Influenza A H1N1 2009 (Swine Flu) and Pregnancy

Abstract

The Influenza A H1N1 pandemic (A H1N1) occurred between June 2009 and August 2010. Although the pandemic is now over, the virus has emerged as the predominant strain in the current seasonal influenza phase in the northern hemisphere. The A H1N1 influenza is a novel strain of the influenza A virus and is widely known as swine flu. The virus contains a mixture of genetic material from human, pig and bird flu virus. It is a new variety of flu which people have not had much immunity to. Much has been learnt from the Pandemic of 2009/2010 but the messages about vaccination and treatment seem to be taken slowly by the clinical profession. Most people affected by the virus, including pregnant women, suffer a mild viral illness, and make a full recovery. The median duration of illness is around seven days. This influenza typically affects the younger age group i.e. from the ages of 5-65 years. Current experience shows that the age group experiencing increased morbidity and mortality rates are in those under 65 years of age. Pregnant women, because of their altered immunity and physiological adaptations, are at higher risk of developing pulmonary complications, especially in the second and third trimesters. In the United Kingdom, twelve maternal deaths were reported to be associated with the H1N1 virus during the pandemic and clear avoidable factors were identified (Modder, Review of Maternal Deaths in the UK related to A H1N1 2009 influenza (CMACE). www.cmace.org.uk, 2010). The pregnancy outcomes were also poor for women who were affected by the virus with a fivefold increase in the perinatal mortality rate and threefold increase in the preterm delivery rate (Yates et al. Health Technol Assess 14(34):109-182, 2010). There continues to be a low uptake of the flu vaccine and commencement of antiviral treatment for pregnant women.

Maternal and Fetal Outcomes of Pregnancies Treated for H1N1 Virus Infection

“…The patients with at least one of the foolowing symptoms or signs were defined as severe H1N1 infection; persistant fever (>38 0 C) for at least 3 days, nausea, vomitting, diarrhea, dehydration, chest pain and productive coughing, (Table I, Table II (8,9) . Although the H1N1 influenza virus infection lasted 7 days in immunocompetent human, it was complicated with secondary viral or bacterial pneomonia in high risk groups (such as; health care professionals, patients with chronic illness, diabetics, morbid obese patients and pregnants) (1,8,10) .…”

“…Both the need for ICU and mortality rates were increased if the patients had dyspnea, tachpnea (>30/min), tachycardia, pneumonia, loss of conciousness and need oxygen supply during admission (1) . Studies reported that the rate of ICU requirement among pregnant women were between 7 to 9% (10,13) .…”

“…In our series one first trimester pregnancy was succesefully treated in ICU and she delivered at 35 weeks of pregnancy. Maternal mortality was common in pregnant women who are in third trimester, admitted to ICU and treated later than 2nd day of infection (1,3,11,15) .…”

“…Oseltamivir is used as per oral and zanamivir is used as inhaler. Although oseltamivir has been shown to cross the placenta and breast milk in small amounts, no adverse effects on the fetus or pregnancy have been recorded (1) . Treatment should be given within 48 hours after initial symptoms, neverthless the benefits of late treatment have been shown (11,17,18) .…”

“…Swine flu is a novel strain of the influenza A virus affecting humans and contains segments of genes from pig, bird and human influenza viruses (1) .…”