The Thorntons' baby, Jessie, was born in March 1997, in perfect health and with no chromosomal abnormalities, but the couple's highly sophisticated, first-class medical care had turned the middle of Polly's pregnancy into a nightmare.
"When we went to that first scan, it was wonderful to see the baby move and to be shown the heart beat," Polly says. "But then the operator went quiet and fetched someone else. They both looked at the scan and looked grave. We asked whether there was a problem and they were evasive. We had to go back to the clinic and talk to a doctor.
"He told us that the baby's nuchal fold, which is the skin at the back of the baby's neck, was abnormally large and, as that could indicate a chromosomal abnormality, we would have to come back for another scan. Because we were going on holiday to Tunisia the next day, the doctors kindly arranged for a second one later that day. It was a clearer, state- of-the-art scan."
The new scan revealed, in greater detail, what the first one had suggested - that the nuchal fold was much larger than normal. Polly and Alan were told that the baby had a one in four chance of having Down's Syndrome. The senior doctor recommended that Polly undergo an amniocentesis (see box), which would provide a definitive diagnosis. That test could not be done until she was 15 and a half weeks pregnant, which meant waiting three weeks.
"It was devastating. It was only 12 days after the death of my mother. We went on holiday but we could not think about much else. We kept noticing children with Down's Syndrome everywhere. We didn't know what we would do if the amniocentesis was positive."
After the amniocentesis, the couple, who live in Lewisham, south London, had to wait another three weeks for the result. Much to their relief, it came back normal, but the saga did not end there. At her 20-week scan, Polly was told that an enlarged nuchal fold could also be a sign of a heart abnormality, so she was sent to Great Ormond Street Hospital for a heart scan. That turned out to be normal, but the doctor still recommended regular scans up to birth.
At 28 weeks, however, Polly, who is a writer and co-author of the book Downshifting: The Guide to Happier, Simpler Living, felt she had had enough. "I felt our medical care had been good and the doctors felt that they were acting in our best interests. But by this time I had had five scans and wanted to feel like a normal pregnant woman."
Polly's experience is far from unique and raises an important question. How can the process of offering women screening tests for foetal abnormality be organised to minimise the trauma and stress?
Ms Joanie Dimavicius, director of the charity Antenatal Results and Choices (ARC), does not believe that it is possible to run a system that does not raise anxiety. "Anxiety is part of the testing process," she says. "Once an ultrasound operator has seen something on a scan which is a variation of the norm, that information belongs to the woman. It would be wrong to simply put it in the notes and not tell her. Unfortunately a lot of the abnormalities are what are known as `soft markers' - they are associated with certain conditions but are not diagnostic of them. Many are of uncertain significance."
Ms Dimavicius believes that the main way of relieving stress to parents is by providing information and time to listen to their worries. Her charity provides a 24-hour helpline which people can ring.
The doctor who pioneered the measuring of the nuchal fold as a screening test is Professor Kyprianos Nicolaides, professor of foetal medicine at King's College Hospital, London. He still believes it is a useful test but now recommends that it is used in combination with two other measurements - the age of the mother and the presence of certain hormones in the blood. Taken together, these measurements provide a reliable indicator of which mothers should go on to have an amniocentesis test.
"This combination of tests will detect 90 per cent of babies with Down's Syndrome," Professor Nicolaides says. The majority (19 out of 20) of mothers who go on to have an amniocentesis in these circumstances will discover that they are expecting a normal child, but it considerably reduces the number of amniocenteses you have to do to pick up the vast majority of babies with Down's Syndrome, he explains.
Is there any way doctors can pick up chromosomal abnormalities without subjecting such a large number of women to an amniocentesis test? Professor Charles Rodeck, professor of obstetrics and gynaecology at the University College London Medical School, thinks so. The future may lie in combining the results of the 12-week ultrasound scan with the blood tests now done at 15 weeks (the triple test) to detect abnormalities. "That way you should get a good detection rate for abnormalities and a lower false positive rate. In other words, fewer women would have to go on to have an amniocentesis."
Professor Rodeck adds that "with new rapid chromosome analysis, it is now possible to get the results back from an amniocentesis in 48 hours, instead of the three weeks it used to take. Although rapid analysis cannot rule out every single chromosomal abnormality, it can eliminate the more common and more serious ones."
Polly Thornton thinks these developments will be useful steps forward. "The problem about being told that your child may have a serious abnormality and then not knowing for certain for many weeks is that you start instinctively denying your pregnancy just in case it never goes to term," she says. "All the weeks of uncertainty did not stop us bonding with our baby, but if it had gone on much longer, we would have been much less prepared for her birth."
Helen Statham, a senior research associate at the University of Cambridge's Centre for Family Research, says there is no way of avoiding the stress of tests. "The trouble is, most women have scans for reassurance. But any test that can reassure you also has the potential to alarm you. Otherwise it is meaningless."
a guide to antenatal tests
AN EARLY ultrasound scan at 10-12 weeks can reveal major abnormalities, such as anencephaly (absence of the brain) or missing limbs, and can show whether a foetus is at increased risk of Down's Syndrome. In Down's pregnancies the nuchal fold (the skin at the back of the baby's neck) is enlarged.
Biochemical blood tests at 15-18 weeks include one that measures Alpha- fetoprotein (AFP): high levels may indicate spina bifida, although nine out of 10 women with raised AFP levels are not carrying an abnormal foetus. The triple test (also called the Bart's test) measures AFP plus oestriol and human chorionic gonadotrophin: abnormal levels, taken together with the maternal age, give a risk factor for Down's syndrome. If blood tests indicate a high risk of abnormality, diagnostic tests such as amniocentesis will be offered.
A later ultrasound scan at 16-20 weeks can detect spina bifida, hare- lip and abnormalities of the intestines, diaphragm and limbs. How much is discovered during a scan depends on the operator's skill and also the baby's position.
Amniocentesis is offered to women who have had an abnormal triple test result, or whose early ultrasound showed an enlarged nuchal fold, or who are over 35 or 40, and therefore at greater risk of having a Down's baby. A fine needle is inserted through the wall of the abdomen into the womb to draw out amniotic fluid for analysis. Chorionic villus sampling (CVS), in which cells from the placenta are drawn off, can be performed at 10- 12 weeks, but there is a slightly higher risk of miscarriage than with amniocentesis.Reuse content