From NewScientist (20 March 2015) (paywall), a serious device:
TALK about early adopters. The next generation could start lifelogging even before they are born. A wearable device lets expectant mothers listen in on their developing baby’s heartbeat and movements continuously, rather than just when she goes into the hospital for a scan.
The device consists of a lightweight harness with sensor-laden straps that go over and around the bump. Its inventors believe the system will offer peace of mind to pregnant women, as well as help doctors to monitor high-risk cases remotely rather than keeping women in hospital for observation. It might even reveal new insights about pregnancy itself.