A German woman who was abducted in Syria and held captive for nearly a year has revealed how her kidnappers were prepared to “cut off my head in front of a live camera”, but ended up pampering her with chocolate, toys and luxury nappies after she gave birth to a baby boy while in captivity.

The journalist Janina Findeisen, who was released with her child in September 2016, has spoken for the first time about the circumstances under which she travelled to a war zone on her own when seven months pregnant, and how she managed to survive the ordeal.

In an interview published in Süddeutsche Zeitung, Findeisen said she travelled to Syria in October 2015 in order to make a documentary about a schoolfriend who had turned to jihad and joined a faction of al-Qaida’s former affiliate in Syria, Jabhat al-Nusra.

Her pregnancy, she said, had spurred her on rather than made her more aware of the risks. “I felt pressured – precisely because of my pregnancy. I wanted to tell this one more story before only being able to pick up work a few months after the birth. I was not aware of the fact that in that moment I was making the biggest mistake of my life.”

Using a people smuggler in Antakya, southern Turkey, to drive her across the border into Syria, Findeisen said she had only shared her travel plans with the father of her child and not taken a mobile phone or a GPS tracker with her. While conceding that other people could have stopped her from going through with her plans, Findeisen said: “In the end it was my decision, and my mistake.”

Even though her school friend had promised her in an email that she would not be harmed, Findeisen and her driver were ambushed as they tried to cross over back into Turkey. The then 27-year-old was blindfolded at gunpoint and taken to a house in a remote location.

“On the first night I really believed that the security guarantee my friend had given me meant I would soon be released. But I soon realised that my hopes were in vain,” said Findeisen, whose book My Room in the House of War is being published in Germany next month. She said she does not believe that her friend was aware of the plan to kidnap her, though members of her group were.

Asked about treatment while in captivity, Findeisen said: “There were a couple of unpleasant situations, but I fared comparatively well. But nonetheless it was clear that these weren’t nice, humane people […] They would have cut off my head in front of a live camera.”

While she was held captive, the journalist kept a diary in tiny handwriting, using food packaging after she ran out of paper. She unsuccessfully tried to get the attention of people in neighbouring houses and secretly collected tools that could become handy to facilitate an escape.

“Until the end I believed that I would be back in Germany for the birth of my child,” Findeisen told her interviewers. “It was unimaginable to me that I would give birth to my child in Syria. I ignored the reality of the situation. Until I could ignore it no more.”

Her kidnappers blackmailed a doctor to deliver her child, and the birth took place without complications. “Suddenly everything was so very far away: the war, my kidnappers, it was just my son and I. He was so teeny, so fragile, but healthy.”

After the birth, Findeisen said, her kidnappers’ treatment of her changed: “With a small child I was even more helpless than before. When my son woke at night and screamed, they asked me the next morning what was wrong.” Her abductors brought her chocolate, multivitamin juice and a teddy bear, and did not spare expenses when it came to nappies: “In Syria there are two kinds of nappies: the one kind is known as ‘Assad nappies’ and are quite flimsy. Then there are Molfix, the premium nappy brand there. They brought me those.”

Asked if she thought that her son would one day reproach her for having him in such precarious circumstances, Findeisen said: “I have thought about that a lot. When the time comes, I will face up to it.”

Findeisen, who studied ethnology and comparative religion before researching modern jihadism as a journalist, was eventually freed – not by German intelligence services, but another group of Islamists. After hearing shots outside her compound, the journalist found herself surrounded by a group of men in balaclavas who told her they would take her back to Germany.

The group, Jabhat Fateh al-Sham, announced in an online statement that it had freed the German woman after a sharia court ruled her kidnapping un-Islamic in the light of the security guarantee given by her friend.

Findeisen told newspaper Süddeutsche Zeitung she believed this to have been the case, and that she was not aware of the German state having paid any of the €5m (£4.3m) ransom her kidnappers had demanded.

“I got a second chance,” Findeisen said. “Not everyone who got kidnapped [in Syria] was given one.”