Aisling Hubert, from Hove in East Sussex, instructed a legal team to bring a landmark case after the medics were filmed by an undercover newspaper reporter.
Palaniappan Rajmohan and Prabha Sivaraman had both faced trial but the Crown Prosecution Service has now intervened claiming a conviction is not in the public interest.
It effectively means they'll face charge.
In a statement, the CPS said: "In relation to the private prosecutions, we have concluded that they should be taken over by the CPS and stopped.
"On the current evidence before the court, there is, in our judgment, insufficient evidence to form a realistic prospect of conviction.
"Taking in to account all the other evidence we are aware of, whilst there is sufficient evidence for a realistic prospect of conviction, this is truly very finely balanced indeed.
"However, the public interest considerations in not pursuing a prosecution outweigh those in favour."
Ms Hubert has expressed her disappointment over the verdict and is considering an appeal.
She said: "I believe this is a really sad day for women in the UK.
"We have abhorred the practice in China and India, where millions of (unborn) baby girls are killed simply for being girls.
"Yet when a case like this is exposed in the UK, the CPS actively works to stop a lawful prosecution."
Ms Hubert was backed by the Christian Legal Centre in her private prosecution.
Speaking about this development, Chief Executive Andrea Williams said: "I think it is very disingenuous of the CPS to do this.
"On the one hand the Government has been saying there is no need for clarity on the law for this.
"Yet we have a situation where the CPS says that despite the evidence it is not in the public interest to prosecute this case. There is clearly a great lack of clarity.
"This is not the end of the matter. We will be looking at ways to challenge this decision."