I was on the phone one evening, chatting to an acquaintance while I half-watched TV. I w as feeling quite relaxed and happy, exchanging news, including that my stepdaughter had recently had her first baby. "Now, what are you going to be called?" the friend said. "You're not his real grandma." Her words struck with force. "Here we go again," I thought. Of course, I could never be a real grandmother because I had never been a real mother. Thirty years had passed since I had given up on the idea of having children, but now came the familiar surge of anger and upset. Once again, my childlessness had become an issue.

I first realised I might have a problem conceiving when I was 18. I was at university and certainly not thinking of getting pregnant, but I was worried enough about my irregular periods to go to the doctor, who advised I should forget about it until I did want to start a family. This didn't happen until some years later, when my then husband and I wanted a child. We had met when we had summer holiday jobs in neighbouring restaurants; it was love at first sight and two years later we were married. We had moved to London, loved life there, and starting a family wasn't a high priority for us. It was just something we assumed we would get round to. But as is often the way, it did become a huge priority later - when it was clear that it wasn't going to happen.

Investigations established that the problem was with me. What seemed like years of treatment followed as non-conception took over our lives. After two or three years, both exhausted, mentally and physically, we made the decision not to proceed any further. After that, I found it hard to motivate myself to do anything. Carrying on at work required a major effort. I was extremely depressed, and our marriage lasted only a year or so longer than the treatment. When my husband left me for someone else, the pain was almost unbearable, but getting on with my life was made even more difficult when I heard that he and his new partner were to have a baby.

Then, four years later, I met Joe. The first time I set eyes on him he was with a little girl, holding her by the hand as they came out of a local shop. I fell in love at first sight again - but this time with two people. Ours has been a happy marriage: we argue, and laugh, a lot together. We talk; most importantly for me, we can talk about my inability to have children. Our relationship has always included his daughter. And while she and I have had some stormy times (partly because I tried to take on too much of the mothering of her, wanting her to be my child), we have enjoyed lots of good times too. I am grateful to have been able to share in looking after her and seeing her grow up into a strong-minded, open-hearted young woman whom I love very much.

As time passed and life progressed happily with Joe, I found myself changed by the feminist movement, and in particular by the idea that women need not be defined by whether they had children. In this context, my infertility seemed less of an issue. And while I have had times when I have been very sad not to have my own children, this has not been constantly painful and I thought I had come to accept it as well as I could. Now, at the age of 60, the birth of my stepdaughter's baby/my husband's grandson (for a while I wasn't sure how to describe him) has made me look anew at what being childless has meant and continues to mean for me and those around me.

I think most people would acknowledge that being infertile is a kind of bereavement, with a grief for the children who never were, but there are other areas of loss that are more difficult to express and almost harder to acknowledge. I can't share with my stepdaughter any memories of how I looked after my babies - whether they were breastfed, how I dealt with sleeping and teething, and so on. I have no wisdom of that kind to pass on as a grandparent. I have even been asked by one acquaintance, in relation to my grandson, "Are you able to do anything with him? It can't be easy when you haven't had your own" - as if I were some hopeless incompetent, unable to pick the baby up without hurting it. And, when you "haven't had your own", of course, you don't pass on your genetic heritage, which means that you are excluded in the most obvious way when the conversation turns, as it inevitably will, to whom the new baby resembles.

Neither has the loss been all mine. Those close to me have not always felt able to share with me, afraid of upsetting me. My own mother has said that she doesn't know how to talk to me about my infertility; she clearly succeeded where I have failed and this makes it a very uncomfortable area for us. In a sense, I, and they, have lost a part of my humanity.

This may sound an overdramatisation, but I have a renewed sensitivity to comments about women who cannot have children of their own. I had thought that attitudes might have changed after the revolution in thinking that was feminism and the advances in the treatment of infertility, but now I'm not so sure. I still hear people describing infertile women who are doing all they can to have a child as selfish, or trying to "go against nature".

A quick look at the news in one recent week had two stories about childless women, both shocking in their way. In one, an Italian woman and her husband murdered four of their neighbours, including a two-year-old child. According to reports, the woman had been unable to have children, and this was seen as a possible reason for her murderous actions. In the US, Senator Barbara Boxer (a mother and grandmother) suggested that Condoleezza Rice's childlessness impacted on her foreign policies - the implication being that she, unlike women who have had children, is a woman who could send other people's off to their deaths. Underlying both stories is the idea that childless women are inhuman.

I wonder if this is one of the reasons I have never met anyone whom I know is infertile since I had my infertility treatment all those years ago. There must be women like me - but I don't know any personally. I know people who don't have children, but I don't know anyone who is openly infertile. Of course, this may be a generational issue and younger women may be much more open about their situation but, since the birth of my grandson, I have looked up infertility on the web - something I could not have done 30 years ago - and, though I found lots of information, the main focus was on infertility as an "illness" and what sort of treatments are on offer. So I wonder how young women who are going through treament now will deal with failure.

Unexpectedly, revisiting my infertility in this way has enabled me to feel better about myself. I have accepted that I am not a "real" grandma, although my stepdaughter begs to differ. For a while I wanted to be just "Wendy", and while I can't help feeling slightly uncomfortable when I hear myself called Grandma, I am getting used to the idea. Perhaps it is not surprising that it has taken me a while to adjust. After all, I have never been called Mum. Sometimes I still find myself feeling a bit of a fraud. A few weeks ago I was showing a friend a photograph of my grandson and I paused, uncomfortable about how to describe my relationship to him. "Well, he's your grandson, isn't he, and you're his grandma?" she said, and although it didn't feel quite right, I was so pleased with what she had said.

Of course, it is impossible to know how much the feeling that I am not a "real" grandma comes from me and how much from other people, but I don't want to deny what I, and other women like me, are. I don't want to be pitied, patronised, or judged. I want for myself and others to acknowledge my, and their, loss, and to move on.

In the meantime, I am doing lots of the things that most grandmas would - bathing him, pushing him around in his buggy, buying lovely things for him, just holding him and seeing his face crease up into a smile. It is a pleasure I never thought I would have. And when we spend time together, the misgivings about how I should describe myself or how other people see me recede. He is just a beautiful baby. I am so proud of having him in my life, my grandson.

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