If your doctor can only see one baby, it is unlikely that you are expecting twins or multiples. Because to advances in ultrasound equipment, it is less common to miss the second (or third) fetus. If your doctor suggests that you might have missed a twin, then an ultrasound will be done immediately to confirm or rule out this possibility. Missed abortions are very common and usually due to incorrect diagnosis. Doctors often misdiagnose early pregnancy losses as normal pregnancies. This happens most often with miscarriages before 12 weeks' gestation. If a woman misses her miscarriage and goes on to give birth to her baby, this would be considered a delayed abortion. These cases are also often diagnosed as normal pregnancies because there are no signs of pregnancy loss until much later than this stage. Women who experience recurrent pregnancy loss - where two or more babies die in the first trimester without any known cause - may have genetic mutations that cause all of their embryos to be abnormal. In this case, it is not possible to predict which embryo will survive and which won't, so women need to take multiple precautions to avoid producing additional embryos that cannot develop into healthy babies. Women who have had a previous ectopic pregnancy may be at higher risk of having another one.