tetano
Editor, Senior Moderator
Int J Infect Dis
. 2026 Nov 11:109228.
doi: 10.1016/j.ijid.2026.109228. Online ahead of print.
Rui Wang 1 , Jinghui Sun 1 , Jianyang Wang 2 , Yuanyuan Zhang 1 , Cheng Liu 1 , Wanting Hong 3 , Ningning Du 4 , Shuai Shao 4 , Liling Chen 5
Affiliations Expand
Background: Physiological and immunological changes render pregnant women susceptible to influenza, leading to increased risks of severe illness and adverse pregnancy outcomes. These outcomes are major causes of perinatal mortality and morbidity, and fetal deaths (including miscarriage and stillbirth) pose a major public health challenge. However, population-based cohort studies on this topic, particularly from China, remain scarce. Therefore, clarifying the association between influenza infection and adverse pregnancy outcomes is critical for optimizing antenatal care and reducing maternal-neonatal risks.
Methods: We conducted a population-based matched cohort study among pregnant women in Suzhou, China, from October 2018 to September 2024, based on active surveillance of influenza-related acute respiratory or febrile illness (ARFI) hospitalizations. Exposed groups were RT-PCR-confirmed influenza infections among hospitalized ARFI pregnant women, excluding those with delivery outside Jiangsu Province, miscarriage or stillbirth in the current pregnancy, repeated ARFI-related hospitalizations during the same pregnancy, multiple gestations, or already postpartum at ARFI admission. Unexposed groups were selected from the same source population, matched 1:4 by age, last menstrual period, gravidity, and parity, excluding those with any ARFI hospitalization, delivery outside Jiangsu Province, miscarriage or stillbirth in the current pregnancy, or multiple gestation. For preterm birth analysis, we included only exposed women with gestational age 28-37 weeks and their matched controls. For term outcomes (macrosomia, term low birth weight (TLBW), small for gestational age (SGA), large for gestational age (LGA), high-risk infants, frail infants, 1-min Apgar < 7, and neonatal resuscitation), we excluded preterm births and their matched group to avoid confounding. Associations were estimated using generalized estimating equations (GEE) with logit link, clustering by matched-set identifier, and stratified by infection trimester, reporting odds ratios (OR) and 95% confidence intervals (CI).
Results: A total of 4,275 pregnant women were enrolled in this study, including 855 in the exposed group and 3,420 in the unexposed group. In the full cohort, influenza-related hospitalization during pregnancy was significantly associated with increased risks of preterm birth (aOR = 1.94, 95% CI: 1.42-2.66), TLBW (aOR = 2.40, 95% CI: 1.08-5.37), LGA (aOR = 1.36, 95% CI: 1.13-1.65), high-risk infants (aOR = 1.96, 95% CI: 1.62-2.38), frail infants (aOR = 1.53, 95% CI: 1.32-1.77), and neonatal resuscitation (aOR = 1.23, 95% CI: 1.08-1.40). For the preterm birth analysis, 2,520 women (504 exposed and 2,016 unexposed) were included. For the term outcomes analysis, 3,975 women (795 exposed and 3,180 unexposed) were included. Influenza-related hospitalization during pregnancy was significantly associated with increased risks of preterm birth (aOR = 3.58, 95% CI: 2.56-5.26), TLBW (aOR = 2.58, 95% CI: 1.13-5.92), LGA (aOR = 1.39, 95% CI: 1.14-1.69), high‑risk infants (aOR = 1.60, 95% CI: 1.29-1.98), frail infants (aOR = 1.47, 95% CI: 1.26-1.71), and neonatal resuscitation (aOR = 1.21, 95% CI: 1.05-1.38). When stratified by trimesters, influenza hospitalization in the first trimester was significantly associated with higher risks of macrosomia (aOR = 3.16, 95% CI: 1.40-7.12) and high‑risk infants (aOR = 2.14, 95% CI: 1.11-4.15), whereas hospitalization in the third trimester was associated with elevated risks of TLBW (aOR = 2.61, 95% CI: 1.09-6.26), LGA (aOR = 1.41, 95% CI: 1.13-1.74), high‑risk infants (aOR = 1.59, 95% CI: 1.26-2.02), frail infants (aOR = 1.58, 95% CI: 1.33-1.87), and neonatal resuscitation (aOR = 1.33, 95% CI: 1.14-1.55).
Conclusion: Influenza-related hospitalization during pregnancy was associated with increased risks of adverse perinatal outcomes. However, this association may reflect the combined effects of influenza infection, illness severity, and hospitalization rather than influenza infection alone. Strengthening maternal influenza vaccination, timely antiviral treatment, and surveillance systems remains important to reduce severe influenza and its associated burden.
Keywords: Hospitalization; Influenza; Matched Cohort Study; Pregnancy Outcome; Pregnant Women.
. 2026 Nov 11:109228.
doi: 10.1016/j.ijid.2026.109228. Online ahead of print.
Maternal and Neonatal Outcomes Associated with Influenza-Related Hospitalization During Pregnancy: A Population-Based Matched Cohort Study in Suzhou, China, 2018-2024
Rui Wang 1 , Jinghui Sun 1 , Jianyang Wang 2 , Yuanyuan Zhang 1 , Cheng Liu 1 , Wanting Hong 3 , Ningning Du 4 , Shuai Shao 4 , Liling Chen 5
Affiliations Expand
- PMID: 43014658
- DOI: 10.1016/j.ijid.2026.109228
Abstract
Background: Physiological and immunological changes render pregnant women susceptible to influenza, leading to increased risks of severe illness and adverse pregnancy outcomes. These outcomes are major causes of perinatal mortality and morbidity, and fetal deaths (including miscarriage and stillbirth) pose a major public health challenge. However, population-based cohort studies on this topic, particularly from China, remain scarce. Therefore, clarifying the association between influenza infection and adverse pregnancy outcomes is critical for optimizing antenatal care and reducing maternal-neonatal risks.
Methods: We conducted a population-based matched cohort study among pregnant women in Suzhou, China, from October 2018 to September 2024, based on active surveillance of influenza-related acute respiratory or febrile illness (ARFI) hospitalizations. Exposed groups were RT-PCR-confirmed influenza infections among hospitalized ARFI pregnant women, excluding those with delivery outside Jiangsu Province, miscarriage or stillbirth in the current pregnancy, repeated ARFI-related hospitalizations during the same pregnancy, multiple gestations, or already postpartum at ARFI admission. Unexposed groups were selected from the same source population, matched 1:4 by age, last menstrual period, gravidity, and parity, excluding those with any ARFI hospitalization, delivery outside Jiangsu Province, miscarriage or stillbirth in the current pregnancy, or multiple gestation. For preterm birth analysis, we included only exposed women with gestational age 28-37 weeks and their matched controls. For term outcomes (macrosomia, term low birth weight (TLBW), small for gestational age (SGA), large for gestational age (LGA), high-risk infants, frail infants, 1-min Apgar < 7, and neonatal resuscitation), we excluded preterm births and their matched group to avoid confounding. Associations were estimated using generalized estimating equations (GEE) with logit link, clustering by matched-set identifier, and stratified by infection trimester, reporting odds ratios (OR) and 95% confidence intervals (CI).
Results: A total of 4,275 pregnant women were enrolled in this study, including 855 in the exposed group and 3,420 in the unexposed group. In the full cohort, influenza-related hospitalization during pregnancy was significantly associated with increased risks of preterm birth (aOR = 1.94, 95% CI: 1.42-2.66), TLBW (aOR = 2.40, 95% CI: 1.08-5.37), LGA (aOR = 1.36, 95% CI: 1.13-1.65), high-risk infants (aOR = 1.96, 95% CI: 1.62-2.38), frail infants (aOR = 1.53, 95% CI: 1.32-1.77), and neonatal resuscitation (aOR = 1.23, 95% CI: 1.08-1.40). For the preterm birth analysis, 2,520 women (504 exposed and 2,016 unexposed) were included. For the term outcomes analysis, 3,975 women (795 exposed and 3,180 unexposed) were included. Influenza-related hospitalization during pregnancy was significantly associated with increased risks of preterm birth (aOR = 3.58, 95% CI: 2.56-5.26), TLBW (aOR = 2.58, 95% CI: 1.13-5.92), LGA (aOR = 1.39, 95% CI: 1.14-1.69), high‑risk infants (aOR = 1.60, 95% CI: 1.29-1.98), frail infants (aOR = 1.47, 95% CI: 1.26-1.71), and neonatal resuscitation (aOR = 1.21, 95% CI: 1.05-1.38). When stratified by trimesters, influenza hospitalization in the first trimester was significantly associated with higher risks of macrosomia (aOR = 3.16, 95% CI: 1.40-7.12) and high‑risk infants (aOR = 2.14, 95% CI: 1.11-4.15), whereas hospitalization in the third trimester was associated with elevated risks of TLBW (aOR = 2.61, 95% CI: 1.09-6.26), LGA (aOR = 1.41, 95% CI: 1.13-1.74), high‑risk infants (aOR = 1.59, 95% CI: 1.26-2.02), frail infants (aOR = 1.58, 95% CI: 1.33-1.87), and neonatal resuscitation (aOR = 1.33, 95% CI: 1.14-1.55).
Conclusion: Influenza-related hospitalization during pregnancy was associated with increased risks of adverse perinatal outcomes. However, this association may reflect the combined effects of influenza infection, illness severity, and hospitalization rather than influenza infection alone. Strengthening maternal influenza vaccination, timely antiviral treatment, and surveillance systems remains important to reduce severe influenza and its associated burden.
Keywords: Hospitalization; Influenza; Matched Cohort Study; Pregnancy Outcome; Pregnant Women.