Diagnosis
Doctors report first pregnancy using AI system to detect sperm in men previously considered infertile

A couple who had been trying to conceive for 19 years have become the first to achieve pregnancy using an artificial intelligence system designed to detect sperm in men with azoospermia – a condition where no sperm are visible in semen.
The pregnancy was announced in March 2025 by doctors at Columbia University Fertility Center.
It followed the development of the STAR (Sperm Track and Recovery) system, led by Dr Zev Williams, director of the centre.
Male factors are thought to account for around 40 per cent of infertility cases in the US, with azoospermia responsible for roughly 10 per cent of male infertility.
Until recently, there was little doctors could do beyond recommending donor sperm.
Williams explained that semen samples from men with azoospermia can appear normal, but microscopic analysis shows no visible sperm among other cell debris.
As sperm are the smallest cells in the human body, even highly trained technicians often fail to identify them.
The Columbia team spent five years developing STAR, which combines an AI algorithm trained to detect sperm with a fluidic chip that channels the semen through microscopic tubules.
When the AI detects sperm, that portion of the sample is diverted into a separate channel for collection.
The recovered sperm can then be frozen or used for fertilisation.
Inspired by methods used by astrophysicists to find stars and planets, the STAR system is trained to detect what Williams calls “really, really, really rare sperm.”
He said: “If you can look into a sky that’s filled with billions of stars and try to find a new one, or the birth of a new star, then maybe we can use that same approach to look through billions of cells and try to find that one specific one we are looking for.”
He likened the process to finding “a needle hidden within a thousand haystacks,” and noted that STAR is able to do this within a couple of hours and gently enough to preserve sperm for use in IVF.
What makes STAR distinct, he added, is that it not only detects the presence of sperm, but also isolates them automatically—a step that sets it apart from many other AI diagnostic tools.
The system can scan around eight million images in an hour.
Williams recalled the moment he became convinced of the system’s potential: before discarding semen samples deemed sperm-free by embryologists, they were run through STAR.
In one case, after two days of unsuccessful manual searching, STAR found 44 sperm in one hour.
Rosie, 38, who asked to use a pseudonym to protect her identity, and her husband became the first couple to achieve pregnancy using STAR.
They had spent nearly two decades trying to conceive and had undergone 15 unsuccessful IVF cycles. Their Orthodox Jewish faith, Rosie said, kept them hopeful throughout.
Before using STAR, they had explored multiple options to address her husband’s azoospermia, including surgery and bringing in a specialist from abroad to manually search sperm samples.
They also looked into chemical extraction methods, which posed risks to sperm quality.
Rosie said: “There really was nothing else out there.
“Especially because I am running quite a few years ahead of where we should be [for fertility]. I’m not that old, but in fertility years—egg-wise—I was reaching my end.”
They learned about Williams’ programme through a community group and quickly familiarised themselves with the technology.
She said: “We knew exactly what it was, and knew what they were trying to do.
“If they could get sperm in a more natural way without chemicals and hopefully chose the good ones—if the programme was able to do that, we knew we had a better chance.”
The IVF cycle using STAR did not require any extra testing or procedures and followed the same steps as previous attempts.
Rosie said: “We were keeping our hopes to a minimum after so many disappointments.
“We came in, did what we had to do for the cycle, knowing there was probably a very small chance of anything happening. Why should this be any different from every other time?”
Williams explained that in conventional IVF, sperm typically outnumber eggs by a large margin, but in azoospermia cases, the reverse is true.
To maximise the chances of success, his team used STAR to collect several sperm samples in advance, which were frozen.
On the day of egg retrieval, they processed a fresh semen sample through STAR and used any recovered sperm to fertilise the eggs.
The frozen samples were kept in reserve in case no viable sperm were found in the fresh sample.
Within two hours, Rosie was told her eggs had fertilised successfully.
She said: “After the transfer, it took me two days to believe I was actually pregnant.”
Now four months into her pregnancy, Rosie is receiving standard obstetric care, and doctors say everything is progressing normally.
She said: “I still wake up in the morning and can’t believe if this is true or not.
“And I still don’t believe [I’m pregnant] until I see the scans.”
Williams said that azoospermia is just one fertility challenge where AI could be transformative.
Williams said: “There are things going on that we are blind to right now. But with the introduction of AI, we are being shown what those things are.
“The dream is to develop technologies so that those who are told ‘you have no chance of being able to have a child’ can now go on to have healthy children.”
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