The man, age 34, had been in a relationship with the woman. He was remanded by judges in Solna district court.
Police have now revealed that the woman was originally from Kenya.
The body of the 35-year old woman was found in Ekerö, west of the capital. It is believed that she was murdered in May or June. She was never formally reported missing.
“That could be because she didn’t have a residence permit, but came to Sweden on a tourist visa four years ago,” said Inspector Anders Burén.
The woman had been working as a hairdresser since arriving in Stockholm from Kenya.
Prosecutor Tora Holst had asked for the court to label the man as ‘suspected with probable cause’ of having committed the murder, which would have kept him locked up until trial or release.
But the court decided that the evidence was not sufficient, and only agreed to keep him on remand for a week, after which the prosecution will have to reapply to the court.
The prosecution confirmed that the man had had a relationship with the woman, but it is not known whether he was the father of the baby she was carrying.
“That’s a question for the forensic pathologists,” Holst said.
The woman was seven or eight months pregnant.
The man was questioned several times over the weekend, but denies any crime. He has previous convictions for violent crimes, and has been reported for assaulting a woman, although the case was never prosecuted.
Police have searched several properties over the weekend, but would not say what they found.