Ultra-sound screens are kind of like Rorschach Inkblots. You can see anything and nothing in them, unless trained in the peculiar topography of their green, glowing landscapes. As the nurse moved the sensor about my wife's abdomen at our first checkup, I peered at the blotches and lines, unable to make out very much at all. However, it was clear from the medic's concerned expression that something was wrong. One of the babies, it seemed, was significantly smaller than the other. This, we were told, could simply be a difficulty in the twinning process, or it could be something more serious.

We were sent to Dublin to see a specialist.

Just such a specialist probably told Miss D that her baby was not developing properly. The baby at the centre of the furore is suffering from a condition called anencephaly. Anencephaly is linked to other disorders such as spina bifida and hydrocephalus, but it is much more severe than either. Children with anencephaly do not develop fully functional brains. Often, the frontal lobe is missing, and the skull usually does not close properly, leaving brain matter exposed. The medical texts inform us that these children do not feel, think, see or hear. They are, effectively, vegetables.

We visited Temple Street, and met with the doctors there. The first thing we were told was that the twins were identical . . . they shared an amniotic sac. They were also both female. The doctor pointed out a kind of lumpy mass at the smaller twin's stomach, and told us that this was an umbilical hernia, meaning that many of her internal organs were on the outside. There were other signs, too, such as the shape of the head, and the feet.

What it amounted to was that our little girl had one of two rare genetic disorders: Trisomy 23 or Trisomy 18 . . .

Patau's Syndrome or Edward's Syndrome. Both Deirdre and I had worked with children with disabilities, but we had never heard of either of these conditions.

"What does that mean?" Deirdre asked. "Will she be intellectually disabled?"

"I'm afraid, " the doctor said gently, "Twin 2 is not compatible with life, and will probably die very shortly after birth."

We named them that evening. The larger twin was Marnie, the smaller Lucy. It seemed that, if our time with Lucy was to be so short, we had better make the best of it, build up as strong a relationship as we could.

A leaflet given to us by an understanding nurse contained accounts from parents who had been through similar experiences, and when we realised that such stories and information were available, we sought out more. The internet put us in touch with a whole range of support groups.

And what surprised us more than anything was the realisation that some of these children survive . . . for varying periods of time, certainly, but death was not as inevitably instantaneous as we had been told. All of a sudden we were seeing photographs, taken by parents, of the most beautiful children, hearing stories of families who, through sheer force of will and the strength of their love, kept their children alive.

Anencephaly is a more severe condition than either Edward's or Patau's.

The vast majority of children with anencephaly do die shortly after birth.

But some live for days, weeks, and a rare few for months.

Despite what the medics are saying, babies with anencephaly cry, respond to visual and auditory stimuli, and seem to revel in the contact with their family members during whatever amount of time is granted them.

Lucy died shortly before she was due to be born. She was delivered along with her sister on 27 November. She was tiny, and had a peaceful expression on her face. A smaller, mirror image of Marnie, she was simply lovely.

Marnie is a constant joy, but there are times, particularly family gettogethers or landmark events when we pause and wonder what it would be like with two. Sometimes, I can almost see the shadow of a slightly more petite, quieter, darker-eyed little girl walking beside my boisterous, strong-willed daughter . . . physically like Marnie, perhaps more like her older brother in personality.

Judges and lawyers will decide whether or not Miss D can travel to have the abortion she feels she wants.

I just want her to know that, while Marnie and Lucy's birth was tinged with so much pain, we wouldn't have missed it for the world.

Shane Dunphy is a child protection worker and lecturer, and the author of 'Last Ditch House'