div class=”ChapterContextInformation”>
14. Swine Flu and Pregnancy
14.1 H1N1/Swine Flu
The worldwide pandemic of swine flu (H1N1) was identified in Mexico in April 2009 and then spread to other parts of world [1]. The pandemic started in India in August 2009, and the index case was reported from Pune. It is referred to as the novel H1N1 influenza A infection, a term that reflects the unique genetic makeup of the virus. The new virus that emerged spread among people who hadn’t been near pigs. It was as a result of reassortment (genetic shift) of several swine strains, a human strain, and an avian strain limiting the ability of the immune system to recognize and destroy the new virus giving rise to a pandemic-like situation [2].
It is like seasonal flu, but it can cause more serious health problems for some people like children, elderly, pregnant women, and immunocompromised individuals. Mode of spread is through droplet like any other flu. Patients are infective since 1 day before they have any symptoms till as many as 7 days after they get symptoms. Children can be contagious for as long as 10 days.
The signs and symptoms range from mild infection, afebrile illness to severe complicated pneumonia. They include fever, headache, cough, body aches, sore throat, nasal stuffiness, and gastrointestinal symptoms like vomiting and diarrhea [1]. Signs of severe infection include tachypnea (RR > 30), hypoxia (SpO2 < 92%), chest pain on breathing, tachycardia (HR > 100), rigors, shock, dehydration and shock, purulent or blood-stained sputum, altered consciousness, or fever [3]. Severe infection warrants hospitalization and sometimes intensive care unit admission [3].
14.2 Pregnancy and Swine Flu
Pregnancy does not predispose women of acquiring influenza infection, but epidemiological studies show that the pregnant women have increased mortality and morbidity to influenza infection. Pregnant women have higher rate of hospital admission, requirement of mechanical ventilation, and higher mortality rate (up to seven times) especially in third trimester [4–7]. In a report by CDC, among 347 severely ill pregnant women, 75 died from 2009 H1N1, and 272 were admitted to an intensive care unit (ICU) and survived. Most of the women who died (62%) had an underlying medical condition like asthma, gestational diabetes, obesity, immune suppression, chronic lung, autoimmune diseases, etc. [8]
Increased fetal morbidity and mortality is also reported during both seasonal and pandemic influenza outbreaks. According to the CDC Pregnancy Flu Line surveillance data 2009, of the 168 pregnancy outcomes, 148 (88%) were live births, 11 (7%) were spontaneous abortions, 7 (4%) were fetal deaths, 1 was an ectopic pregnancy, 1 was a 15-week elective abortion secondary to intrauterine growth restriction live births, 63.6% were born preterm or very preterm, 4.1% were small for gestational age, 43.8% had low birth weight, 69.4% were admitted to the neonatal intensive care unit, and 29.2% had a low 5-minute Apgar score [8]. Changes in the immune, cardiac, and respiratory systems during pregnancy are responsible for increased severity of influenza infection [9].
Pregnancy-related complications of novel H1N1 infection are related to high-grade fever. These include nonreassuring fetal heart rate, fetal tachycardia, febrile morbidity, spontaneous abortions, premature rupture of membranes, neonatal seizures, and intrauterine death [10].
14.3 Diagnosis
Samples for testing include throat and deep nose swabs, nasopharyngeal aspirates, tracheal aspirates, bronchoalveolar lavage (BAL), and sputum. A rapid influenza antigen test is used, but confirmation is done once the reverse transcription polymerase chain reaction (RT-PCR) or a culture is positive [11]. However for suspected patients (probable case), treatment should not be delayed pending the reports.
14.4 General Preventive Precautions
Hygiene is the key to prevent flu in pregnancy. Pregnant women should not travel to places endemic to influenza and should avoid crowded places. The general steps recommended to prevent infection are handwashing; avoiding contact with infected person; cough etiquette and hand hygiene; avoid touching the eyes, nose, and mouth; and carry alcohol-based hand rub [12]. Education of the pregnant woman and staff during the influenza season is recommended. The women should be made aware of the early signs and symptoms and importance of early access to medical care.
Symptomatic patients should be placed on droplet precautions (including gowns, gloves, and N95 respirators). Fever should be treated immediately, and the drug of choice is acetaminophen.
Staff should be trained to isolate individuals with potential influenza infection, and during periods of increased community influenza activity, facilities should consider setting up triage stations that facilitate rapid screening of patients for symptoms of influenza and separation from other patients [13]. No special precautions are needed in disposal of waste or linen.
14.5 Antiviral Drugs in Influenza
Early institution of prevention and treatment with antiviral agents is associated with improved outcomes for pregnant women. Oseltamivir (Tamiflu) is the most common antiviral drug used for prophylaxis and treatment of influenza in pregnancy. The mechanism of action is the competitive inhibition of the neuraminidase enzyme of the virus that acts on the sialic acid residues of the host cells [14]. The treatment should be initiated as soon as possible ideally within 48 h. Decisions to start antiviral treatment should not wait for laboratory confirmation of influenza because it delays treatment, and a negative rapid influenza diagnostic test result does not rule out influenza. Antiviral medications are approximately 70–90% effective in preventing influenza and are useful adjuncts to influenza vaccination. The recommended dose for prevention is 75 mg daily for 7 days, and in exposed individuals it reduces the rate of infection by 70–90% [15]. The recommended dose for treatment is 75 mg twice daily for 5 days. In a study, the percentage of pregnant women with severe illness increased significantly from 3% when the drug was given within 48 h to 44% once the drug was given more than 5 days after symptom onset [16]. Hospitalized patients with severe infections (such as those with prolonged infection or who require intensive care unit admission) might require longer treatment courses. Some experts have even advocated the use of increased (doubled) doses of oseltamivir for some severely ill patients, but limited data suggest that higher dosing may not provide additional clinical benefit.
Another drug zanamivir is an inhalational drug and has lesser effect on fetus as it does not cross the placenta. Antiviral drugs are not a cure, but can shorten the illness and reduce the risk of complications, hasten recovery, and minimize chances of severe illness and hospitalization [17, 18].
Antiviral medication for H1N1 in pregnancy
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
