DRUG AND THERAPEUTICS BULLETIN (DTB), published by Which?, has discovered that unreliable advice has been given to pregnant women on the risks of fetal varicella syndrome. As a direct result, the Department of Health (DH) will now be changing its advice.

On discovering the unreliable information, DTB wrote to the DH, the Royal College of Obstetricians (RCOG) and the Health Protection Agency (HPA) alerting them to their incorrect advice on this condition in their current guidelines.

In reply, all three bodies have said they will be altering their advice.

Fetal varicella syndrome is an uncommon but potentially fatal condition that can affect the unborn child of a pregnant woman with chickenpox. It can cause problems such as skin loss or scarring, under-development or weakness of the limbs and low birth weight.

DTB recently published an article on Chickenpox, pregnancy and the newborn.1 This reported evidence indicating that the estimated risk of fetal varicella syndrome in children exposed to chickenpox in the uterus is around 0.5 per cent after infection in the mother at between two and 12 weeks of pregnancy; 1.4 per cent after infection at 12_28 weeks; and 0 per cent from 28 weeks onwards.

DTB found that these risks are at odds with current longstanding advice from the DH, RCOG and HPA.2_4 Guidelines from these bodies have suggested that the risk of fetal varicella syndrome is confined to maternal infection in the first 20 weeks of pregnancy.

The data reported in DTB comes from a recently published collation of evidence.5 Crucially, this collation includes a study that reported a case of fetal varicella syndrome following maternal infection at 24 weeks of pregnancy (out of a total of 157 women infected after 20 weeks).6 In addition, the collation included eight other published cases of fetal varicella syndrome where the mother was infected after the 20th week of pregnancy.7_14 There has also been a recently reported case of the syndrome having occurred after maternal infection in the 22nd week of pregnancy.15

According to DTB, this evidence calls into serious question suggestions that chickenpox infection after 20 weeks of pregnancy carries no risk of fetal varicella syndrome.

Dr Ike Iheanacho, editor, DTB, said:

?We are pleased that the DH and other bodies have accepted DTB's suggestion to revise their guidance on fetal varicella syndrome. Their advice will now reflect evidence that fetal varicella syndrome can occur following maternal chickenpox infection in the second half of pregnancy.?

For over 40 years DRUG AND THERAPEUTICS BULLETIN (DTB) has provided rigorous and independent evaluations of, and practical advice on, individual treatments and the management of disease for doctors, pharmacists and other healthcare professionals.

A monthly journal, DTB is published by Which?, the UK's major consumer organisation, and is unique in that it is wholly independent of industry, Government, regulatory authorities and the medical establishment and carries no advertising.

DTB also produces Treatment Notes - award-winning, evidence-based, practical information for patients that complements that available to healthcare professionals.

For further information about DTB and Treatment Notes or to subscribe, please go to http://www.dtb.org.uk

1. Chickenpox, pregnancy and the newborn. DTB 2005: 43; 9; 69_72

2. Department of Health, 2004. Varicella [online]. Available: gov.uk/assetRoot/04/07/31/40/04073140.pdf

3. Royal College of Obstetricians and Gynaecologists, 2001.Chickenpox in pregnancy [online]. Available: http//www.rcog.org.uk/resources/Public/pdf/Chickenpox_No13.pdf

4. Health Protection Agency. General Information - Chickenpox (Varicella) [online].Available: hpa.org.uk/infections/topics_az/chickenpox/gen_info.htm [Accessed 5 October 2005].

5. Tan M, Koren G. Chickenpox in pregnancy: Revisited. Reprod Toxicol 2005 Jun 22; [Epub ahead of print].

6. Harger et al. Frequency of congenital varicella syndrome in a prospective cohort of 347 pregnant women. Obstet Gynecol 2002; 100: 260_5.

7. Kerkering KW. Abnormal cry and intracranial calcifications: clues to the diagnosis of fetal varicella-zoster syndrome. J Perinatol 2001; 21: 131_5.

8. Deasy NP, Jarosz, Cox TCS, Hughes E. Congenital varicella syndrome: cranial MRI in a long-term survivor. Neuroradiology 1999; 41: 205_7.

9. Michie CA, Acolet D, Charlton R et al. Varicella-zoster contracted in the second trimester of pregnancy. Pediatr Infect Dis J 1992; 205; 1050_3.

10. Lambert SR, Taylor D, Kriss A, Holzel H, Heard S. Ocular manifestations of the congenital varicella syndrome. Arch Ophthalmol 1989; 107: 52_6.

11. Salzman MB, Sood SK. Congenital anomalies resulting from maternal varicella at 25 1/2 weeks of gestation. Pediatr Infect Dis J 1992; 11: 504_5.

12. Ong CL, Daniel ML. Antenatal diagnosis of a porencephalic cyst in congenital varicella-zoster virus infection. Pediatr Radiol 1998; 28: 94.

13. Forrest JM, Mego S, Burgess MA. Congenital and neonatal varicella in Australia. J Pediatr Child Health 2000; 36: 108_13.

14. Bai PVA, John TJ. Congenital skin ulcers following varicella in late pregnancy. J Pediatr 1979; 94: 65_7.

15. Boumahni B, Kauffmann E, Laffitte A, Randrianaivo H, Fourmaintraux A. Congenital varicella: limits of prenatal diagnosis. Arch Pediatr 2005; 12: 361_3.

Samantha Flack
Assistant Media Relations Officer
Which?, 2 Marylebone Road, London, NW1 4DF
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