Scientists were able to deduce the genotype of a fetus using only a blood test from its mother and a saliva swab from its father. They were able to do so because a pregnant woman will have cell-free DNA from her child in her bloodstream, and those DNA sequences can be separated from the mothers’ by comparing it to the fathers’ (basically the same as you would for a paternity test, only in this case the aim is to separate the mothers’ genotype from the baby’s).
Being able to test a baby’s genotype without having to sample the amniotic fluid or the placental tissue will make it much easier to do genetic screens on fetuses. Whether or not this is a good thing is still up for debate. It will help catch life-threatening disorders more easily, as well as things like Down syndrome. However, if the entire fetal genome is sequenced, there will be so much information on the genes that “cause” other diseases that parents may come to conclusions about their unborn child’s health too soon. Most of what is ‘known’ about the causative impacts of human genes is correlative, and does not really demonstrate that the genes cause that specific disease. It is dangerous to assume too much. And if parents are provided with so much information about the genetic health of their unborn child, it is possible that they may make erroneous assumptions about their child’s health. As sequencing technology improves, it is also possible that the genotyping will be able to be done even earlier in the pregnancy, which could lead to ethically-ambiguous dilemmas such as selective abortions.