Baby formula makers are supposed to make life easier for new parents, but Consumer Reports put them to the test with troubling results.Being the parent of a newborn can be one of the most stressful and challenging jobs, and any little thing can help. Newer gadgets called infant formula makers claim to make precisely measured, warm, ready-to-drink bottles. But are they worth the money, and, more importantly, do they work? A Consumer Reports investigation found that they didn't work effectively during multiple tests.>> Download the free WMUR app to get updates on the go: Apple | Google Play <<"A big selling point for these infant formula makers is that it's a tech-savvy solution that's presumably more accurate than relying on your hands and tired eyes," said Lisa Fogarty, of Consumer Reports.Baby formula makers offer to take some of that work off your plate, advertising that they can "reduce the stress in your life."But after complaints from caregivers and medical experts to the Consumer Product Safety Commission about the Baby Brezza Formula Pro Advanced, Consumer Reports safety experts investigated the accuracy of three of the more popular machines on the market right now: the Baby Brezza Formula Pro Advanced, the Baby Brezza Formula Pro Advanced Wifi and the Baby Exo Formula Dispenser Machine. The results were concerning. "The two Baby Brezza formula makers consistently gave less formula than was expected, which, over time, could lead to your baby being malnourished," Fogarty said. "The Baby Exo consistently gave more formula, which also isn't ideal."In a statement, Baby Brezza said the reason for the discrepancy between Consumer Reports' test results and its own is the significant natural variability that exists in formula powder in general. Baby Exo did not respond to Consumer Reports' request for comment. While these formula makers may save you time, it's important to feed your baby accurate amounts of formula. So, preparing the formula by hand, following the manufacturer's instructions or those from your pediatrician, may be your best choice.It's important not to make homemade formulas, because there's no guarantee your baby will be getting the proper nutrition, and it could be contaminated with harmful bacteria.