She is pregnant and started bleeding – should she break her fast?

The things mentioned – the internal exam, the injection to stabilize the pregnancy and giving a blood sample, do not break the fast, because they are not things that are known to break the fast, nor are they similar to those things.  

With regard to bleeding, the scholars differed as to whether a pregnant woman who bleeds is regarded as menstruating or not. 

In the answer to question no. 23400 we stated that she is regarded as menstruating if that continues to occur at the usual time of her menses, at the usual time of the month and for the usual number of days. 

But if that happens at a time other than her usual time of menses, or if her periods stopped for a month then she began to bleed in the second month, then it is not regarded as menses, so it does not affect the fast and your fast is valid in sha Allah. 

And Allaah knows best.