the pregnancy is already at term). The BellyBit may be the "nudge" that pushes the vast majority of preeclampsia cases beyond 39 weeks.

Clinical Study Identifier: TX140603

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