As a 21st-century feminist, of course I don’t believe a woman’s worth is determined by her ability to reproduce. Having a child isn’t the defining aspect of female identity – womanhood means so much more than motherhood. Yet I feel like a failure as a woman because I can’t have children. My own sense of self-worth is inextricably intertwined with my inability to get or stay pregnant.

The very definition of female is “of or denoting the sex that can bear offspring”. And I can’t do that. What’s the point of having ovaries, a womb and breasts if I can’t use them as nature intended? Getting my period is a monthly reminder of my reproductive potential – and failure. My uterus is defective, ergo I am defective.

The toxic legacy of infertility is that my identity has become binary: I am either infertile or I am a mother. Everything else has faded into the background, my sense of self-esteem superseded by my sense of inadequacy.

Surely this is ridiculous in 2018. After all, we’ve moved on from the days when a woman’s primary role was to produce children; when those who failed to do so were ostracised, their infertility perceived as a form of divine punishment.

Maybe not. In anguish at the shame of her infertility, the biblical matriarch Rachel is said to have cried: “Give me children or else I die!” In one study nearly 3,000 years later, half of the women seeking fertility treatment out of a sample of 200 couples said that infertility was the most upsetting experience of their lives. One study even found that levels of depression and anxiety in infertile patients were comparable with those in cancer patients.

My rational side knows that I don’t need a child to give my life purpose. So how have I become so utterly possessed by this fervent desire to become a mother – to the exclusion of all else? Am I a slave to biology? Is this maternal instinct a primal urge that I’m powerless to resist?

Surprisingly, it seems not. Research by Gary and Sandra Brase at Kansas State University has found that “baby fever” – a physical and emotional craving to have children – is a real phenomenon. But this desire to reproduce doesn’t appear to be innate.

In her book The Maternal Instinct, Professor Maria Vicedo-Castello reviewed the history of scientific views about maternal instinct and concluded that “there is no scientific evidence to claim that there is a maternal instinct that automatically gives women the desire to have children”. If we were biologically programmed to procreate, everyone would feel this longing – and lots of people don’t.

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Exactly why some women desire children and others don’t remains unclear, but it seems to be influenced by a combination of external factors rather than evolutionary instinct. The Brases found that being around babies appeared to have a profound impact for many women – setting off an emotional trigger that tells our brains that now would be a good time to have one of our own. Others have argued that baby fever is a learned desire, shaped by social and cultural expectations that are so deeply ingrained they feel innate.

Motherhood remains the cultural norm – just look at our vocabulary. “Parent” is the default status for an adult, while a non-parent is defined by the absence of children. In our pronatalist society, motherhood is frequently revered as the greatest of all life’s accomplishments – compare and contrast the pity for “poor Jennifer Aniston” and her empty womb with the hysteria (no pun intended) over Meghan and Harry’s pregnancy announcement.

The myth of the maternal instinct defines infertile women as failures for their inability to achieve this motherhood mandate, and pathologises women who are child-free by choice – because it does not allow for the notion that not wanting kids is just as natural as wanting them.

My grief is not because a life without children is inherently inferior, but because it’s the loss of a future that I deeply wanted, that represented happiness and belonging. This is a stereotype that my feminist self dismisses with contempt – but emotions that my infertile self can’t seem to rationalise away.

So I’ve decided that I’ve had enough of feeling guilty that I’m a crap feminist for buying into entrenched social norms; guilty that I’ve allowed my infertility to subsume every other aspect of my identity. It’s not my fault that my reproductive organs don’t work. And it’s not my fault that I feel such distress at an intangible and indefinite loss, for a child that never was – a disenfranchised grief for which no mourning rituals exist. I’m an infertile feminist, and I’m resolving to stop feeling conflicted over the grief I feel about that.

• Katy Lindemann is author of a forthcoming book that shares real women’s stories about the emotional experience of infertility and pregnancy loss