Having a baby is always a stressful time even if it usually results in the joy of a healthy new addition to the family. After months of caressing the 'bump' and imagining what the child will be like, the time of birth is the moment when the fantasy baby is replaced by the real child.

Every new parent goes through the moment of fear when they wonder if their child will be healthy, but the relief is often tempered with concern and possibly disappointment if a child is born with a 'port-wine stain' - a strawberry-purplish birthmark composed of small blood vessels. So, how does it happen?

Birthmarks are common - as many as one in ten newborns emerge with some form of birthmark. While some of these are almost unnoticeable marks that will either fade away quickly or else can be easily treated, other children are born with vascular birthmarks - congenital malformations of the blood supply under the skin that cause a large unsightly mark to appear.

A young boy with a large and disfiguring port-wine stain.

Doctors will often generally refer to unsightly vascular birthmarks as port-wine stains, but in fact there are a number of different kinds of marks, put into two main categories. Strawberry marks are a type of haemangioma, whereas port-wine stains are a form of vascular malformation. While haemangiomas can often resemble vascular malformations, they are not treated in the same way and it is always important for a newborn with a severe birthmark to be seen by a consultant dermatologist who can correctly diagnose the mark.

"About 0.1% of all births have a port-wine stain", says Dr Rosemary Watson, consultant dermatologist with Our Lady's Hospital for Sick Children in Crumlin, Dublin. "They can occur anywhere in the body, but are most commonly found on the face. This is also the most problematic place to treat them. The condition is caused by an abnormality of the blood flow at the area that can not be cured. Port-wine stains are a lifelong condition. They get progressively darker and thicker with age, so treatment is aimed at reducing the disfigurement".

Having a child with such a mark can put pressure on families. Parents often go through a grief process, initially shocked, then angry at why their child has received this mark and subsequently accepting the mark as part of a child they love. Some parents report feeling ashamed because they did not produce a perfect child. Others, believing pernicious old wive's tales, suffer a sense of guilt, as if somehow their actions could have caused the mark to occur.

The fact is that while birthmarks are often familial (people in families where there is a history of such marks are more likely to have them), there is no proven genetic cause or link. Researchers are exploring the possibility that some birthmarks are genetically predispositioned and are triggered by some kind of prenatal incident. However, such research is in its very early stages. Currently, no one really knows why a small proportion of children are born with such marks while others are not.

Port-wine stains rarely fade when children grow up. In fact, they often get worse. Laser treatment can be effective, but it will need to be repeated as time goes on.

Such marks are not life threatening, but nor are they benign. Depending on the location of the mark, a child might suffer complications including glaucoma, thickening of the skin, raised granulomas, enlarged lips and a loss of sensation in extremities. Then there are the psychological and social ramifications a child faces when they bear a large disfiguring mark.

Studies confirm what parents of children with port-wine stains will have already observed - children born with vascular marks are significantly more withdrawn and shy than their peers. They often walk with their head dropped and are usually uncomfortable in the company of children other than their siblings or close friends with whom they feel secure and accepted.

"People want to have normal looking children", said Dr Watson. "There is no doubt that other children can be very cruel to a child with a port-wine stain. For this reason, I believe that treatment should start as early as possible, definitely before school age. This is not possible in all cases of port-wine stain. While the vast majority of port-wine stains are congenital, there is a condition known as acquired port-wine stain, which occurs in adults, often after an injury. However, this is very rare".

In Ireland the laser treatment is available only at two centres - Our Lady's Hospital for Sick Children in Crumlin and St James's Hospital. Dr Watson describes the waiting list for treatment in Ireland as 'significant'. This is not only due to the lack of treatment centres, but also the practice in Ireland of giving very young children an anaesthetic before treatment. In America, a shortage of anaesthetists means they do not anaesthetise infants before laser treatment.

"We have excellent results in about 10% of cases, but the majority of patients can expect significant improvement", says Dr Watson. "We use a vascular pulse-dye laser, which has a long history of use in this kind of treatment and has a good safety record".

Other lasers may offer hope. At University College Hospital Galway plastic surgeons use a sclera laser for other procedures - a laser which has proven elsewhere to be effective on port-wine stains that resist pulse-dye laser treatment. However, the sclera laser is not used in Ireland for post-wine stains yet.

Most port-wine stains receive around six laser treatments, although this can rise to 12 depending on the size of their stain and its response to the laser. The vast majority of improvement occurs after the first three treatments. The face responds best to the laser treatment, limbs less so. Only 20% of those with stains on their legs can expect good results from laser treatment. The treatment does leave bruising in the area for around 10 days afterwards and there is a small risk of scarring. Unfortunately, there is no alternative to laser treatment at this time.

"When treating a port-wine stain, one has to consider its location and any potential medical implications", explains Dr Watson. "If the stain occurs around an eye, it can lead to glaucoma and on the head Sturge-Weber syndrome can sometimes develop, a neurological condition for which there is no known cause".

While the appearance of a port-wine stain on an infant is often disappointing for a parent, it can be very difficult for the child to deal with as he or she grows up. Laser treatment can only treat the surface appearance and will not remove the stain. As the child grows, more treatment may be required to reduce disfigurement and the mark must be monitored for potential complications such as glaucoma.

However, as parents grow to love and appreciate their child, the physical appearance of such a mark recedes into the background and becomes invisible to them and to others who know the child well. The biggest problem people with port-wine stains tend to face is staring from others and the ignorance of the general public.

As there is no known cause for such marks, it literally could have happened to anyone at birth. This is a point many people would do well to remember the next time someone with such a birthmark is in their company.