Do you mean four months of pregnancy? It is more or less as it will look when it is born, just a whole lot smaller. YOu can just about tell whether it is a boy or a girl.
At 4 weeks from your last period (2 weeks from conception) he is the size of a pin prick but already has a quite developed neural tube. He looks kind of like a rolled up tadpole.
but 4 weeks from...
It's possible to lose a baby at anytime during a pregnancy. An undiagnosed UTI may be the culprit, but there are a myriad of different things that could have caused it.