Severe Acute Respiratory Syndrome and pregnancy

Severe Acute Respiratory Syndrome (SARS) has already had an enormous impact on society and medical practice but presents special problems in pregnancy. The following comments are based on the experience of those in Hong Kong caring for patients with SARS in pregnancy of which there have been 10 at the time of writing in May 2003. The disease causes atypical pneumonia and some patients rapidly progress to adult respiratory distress syndrome. This results in significant hypoxia. It may be associated with miscarriage in early pregnancy (as occurred in four of the five Hong Kong patients admitted in early pregnancy), fetal distress, intrauterine growth restriction and intrauterine death. To minimise these fetal effects, attempts should be made to keep the maternal arterial saturation above 95%. If there is maternal desaturation, patients have to sit upright because of respiratory distress. Once patients require mechanical ventilation, they should lie on their left sides to maximise maternal uterine blood flow. The fetus should be monitored with cardiotocography and ultrasound for growth and Doppler blood flow studies. SARS may also lead to renal failure, disseminated intravascular coagulation and multi-organ failure. Maternal critical illness may lead to premature rupture of membranes or premature labour. Tepid sponging has been advocated to lower maternal pyrexia and the risk of preterm labour. SARS is a very contagious viral infection, transmitted through droplets and close contact. Health care workers are particularly at risk and must take appropriate infection control precautions. Pregnant women with SARS must be isolated from other antenatal and postnatal patients. Precautions against airborne infection such as using a N95 mask (equivalent or higher standard, i.e. N100) should be practised in the whole SARS ward. The viral load is sufficiently high to cause contamination. To avoid cross infection of other team members and antenatal patients, a small group of health care attendants should be designated to handle these patients. This group should be regularly monitored for symptoms and signs of infection. The risk of cross infection is particularly high at the time of vaginal or operative deliveries, especially when there is maternal viraemia. Additional protection against airborne cross infection is needed, using negative pressure air circulation. Because of the risk of additional bacterial infection, broad-spectrum antibiotics have been recommended for treatment (in pregnancy clarithromycin 500 mg twice daily plus coamoxiclav 375 mg thrice daily). Ribavarin has been advocated as an antiviral agent for patients who are very sick and/or rapidly deteriorating even though there is no good evidence of its efficacy in SARS. However, there are concerns about its use in early pregnancy. Ribavarin has caused limb reduction deformities when given to hamsters in a single dose of 2.5 mg/kg, on a weight basis one tenth of the 2400 mg daily dose recommended for humans with SARS. There are no human data for early pregnancy use. There have not been any fetal problems reported in the very few women given ribavarin in the second half of pregnancy. If it is thought necessary to give ribavarin during embryogenesis, women should be counselled about the advisability of termination of pregnancy. High dose steroids starting with pulsed methylprednisolone and tapering to low doses of oral prednisolone have also been advocated. Any possible adverse effect of this regime on the fetus might seem small by comparison to the potential maternal benefit. However, in the Hong Kong series, two deaths were in association with multidrug resistant Staphylococcus aureus (MRSA) septicaemia in women who had received high dose steroids. One death was due to progressive respiratory failure — ARDS, but the other was due to septicaemic shock. The resultant immune suppression from high dose steroids must be considered a factor. Even if the woman has been given high dose prednisolone, additional dexamethasone should be given if she is being delivered preterm because of the inadequate placental transfer of prednisolone. Extra steroid may be necessary at the time of delivery to prevent maternal Addisonian collapse. SARS is most likely to be due to a new coronavirus similar to those that cause influenza. Pregnant women appear to be particularly susceptible to epidemic viral pneumonia. For example, in New York, at the time of the Asian influenza epidemic of 1957, half of the maternal deaths were due to pneumonia. In addition, varicella pneumonia seems to be more common in pregnancy and to have a worse prognosis with higher mortality than in the non-pregnant state. Our own experience with SARS in Hong Kong is in keeping with the extra risk of pregnancy in viral illness. In the seven cases of SARS in pregnancy admitted to the Princess Margaret Hospital (the designated hospital for all pregnant SARS cases), two (28%) have died and four (57%) have been admitted to intensive care for assisted ventilation by contrast with mortality rates of 10% and ICU admission rates of 20% in the non-pregnant population.