I am looking for a machine that either fits under the baby's mattress or underneath the baby that monitors the child's respiration, heart rate, blood pressure, and blood oxygen saturation. An alarm will sound if the baby stops breathing for more than 20 seconds. Do you know where I can find one?
Although you didn't mention why it is you are looking for a monitor for your baby, this question is one most often asked by parents of infants who are born prematurely. This is likely because premature infants are typically monitored in the hospital for apnea (stopping breathing). Apnea is not uncommon within the first days after birth in premature babies who are not on breathing machines or other respiratory support. That said, continued apnea monitoring may not be necessary once a baby has proven his/her ability to go for longer stretches without any apneic episodes and is a bit older—reaching what would have been at least 34 to 36 weeks of age had they not been born prematurely.
When it comes to home monitoring, I therefore strongly suggest you discuss with your baby's doctor whether your baby still needs home monitoring. If apnea continues to be present or a concern, your doctor should be able to help you not only find an appropriate monitor, but help make sure you know how to use it, what to do if it alarms, and when you can feel comfortable discontinuing its use. The American Academy of Pediatrics' 2003 recommendation states that home monitoring can usually be stopped either when "extreme episodes" stop or after a baby is three weeks past what would have been their due date (also referred to as 43 weeks "postmenstrual age").