This study is a single-center, prospective, and non-randomized feasibility study designed to evaluate the practicality, tolerability, and data quality of short-duration continuous fetal monitoring using a wireless bioadhesive ultrasound device. The study involves a single visit per participant and does not include any therapeutic intervention.

Eligible participants will undergo placement of a wireless bioadhesive ultrasound (ABAUS) device on the maternal abdomen for a short-duration monitoring session. The device will acquire continuous or semi-continuous ultrasound data for a total of 10-30 minutes per participant, without altering standard clinical care. The study is observational and is intended to assess the technical feasibility of device placement, the stability of the coupling during routine maternal movement, image quality over time, and the ability to monitor fetal motion, heart rate, and uterine activity using the investigational device under controlled yet realistic clinical conditions.

The study is non-interventional. No diagnostic or therapeutic decisions will be made based on the ultrasound data collected as part of this research protocol, and all standard prenatal care will proceed independently of participation in this study.

Inclusion Criteria:

1. Pregnant individual 18 years or older
2. Singleton uterine pregnancy
3. Gestational age 20 to 39 gestational weeks
4. Able to provide written informed consent
5. Willing to go an single visit lasting 45 minutes - 1 hour including device placement, monitoring and removal
6. Willing to permit placement of the wireless bioadhesive ultrasound device on their abdomen for approximately 10-30 minutes

Exclusion Criteria:

1. Multiple gestation
2. Maternal abdominal skin condition at the potential site of attachment, such as rash, open wound, etc., preventing placement
3. Known allergy or hypersensitivity to adhesive material or hydrogel products
4. Need for urgent clinical management/triage
5. BMI > 35, as the signal quality could be impacted by BMI and not the device specifically

The study population is limited to persons with a single pregnancy who are receiving a clinically-ordered MRI at Boston Children's Hospital as part of their clinical care.