It was a Saturday morning and I was with Wendy, my friend from a previous high school. Like me, Wendy had left school in year 10. I hadn't seen much of her, but she'd phoned me a few weeks before out of the blue and suggested we go and see Sister Maureen, our old maths teacher, who'd left the order to marry a widower with five children. We didn't have to call her Sister Maureen any more, Wendy said when we were on our way. Now we could just call her Maureen.

I wanted very much to see Sister Maureen, who was from my old life. I was feeling so afraid. During the week, I had taken a specimen of urine to a pharmacist. Three days, the pharmacist said. Saturday was the third day. I asked Wendy to stop so I could make a call. I didn't say who I was calling. I rang the pharmacist. He said, "Congratulations, you're going to have a baby.

The light was soft, as it often is in autumn in Queensland. The sun had started on its journey away from us and even the Pacific Highway, one of the ugliest roads on earth, looked at ease, ready to receive us. I lay down outside the phone booth on the hard brown grass next to the highway, staring up at the blue sky.

It was as if my body knew something my mind did not.

Wendy wanted to know what was wrong.

"Someone died," I told her.

"Were you close?" she said. "I don't know."

We visited Maureen but I couldn't get my head around her name. I kept calling her Sister: yes, Sister; thank you, Sister; no thank you, Sister. She laughed when I did this. She mothered five children now; she was no longer Sister. She had such a lovely laugh. Sister Maureen served tinned asparagus, which I'd never eaten. I've never forgotten the taste. Sister Maureen beamed at us and said, "Look at you, you grand girls. I always knew you'd make good."

I had turned 18 just a few months before. My colleagues at The Telegraph, where I'd just started my cadetship, had bought a cake and sang – even the formidable Women's News editor, Miss Erica Parker. I was 18, an adult. I had been feeling so grown-up. But now I was feeling very small.

My teacher and her husband guessed. They forced it out of me one night the following week when I was at their house. I had said that I might leave my job as a cadet journalist – I couldn't think what else I'd do – and they wanted to know why. I was in a big lounge chair curled up small and they leaned over me, one on either side, and demanded to know what was going on, demanded that I speak. 

I was shaking all over, wanting to disappear. The shame I felt. This was all my fault, I was sure. The beach, the night I drank too much. We did the naughty but nice things, as he called them. I burst into tears and told them. I sobbed and sobbed and sobbed.

This was all my fault, I was sure. The beach, the night I drank too much. We did the naughty but nice things, as he called them … I sobbed and sobbed. 

They told me not to worry. They would fix it. The next day, my teacher's husband contacted a priest, an ex-army chaplain in Melbourne, who knew of a home for girls where I could stay. We agreed I should go away. Melbourne was a city they knew I'd never seen. My teacher and her husband told me it would be an adventure. They would come down for the birth, they said. They would visit me and everything would be all right.

Over the next week, I told everyone I was going to leave my job as a journalist. I was casual in the saying of it. I said I wanted to travel. This was shocking to my parents, to Miss Parker. I had been one of four successful applicants for cadetships from among more than 400 who applied, she said. How could I throw that away?

My teacher and her husband talked, but I was not included. My teacher was unwell, an unspecified unwellness later diagnosed as endometriosis. They had no children. My teacher's husband called them brats, said he didn't want to end up like his siblings who had brats. He told me I had upset my teacher. I felt bad for what I'd done, what I'd done to my teacher. She wasn't harsh with me, but I was sure she blamed me. I blamed myself. It was all my fault and I had to make it right. We agreed it would be best to keep my pregnancy a secret from everyone but my family.

We also agreed that while I should tell my parents I was pregnant, I shouldn't tell them my teacher's husband was the father. If people knew, the scandal would cost him his commission as an army officer.

My mother had guessed about the pregnancy as soon as I announced I was going to quit the job I loved so much. More to the point, first thing every morning I vomited. When I told her the father was a journalist I met at a party, she went very quiet and looked hard at me. "I was drunk," I said, "and I don't know his name." I closed my mouth and set it tight. I would not say more.

My father pushed until my mother turned to him and said, "That's enough, Mac." Strangely, of all the things I later worried about, this was the worst: that I agreed to tell my mother that I had became pregnant while I was drunk, having sex with a man whose name I couldn't remember. 

My parents would have been happy for me to stay in Brisbane instead of going away to Melbourne. We were not a family that had the luxury of caring much about its reputation, and Catholic Church rules were the least of our failures of social expectations. My father's family's Catholicism was two generations back. "You don't have to go away on our account," Mum said. "Only if you'll feel better." She looked at me again. I thought she might be going to say more but she didn't.

By this time – the late 1970s – the Catholic Church had already started to change anyway, to modernise. Girls who got pregnant were not wicked in those days: they were stupid. There was good contraception, family planning clinics. We were not bad, except in the eyes of one or two old ladies and the conservative end of the Church, which was losing ground.

Of course I had to go away. My teacher and her husband had said if anyone knew about the pregnancy, he would be in trouble. Other people didn't understand. Of course I had to go away.

Before I left The Telegraph, I told Miss Parker I was pregnant. She had been miffed when I gave her my letter of resignation, citing no reason other than a desire to travel, so I told her the story I'd told my parents. She was annoyed with me all over again. "That was stupid," she said. "Very stupid. You are a little fool."

She meant getting pregnant. She meant throwing away my career, because she could see, as I couldn't, that I would not get it back. She wanted to know who the journalist was, the father. I said I didn't know.

Even if she called me a fool, Miss Parker understood my leaving. The world was starting to change, but leaving was what girls had done for years in Brisbane. She asked if she could tell the editor of the paper. I said she couldn't. I was worried for my teacher and her husband. The more people who knew, the more likely he'd be in trouble.

Miss Parker shook her head, called me a fool again, and said to come back when it was over and she'd see what she could do.

My father wanted us to have a conversation about abortion. I'd resigned and was about to leave for Melbourne. Dad had been asking why I couldn't tell them the journalist's name, why I didn't remember. "Shouldn't we find him?" Dad said to me, to Mum.

"I do not want to find him, no," I said.

Dad said to Mum then, in my hearing, "I don't see why she can't just look after it." At first, I thought he meant the baby; look after the baby. I was silent.

Mum said, "Mac, she can't do that."

When I realised he meant have an abortion, not keep a baby, I left the room in tears, not because of any regard for the child growing inside me, but because I had been to the seminars at school run by Right to Life. They turned out the lights in the concert hall at my previous high school, so we 100 or so schoolgirls could see properly. They showed us the slides they brought with them in their carousel, the tiny perfect feet between a finger and thumb proving categorically that life begins at conception; the burgeoning foetus at time of termination. They told us about the different methods used and how much pain the baby felt. The suction method, the saltwater death, the poisons. I knew it to be murder. I would never have an abortion, I told my father.

But a year later, when I became pregnant again, I had an abortion without hesitation

I left Brisbane after I finished up at The Telegraph and drove my car to Melbourne with my oldest brother, Ian. Crossing the border from NSW to Victoria at 3am, I was spooked by big gums hanging over both sides of the highway at Echuca. I was as far from home as I'd ever been.

Ian was asleep on the back seat and I couldn't rouse him no matter how hard I tried. I longed for a human voice, so I turned on the radio and listened to country music. It was Johnny Cash, The Long Black Veil, which made me laugh. At dawn, we had apple pie and cream and icecream for breakfast at a truck stop Ian knew from another trip.

At 11 o'clock that morning, Ian left me at St Joseph's Convent in Grattan Street, Carlton. He was going to stay with friends and then hitch a ride home to Brisbane. I remember I didn't want him to go; I stalled him with small talk at the gate, became close to desperate as he became keener to extract himself. Finally, he said he must go and off he went.

I waited a few moments more and then went up the path to the door and rang the bell. It was answered by a nervous-looking nun who took me into a parlour and said she'd get Sister Mary, who was in charge of the girls. The first nun made me a cup of tea. There were lemon crisp biscuits. I took two. She watched me eat them. I worried about the crumbs. 

In Melbourne during that time, someone who caught the tram from the city and alighted at the corner of Swanston and Grattan streets would pass the Royal Women's Hospital across Swanston on their left. They would cross another street and then walk a little way further to 99 Grattan, which would be followed by 103, a double terrace, St Joseph's Convent. That was the door I was told to knock on. There was no 101 Grattan Street.

But for years, 101 Grattan Street was where I thought I'd lived. It's where people addressed their letters to us girls. The nuns – whose terrace covered a double block – gave us that address so that there would be no real address if someone came searching for one of the girls. The postman knew the letters were to go to the convent at 103.

I only learnt this years later, when I went back to Grattan Street with my husband, David, trying to understand something of what had happened, what I'd done. I went looking for the place I'd been and found it had never existed.

In the home, I had my own room with its own sink. I met the other girls, one of whom became my good friend. Jill was a nurse and the father of her baby was an apprentice from her home town in northern Victoria. He was young, like us. I told Jill the father of my baby was a boy I knew at university, also young like us. The father of Jill's baby came to visit Jill each month. They were going to be married one day, Jill told me, but not yet. Same with me, I said.

Jill and I sat up late smoking cigarettes and drinking coffee. As our bellies swelled, we didn't talk about babies. We talked about what we'd do when we got out. We talked about the other girls. There was a girl we hated, Paula, who came back at the end of September, after her baby was born, much changed

Paula was a chatterbox, never shut up – it was what we criticised in her – but when she came back to pack up after her baby was born, she had little to say. If this unnerved us, we never spoke of it. Later we heard she changed her mind and came back a second time, within the 30 days, and took her baby home. Typical, Jill and I would have said, if we had said anything. Paula was weak.

Another girl, Jane, wasn't booked into the Royal Women's Hospital like the rest of us. She was a patient at the private Catholic Mercy Hospital. I think her people were unhappy about what she'd done. No one visited her.

Lily was a prostitute, pregnant for the second time, giving up a second baby. She'd had polio as a child and walked with sticks. When she was with us, we walked slowly. She said she didn't know if she would give up this baby.

I didn't feel self-conscious or guilty, not then. If I felt bad, it was for what I'd done to my teacher. I was young enough to believe I was on an adventure, like my teacher and her husband said. My only cause for shame was what I'd done to them, what I'd done to my teacher. I felt it was all my fault.

As my belly swelled, I began to see it as a lump, an inconvenience, that stopped me sleeping. Not as anything else. I never looked at books with pictures of babies in them. I didn't notice if ever I happened upon a woman with a baby in the street. I didn't see women with babies at the hospital when I went for appointments.

Sister Mary told us an occupational therapist would be coming to see us on Thursday mornings. She was blonde, the occupational therapist, and worked hard to act as if we were normal. She smiled and trained her eyes on our faces, ignoring our bellies. In one of the first sessions, I said, "Are we going to do basket weaving?" She told me I could leave if I wanted to, so I did. I went and hung around Sister Margaret in the kitchen.

Sister Margaret was the cook at St Joseph's. She cooked for the nuns and for us. "The same food," she told me. "I cook the same food for you as I do for us. I don't let them do the other." She didn't tell me what "the other" was. I think it was that the nuns would eat different food from the girls; the girls ate poorer-quality food. At St Joseph's, before my time, girls were made to work. The nuns took in linen and the girls washed it and wrung it out to earn their keep while they waited for their babies to be born. They were treated as unforgiven sinners. That was why their food was different from the nuns' food.

Their sin was not that they were going to give up a baby. Their sin was the sex that made the baby. Giving up the baby, sending the baby to a good home with two Catholic parents, was what redeemed them, got them out of the home where they were sinners unforgiven.

The memory of these beliefs was still fresh when I was in Melbourne. There were still nuns living in the convent who took this view, including Sister Mary. She liked me, because I was intelligent and read books. I think she might have found my behaviour hard to square away with who I was, would have preferred, I think, sinful girls to be unintelligent.

I liked Sister Margaret best. She was tall and large-boned, in her 50s when I met her, the youngest of 12 children. She had a red face, as if her heart was about to let her down, or she'd just come in from a windy walk along a headland. She added so much salt to our food that sometimes it was hard to eat. "I have to cook it to someone's taste," she said, "so I cook it to mine."

I kept a coffee mug she gave me, beige Dunoon porcelain with brown sheep embossed on it. I've tried to throw it out several times, but it keeps getting out of the bin and up onto the sink, so I've given up.

I was living on sickness benefit, the only support available to pregnant women. I bought vitamin E because my teacher and her husband told me to take it for my skin, so I didn't get stretch marks. I got them anyway, long red welts across my breasts and down my belly. I bought cigarettes and toiletries. I shopped at King & Godfree.

I went to Mass at South Melbourne, the parish of the priest who'd found the home for me. His name was Father Bob and my teacher's husband knew him because he'd been an army chaplain. My teacher's husband rang him on my behalf and told him that one of his wife's students, a nice girl, had got herself in trouble and could Father Bob help. 

My teacher's husband told me this, that he had described me as a "nice" girl. It was a joke. I was not a "nice" girl, we all knew, because I was already in trouble at school before my teacher and her husband met me. They'd helped me get out of trouble. I was lucky they'd done this. This was what I believed. It's what they told me.

Edited extract from For a Girl: A True Story of Secrets, Motherhood and Hope, by Mary-Rose MacColl (Allen & Unwin), out now.

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