Background
Methods
Data sources and searches
Study selection
Data extraction and methodological quality assessment
Data synthesis and analysis
Results
Overall results
Study | Outcome assesseda
| Pandemic or seasonal | Study Design | Methodology | Denominator calculation | Dates of surveillance | Lab Test | Country (WHO Region) b
| Country Income Level |
---|---|---|---|---|---|---|---|---|---|
Creanga 2010 | HA, ICU, D | Pandemic | Case series | Retrospective chart review: pregnant women hospitalized with confirmed H1N1 identified through “enhanced surveillance.” Testing performance only when requested by hospital. | Estimation using 2007 vital registration data (similar approach as in Jamieson et al.) | 05/01/2009–06/30/2009 | RT-PCR | US (PAHO) | High |
Doyle 2013 | SI, HA, ICU, D | Pandemic | Case series | Cases of pH1N1-confirmed acute respiratory illness reported by health providers to state of Florida | Florida birth registry data | 04/24/2009–05/31/2010 | RT-PCR or viral culture | US (PAHO) | High |
Griffiths 1980 | I | Seasonal | Cohort | Serological testing of women “booked” for antenatal care at one hospital in England during three years. Only women with postpartum specimens available were included. | Number of study participants | 05/1975–11/1975; 12/1975–06/1976; 08/1976–04/1977 | HI serology with 4-fold rise in antibody titer | UK (EURO) | High |
Hardy 1961 | I | Pandemic | Cohort | All pregnant women treated at Johns Hopkins Obstetrical Prenatal Clinic, with blood samples taken and questionnaires about symptoms administered monthly through delivery. Anyone with high HI titer was considered a case. | Number of study participants | 10/14/1957–02/01/1958 | Complement Complement fixation or HI test; no increase in titers required to be considered a case | US (PAHO) | High |
Irving 2000 | I | Seasonal | Cohort | Women delivering at two hospitals in Nottingham, England with available antenatal and postnatal sera. | Number of study participants | 05/1993–07/1994 | Single radial hemolysis and paired specimens for HI titer | UK (EURO) | High |
Jamieson 2009 | SI, HA, ICU, D | Pandemic | Case series | Pregnant women with confirmed or probable H1 infection reported by states to CDC as part of “enhanced” surveillance. | US Census bureau data | 04/15/2009–05/18/2009 | Confirmed: RT-PCR or viral culture+for H1. Probable: RT-PCR flu A+ but (−) for known subtypes | US (PAHO) | High |
Knight 2011 | ICU, D | Pandemic | Case series | Cases of H1 lab-confirmed ICU admission among pregnant women in Australia and New Zealand reported to Australian and New Zealand Intensive Care (ANZIC) study. Cases in UK reported to UK Obstetric Surveillance System. | National statistics on pregnancies combined with total birth data | AUS/NZ: 06/01/2009–08/31/2009 UK: 09/01/2009–01/31/2010 | Not stated in manuscript (but referenced) | Australia and New Zealand (WPRO) UK (EURO) | High |
Madhi 2014 | SI | Seasonal | Randomized Clinical trial | RCT of influenza vaccine efficacy. All participants with ILI or unknown respiratory illness were tested for influenza. | All women enrolled in placebo arm of study | 03/2011–08/2011; 03/2012–07/2012 | RT-PCR | South Africa (AFRO) | Upper-Middle |
Yates 2010c
| HA, ICU, D | Pandemic | Case series | Clinician-reported of H1-confirmed pregnant women admitted to 221/223 hospitals with consultant-led maternity units in the UK. Surveillance included zero-reporting and follow-up of reported cases. | Birth data from UK office for national statistics | 09/01/2009–01/31/2010 | Not specified | UK (EURO) | High |
Incidence of influenza virus infection
Study | Number of cases | Denominator | Crude incidence rate (CI) (aor derived from %) | 95% CI | Pandemic or seasonal? | Study design | Grading system and scoreb
| Hospital-basSummary of studies reporting repored or clinic-based? | Duration of surveillance (months or years) | Country |
---|---|---|---|---|---|---|---|---|---|---|
Griffiths 1980 | 77 | 1,595 | 483 per 10,000 pregnanciesa
| (399–614) | Seasonal | Cohort | NOS = 7 | Hospital | 3 years (22 months total influenza season) | UK |
Hardy 1961 | 61 | 671 | 909 per 10,000 pregnanciesa
| (716–1,155) | Pandemic | Cohort | NOS = 6 | Clinic | 5 months | US |
Irving 2000 | 182 | 1,659 | 1,097 per 10,000 pregnanciesa
| (957–1,258) | Seasonal | Cohort | NOS = 7 | Hospital | 15 months | UK |
Incidence of symptomatic influenza virus infection
Study | Number of cases | Denominator | Crude incidence rate (CI) | 95% CI | Pandemic or seasonal? | Study design | Grading system and scoreb
| Hospital-based or clinic-based? | Duration of surveillance (months or years) | Country |
---|---|---|---|---|---|---|---|---|---|---|
Doyle 2013 | 194 | 295,941 | 6.6 per 10,000 pregnanciesa
| (5.70–7.55) | Pandemic | Case series | NOS = 8 | Both | 13 months | US |
Jamieson 2009 | 34 | 3,392,060 | 0.10 per 10,000 pregnancies | (0.07–0.14) | Pandemic | Case series | JBI = 6/7 | Both | 1 month | US |
Madhi 2014 | HIV uninfected: 38 | 1,023 | 371 per 10,000 pregnanciesa
| (272–507) | Seasonal | Clinical trial | Low Risk (Cochrane) | Clinic | 2 years (9 months total influenza season) | South Africa |
HIV infected: 16 | 88 | 1,818 per 10,000 pregnanciesa
| (1,167–2,832) | |||||||
Total: 54 | 1,111 | 486 per 10,000 pregnanciesa
| (375–630) |
Incidence of influenza-associated hospital admissions
Study | Number of cases | Denominator | Crude incidence rate (CI) | 95% CI | Pandemic or seasonal? | Study design | Grading system and scoreb
| Hospital-based or clinic-based? | Duration of surveillance (months or years) | Country |
---|---|---|---|---|---|---|---|---|---|---|
Jamieson 2009 | 14 | 3,392,060 | 0.04 per 10,000 pregnancies | (0.02–0.07) | Pandemic | Case series | JBI = 6/7 | Both | 1 month | US |
Creanga 2010 | 63 | 113,877 | 5.5 per 10,000 pregnancies | (4.25–7.08) | Pandemic | Case series | JBI = 6/7 | Hospital | 2 months | US |
Yates 2010 | 241 | 314,135 | 7.7 per 10,000 pregnancies | (6.7–8.7) | Pandemic | Case series | NOS = 9 | Hospital | 5 months | UK |
Doyle 2013 | 170 | 295,941 | 5.7 per 10,000 pregnanciesa
| (4.94–6.68) | Pandemic | Case series | NOS = 8 | Both | 13 months | US |
Incidence of influenza-associated ICU admissions
Study | Number of cases | Denominator | Crude incidence rate (CI) | 95% CI | Pandemic or seasonal? | Study design | Grading system and scoreb
| Hospital-based or clinic-based? | Duration of surveillance (months or years) | Country |
---|---|---|---|---|---|---|---|---|---|---|
Jamieson 2009 | 3 | 3,392,060 | 0.01 per 10,000 pregnanciesa
| (0.00–0.03) | Pandemic | Case series | JBI = 6/7 | Both | 1 month | US |
Creanga 2010 | 8 | 113,877 | 0.70 per 10,000 pregnancies | (0.30–1.38) | Pandemic | Case series | JBI = 6/7 | Hospital | 2 months | US |
Doyle 2013 | 9 | 295,941 | 0.30 per 10,000 pregnanciesa
| (0.16–0.58) | Pandemic | Case series | NOS = 8 | Both | 13 months | US |
Knight 2011 | 59 | 86,449 | 6.8 per 10,000 pregnancies | (5.2–8.8) | Pandemic | Case series | JBI = 6/7 | Hospital | 3 months | Australia/New Zealand |
57 | 332,569 | 1.7 per 10,000 pregnancies | (1.3–2.2) | 5 months | UK | |||||
Peak: 51 | 193,796 | 2.6 per 10,000 pregnancies | (2.0–3.5) | 3 months | UK |
Study | Number of cases | Denominator | Crude incidence rate (CI) | 95% CI | Pandemic or seasonal? | Study design | Grading system and scoreb
| Hospital-based or clinic-based? | Inclusion criteria | Duration of surveillance (months or years) | Country |
---|---|---|---|---|---|---|---|---|---|---|---|
Jamieson 2009 | 1 | 3,392,060 | 0.003 per 10,000 pregnanciesa
| (0.000–0.021) | Pandemic | Case series | JBI = 6/7 | Both | Pregnant women with laboratory-confirmed (PCR or culture) H1N1 | 1 month | US |
Creanga 2010 | 2 | 113,877 | 0.18 per 10,000 pregnancies | (0.04–0.70) | Pandemic | Case series | JBI = 6/7 | Hospital | Reproductive-aged women with rtPCR-confirmed H1N1 hospitalized in NYC | 2 months | US |
Knight 2011 | 6 4 | 86,449 193,796 | 0.69 per 10,000 pregnancies 0.21 per 10,000 pregnanciesb
| (0.26–1.51) (0.06–0.53) | Pandemic | Case series | JBI = 6/7 | Hospital | Confirmed AH1N1v infection during pregnancy and subsequently admitted to ICU | 5 months 3 months | Australia/New Zealand UK |
Doyle 2013 | 8 | 295,941 | 0.27 per 10,000 pregnanciesa
| (0.14–0.54) | Pandemic | Case series | NOS = 8 | Both | Acute respiratory illness, with laboratory confirmation of pH1N1 by a certified laboratory | 13 months | US |