Pandemic Influenza: What Obstetricians Need to Know

Management of Infection for the Obstetrician/Gynecologist

Pregnant women have an increased morbidity and mortality for certain illnesses owing to the physiologic and immunologic changes in pregnancy. Certain infections are common during pregnancy, including urinary tract infections and pneumonia. Others are uncommon, but yield increased severity, including influenza. Human immunodeficiency virus, although it does not increase in pathogenesis during pregnancy, requires specific attention and management in the context of pregnancy.

Viral invasion of the amniotic cavity (VIAC) in the midtrimester of pregnancy

INTRODUCTION

The prevalence of viral infections in the amniotic fluid (AF) has not yet been ascertained. The aim of this study was to determine the prevalence of specific viral nucleic acids in the AF and its relationship to pregnancy outcome.

STUDY DESIGN

From a cohort of 847 consecutive women undergoing midtrimester amniocentesis, 729 cases were included in this study after exclusion of documented fetal anomalies, chromosomal abnormalities, unavailability of AF specimens and clinical outcomes. AF specimens were tested by quantitative real-time PCR for the presence of genome sequences of the following viruses: adenoviruses, herpes simplex virus (HSV), varicella zoster virus (VZV), human herpesvirus 6 (HHV6), human cytomegalovirus (HCMV), Epstein-Barr virus (EBV), parvovirus B19 and enteroviruses. Viral nucleic acid testing was also performed in maternal blood and cord blood in the population of women in whom AF was positive for viruses and in a control group of 29 women with AF negative for viral nucleic acids. The relationship between the presence of viruses and pregnancy and neonatal outcome was examined. The correlation between the presence of nucleic acids of viruses in the AF and the concentration of the cytokine interleukin-6 (IL-6) and the T cell chemokine CXCL-10 (or IP-10) in AF and maternal blood were analyzed.

RESULTS

Viral genome sequences were found in 16 of 729 (2.2%) AF samples. HHV6 was the most commonly detected virus (7 cases, 1.0%), followed by HCMV (6 cases, 0.8%), parvovirus B19 (2 cases, 0.3%) and EBV (1 case, 0.1%), while HSV, VZV, enteroviruses and adenoviruses were not found in this cohort. Corresponding viral DNA was also detected in maternal blood of six out of seven women with HHV6-positive AF and in the umbilical cord plasma, which was available in one case. In contrast, viral DNA was not detected in maternal blood of women with AF positive for parvovirus B19, HCMV, EBV or of women with AF negative for viruses. HHV6 genome copy number in AF and maternal blood was consistent with genomic integration of viral DNA and genetic infection in all women. There was no significant difference in the AF concentration of IL-6 and IP-10 between patients with and without VIAC. However, for HCMV, there was a significant relationship between viral copy number and IP-10 concentration in maternal blood and AF. The group of women with AF positive for viral DNA delivered at term healthy neonates without complications in 14 out of 16 cases. In one case of HHV6 infection in the AF, the patient developed gestational hypertension at term, and in another case of HHV6 infection in the AF, the patient delivered at 33 weeks after preterm premature rupture of membranes (PPROM).

CONCLUSION

Viral nucleic acids are detectable in 2.2% of AF samples obtained from asymptomatic women in the midtrimester. HHV6 was the most frequently detected virus in AF. Adenoviruses were not detected. Vertical transmission of HHV6 was demonstrated in one case.

Maternal and neonatal outcome of pregnant women infected with H1N1 influenza virus (swine flu)

OBJECTIVE

To investigate maternal and neonatal outcome of pregnant women infected with H1N1 influenza virus.

METHODS

We prospectively followed all pregnant women hospitalized with positive H1N1 influenza virus nasal polymerase chain reaction tests between September 2009 and April 2010. Maternal and neonatal complications were recorded.

RESULTS

Twenty-four women positive for H1N1 were hospitalized. Only 2 women suffered from asthma, all others had no co-morbidities. Most women were in the third trimester (14 women, 58%). Common presenting symptoms were dyspnea (83%) and Fever (79%). Eleven women (46%) had pneumonia/Adult Respiratory Distress syndrome (ARDS) on chest X-rays. Six women were actively delivered due to maternal or fetal distress. Gestational age at delivery for these women was significantly lower (34 weeks vs. 39 weeks, p = 0.005). Of women delivered, five were admitted to intensive care units (ICU), three needed mechanical ventilation, and one tracheostomy. Patients admitted to ICU had significantly higher white blood cell (WBC) and C-reactive protein (CRP) levels (p < 0.01, p < 0.01, respectively). The main neonatal complication was prematurity where delivery was indicated.

CONCLUSIONS

H1N1 flu pandemic has the potential of causing serious maternal morbidity during pregnancy. ARDS, elevated WBC and CRP levels correlate with more severe cases. Prematurity is associated with severity of maternal disease.

The use of high-frequency oscillatory ventilation in a patient with H1N1 pneumonia

A 32-year-old multigravida was admitted at 33.9 weeks with respiratory distress. Community-acquired pneumonia was suspected and antimicrobial treatment initiated with ceftriaxone sodium and azithromycin. However, despite these therapies her respiratory status deteriorated. She was subsequently diagnosed with Swine-origin Influenza A (H1N1) Virus pneumonia and treated with oseltamivir. After failing conventional ventilation, high-frequency oscillatory ventilation (HFOV) was utilized. In pregnant patients who fail to respond to conventional ventilation techniques, HFOV should be considered.