During the news there's a lot of movement that can break through your stoploss. Besides, many brokers have a strong widening of the spread. Before important news it's best to exit the deal or push back the stop loss.
Right, news time the market ia having a high movement and that is the reason why traders like to trade on news or avoid to trade market because they can not handle the money with risk of it.
There are many strategies that we need to learn and depend on while trading with Forex, we cannot simply rely on any one of them.
When you are trading the news, it is best to make use of fixed spreads. Unless the broker is a bucket shop, spreads should not widen to a staggering degree. I haven't notice spread widening while trading with my broker. It is an offshore broker though, but they seem to be the decent ones, when it comes to news trading and negative balance protection.