When will a pregnant woman actually deliver her baby? Right now, it's pretty much an informed guess -- and that's not just inconvenient, assumptions about when a baby is due can also lead to extra medical procedures for both the mother and the baby.
A new study, published in Science Magazine, tried a new method of predicting when a baby is due -- using a simple blood test that could be more accurate than the current method of using the expectant mother's estimate of missed periods, paired with a series of ultrasounds.
"Currently, the best tool that clinicians have to understand pregnancy is ultrasound," the co-author of a new study Mira Moufarrej, researcher at Stanford University, told ABC News. "While ultrasound gives us a good idea of how far along a given pregnancy is ... what it doesn’t tell us is when a given woman will deliver."