Raymond Donnelly preyed on his victims over a period of 13 years. The 32-year-old raped one women shortly after she had given birth.
Donnelly was found guilty yesterday following a trial at the High Court in Glasgow. He was also convicted of separate assaults on the women - three of whom were pregnant at the time.
Donnelly had denied the allegations claiming the victims had "conspired" against him to make up lies.
Judge Alastair Stewart QC remanded him in custody and deferred sentencing until July.
The court heard how the incidents took place between 1997 and 2010 at addresses in Ayrshire. The women were subjected to "systematic violence" at the hands of Donnelly.
Paul Kearney, prosecuting, said he "controlled, intimidated, assaulted and raped each of them". Mr Kearney told the jury: "This man preyed upon and exploited the vulnerabilities of each woman.
"He sexually assaulted each of these young women to satisfy his desires and his own selfish interests with not a moment's consideration as to the hurt that he was causing."
One of the victims recalled how she was raped after she had given birth in December 2005.