In Abigail O'Brien's vast multimedia project, she uses the seven sacraments to celebrate turning points in women's lives. It's a huge amount to think about, writes Aidan Dunne

It was a chance encounter with Nicolas Poussin's sequence of paintings on the seven sacraments at an exhibition in London's Royal Academy in 1995 that turned Abigail O'Brien's thoughts to the theme. Not, on the face of it, an obvious one for a contemporary female artist.

"No," she explains. "In many ways it was very unlikely. But it struck me that all the protagonists in the paintings were male, and that is typical of the subject." Women's roles are confined to doing menial things in the background. "I decided to try to do a female version, but also something celebratory, removed from the solemnity of the way it's traditionally treated."

She didn't quite anticipate that it would take her nine years to complete her own Seven Sacraments, a vast multi-media undertaking that is now gathered into one compendious exhibition. It is made up of many large-scale photographic prints, of carefully staged tableaux and documentary material, of sculptural pieces in several materials, and - a vital and consistent element - of sewing and needlework of various kinds.

The whole show was extremely well received at two German venues last year and has now opened at the Royal Hibernian Academy Gallagher Gallery. Overall, O'Brien's work retains something of Poussin's poised classicism. There is a consistent coolness about its aesthetic arising from the crisp, logical clarity of its exposition.

That said, it is a long way from being simply a reworking of the seven sacraments in any given form. Rather it's an open-ended, speculative work adhering loosely to its given conceptual framework. O'Brien feels free to range widely as she proceeds.

Broadly speaking, she uses the idea of the sacraments as ritualising decisive moments in women's lives. This allows her to delve into the way women live their lives within containing familial, cultural and religious frameworks.

A point of reference throughout the work is the biblical story of Christ in the house of Martha and Mary. It's most explicitly treated in O'Brien's version of the sacrament of confirmation, but it is implicit throughout. When Martha complains that she is doing all the work - all the practical work - while Mary sits and listens to Christ, he admonishes her and claims that Mary is actually performing the more important labour. Here the two women embody the duality, and the conflicting demands of the vita activa and the vita contemplativa (the theme is amplified in O'Brien's concurrent exhibition at the Rubicon Gallery).

For her, this problematic duality crystallises the competing demands made on every woman and, more often than not, the exclusive choice she is pressed to make. "There is that constant pull between the active and the contemplative. For example, you can see it reflected in the difficulties women face when it comes to being a mother and making a career outside of the domestic environment. Do you choose to do something for yourself? There is a level of guilt involved."

Marriage was the first sacrament O'Brien tackled. She did so in the pointedly titled The Last Supper, which draws directly on Leonardo's universally known masterpiece. There are 12 women in the carefully staged photographic tableaux. In front of the images a dining table is laid with just one place. "It's a woman's last meal with her friends before she gets married. So it's celebratory, but there is this feeling of her being poised on the edge of something unknown, of decisive change, so there is also something darker there, an ominous undertone that I think carries through all the work."

Chronologically, the next sacrament she addressed was baptism. A mother bathes her baby, evoking images of the Virgin and the infant Jesus, but the baby is female. A series of photographic still lifes itemise the paraphernalia of baptism, including all the traditional gifts, with an emphasis on the whiteness and cleanliness associated with babies.

"I wanted a sense of the whole fluffy, white thing. I was a mother myself at the time and I was interested in the whole retail therapy aspect of the experience, the kind of fetishising of babies with all this stuff."

There is, she points out, a difference between the ideal and the actual. "You feel this pressure that everything be perfect: perfect baby, perfect mother. You quickly realise that that is not the case. You're literally flying by the seat of your pants, trying desperately to control the chaos. The dream of perfection is shattered pretty quickly. But," she adds, "that's OK actually. It's good."

The baptismal dress is embellished with the disquieting motto Mea culpa, implying that the infant is being introduced to a tradition of inherited guilt, a legacy as corrosive as the salt heaped in a pram in one photograph.

"With this and with confession and communion, there is this preoccupation with what mothers pass on to daughters, I think. What they pass on for better or worse, for good or bad."

She stands back from specifying which might be which. "In terms of those relationships, I think you spend your whole life figuring that out. And most of the time it's OK." She felt that confession and communion were linked. "Well, I couldn't separate them in my mind."

They occupy the kitchen, a kitchen shared by herself, her mother and her daughter.

In various combinations, they are cooking, though there is a curiously pristine, antiseptic quality to the scenes. "It's strange how the kitchen has become this extraordinary thing. People spend thousands and thousands on making dream kitchens, but it often seems that the more you spend on a kitchen the less you actually use it. The communal meal used to be such a central focus of domestic life, and now it has become comparatively rare because of the kind of lives people lead. So often instead of being the heart of the home the kitchen has become this artificial, sterile place."

A monumentalised bread basket containing vast carved loaves celebrates the ritual of baking and eating. Formalised still life studies, largely inspired by those of the painter Juan Sanchez Cotan, give weighty consideration to the preparation of food.

"Ironically, when I was trying out different kinds of bread to use, I was baking every day and then telling my children they couldn't eat what I was making." Predictably enough, the most oppressive atmosphere greets you in The Ophelia Room, which gets its own distinct space. It is about extreme unction.

"I read an interpretation of Hamlet which suggested that Ophelia had no intention of killing herself, that her death was in fact accidental while she was in this distracted, distraught state." O'Brien made a series of embroidered samplers based on Ophelia's flower symbolism.

She also had in mind a pair of epistolary paintings by Gabriel Metsu, one of a man writing a letter, the other of a woman reading a letter. The general interpretation is of a letter between lovers.

"Then I heard an interview on the radio one evening with a woman who works in the dead letter room of a post office. Communication is vital, and I had this idea of the way there are misunderstandings, the ways we fail to communicate."

The grid of letters in a post office sorting office is reflected in the bureaucracy of death in a series of images of refrigerator doors in a morgue. There is a sense of rigid systems ill-equipped to accommodate human hesitancies and fallibility.

But, O'Brien suggests, some minor visual clues, plus the sound of a bell, indicate the persistence of the human spirit outside these fixed frameworks. "The Victorians tied bells to the fingers of corpses, in case they were not really dead."

For the sacrament of ordination she explores "a bishop's garden in Germany". For her, the meticulously clipped topiary of a formal garden indicates a desire for control that goes against the natural grain. "There was this story about the bishop and his mistress."

She also features an elderly Austrian woman in her own private, locked garden. "Where, as an older woman, do you go in society? She has made her own space, a fabulous garden."

Finally, that meeting of Martha and Mary, minus Christ. "We never quite figured out who was who," she says. Who, that is to say, is the active and who the contemplative protagonist. They are depicted against shelves lined with theoretical tomes. An Irish linen blanket is embroidered with a sequence of words that flow but do not make conventional sentences. "Really it denotes all the women in my life, drawing them all together in terms of how we have integrated with one another."

Not then, representations of the seven sacraments in any straightforward sense of the term. But there is a huge amount to think about in O'Brien's work. She is happy enough to be anything but categorical about how it might be interpreted.

"Really I've tried to keep things open. I know that as I went along I came up with a bundle of questions. I don't have the answers, but I'm happy to be left with the contradictions."

• The Seven Sacraments is at the RHA Gallagher Gallery until February 27th. Vita Activa is at the Rubicon Gallery until February 25th