Key takeaways 

• Petal is a health tracker that fits inside a bra. 
• It monitors the menstrual cycle, heart, and body. 
• It ships in May and pre-orders are now open. 

Health wearables are becoming increasingly discreet and harder to spot. One of the latest health-tracking devices hides inside a bra to monitor the menstrual cycle, heart, and body. 

Petal is a bra insert that uses bio-impedance sensors and electrical measurements to monitor blood flow near the heart. Because wearers position the insert right next to the heart, the device can capture more accurate readings than your typical smartwatch, Petal says. 

The device comes in one size and fits snug against each breast. It's made with biocompatible materials, including a soft European fabric and a polyurethane-coated interior. 

Also: 7 ways health tech promises to improve your life in 2026

It monitors data across four pillars: heart, mind, body, and cycle. Like other wearables, the device senses a user's baseline and notifies the user when deviations occur. Its position near the breast also makes it well-suited for monitoring variations in breast tissue throughout the menstrual cycle. Petal says it tracks both breast tissue and water content, and measures midsection fat and visceral fat percentage. 

"Petal uses breast tissue measurements as a more direct biological indicator. Your breast tissue and hydration levels undergo distinct, predictable changes throughout your cycle. Our sensors create a private, bias-free characterization of these fluctuations," a Petal spokesperson explains in an email with .

The Petal insert lasts up to 18 days on a single charge. This is far longer than any smartwatch or smart ring I've tested, which averages around two to ten days at most. 

Also: This menstrual pad takes period blood and turns it into data diagnostics

The health-monitoring bra insert would be a nice option for those interested in tracking their health without a watch or ring around their wrist. It ships in May in two colors, black and blush. Pre-orders are now open , and you can get the device for $50 off (for $149) ahead of it shipping. 

Petal's health-monitoring bra insert is one of many health-tracking accessories with a subtler form factor. Late last year, Lumia unveiled smart earrings that record blood flow using the stem's back. These movements toward inconspicuous tracking reflect a growing theme in the health wearables space.  

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