Photo Credit – CDC
#17,155
We've long known that influenza and pregnancy are a bad combination - one that can endanger both the mother and unborn child’s life – and that women are more susceptible to influenza while (and just after) they are pregnant (see Study: Outcomes Of Infants Born To Women With Influenza A(H1N1)pdm09).
It is for this reason that the CDC encourages all pregnant women to get the flu shot (see Pregnant Women & Influenza (Flu)), but uptake is far from optimal.
Some of this reluctance is due to the persistent anti-vaccine rhetoric on the internet and in the media - including unfounded claims that the 2009 H1N1 vaccine was responsible for `thousands’ of miscarriages.
At the same time we've seen numerous studies suggesting that the offspring whose mothers were infected - with influenza, or other viral illnesses - during their pregnancy may be at higher risk of a wide spectrum of psychological, developmental, or physical problems later in life.
A few examples include:
JAMA Psych: Long-term Risk of Neuropsychiatric Disease After Exposure to Infection In Utero
Pregnancy, Influenza & Elevated Psychosis Risks In Adult Offspring
JAMA Psych: Long-term Risk of Neuropsychiatric Disease After Exposure to Infection In Utero
Molecular Psy.: Increased Autism Risk Linked To Prenatal Fever
With influenza currently raging across the nation (see CDC FluView Week 47: Most of The Nation at High or Very High Levels Of ILI), we've a timely Systematic Review and Meta-Analysis published last week in the Journal Viruses on the increased risk of congenital abnormalities (CAs) in the offspring of women who were infected with influenza during their first trimester.
First-Trimester Influenza Infection Increases the Odds of Non-Chromosomal Birth Defects: A Systematic Review and Meta-Analysis
Ákos Mátrai 1,2,3,Brigitta Teutsch 2,4,Alex Váradi 4, Péter Hegyi 2,4,5, Boglárka Pethő 1,2, Akari Fujisawa 2,6, Szilárd Váncsa 2,4,5, Balázs Lintner 1,2, Zsolt Melczer 1,2 andNándor Ács 1,2,*
Viruses 2022, 14(12), 2708; https://doi.org/10.3390/v14122708
ABSTRACT
Viral infections during pregnancy raise several clinical challenges, including birth defects in the offspring. Thus, this systematic review and meta-analysis aims to prove and highlight the risk of birth defects after first-trimester maternal influenza infection. Our systematic search was performed on 21 November 2022. Studies that reported maternal influenza infection in the first trimester and non-chromosomal congenital abnormalities were considered eligible.
We used odds ratios (OR) with 95% confidence intervals (CIs) to measure the effect size. Pooled ORs were calculated with a random effects model. Heterogeneity was measured with I² and Cochran’s Q tests.
We found that first-trimester maternal influenza was associated with increased odds of developing any type of birth defects (OR: 1.5, CI: 1.30–1.70). Moreover, newborns were more than twice as likely to be diagnosed with neural tube defects (OR: 2.48, CI: 1.95–3.14) or cleft lip and palate (OR: 2.48, CI: 1.87–3.28). We also found increased odds of developing congenital heart defects (OR: 1.63, CI: 1.27–2.09).
In conclusion, influenza increases the odds of non-chromosomal birth defects in the first trimester. The aim of the present study was to estimate the risk of CAs in the offspring of mothers affected by first-trimester influenza infection.
(SNIP)
4. Discussion
The importance of viral infections will increase as we face growing risks of pandemics, which may affect the pregnant mother and the fetus [42]. Viral infections during pregnancy raise several clinical challenges, including adverse pregnancy outcomes and birth defects in the offspring [3]. During embryogenesis, the development of different organs and organ systems occurs one after the other and parallel to others. Almost every organ system develops in the first 12 weeks of pregnancy, so any effect on the embryo during this period may significantly influence the development of birth defects.
This systematic review and meta-analysis evaluated the effects of influenza infection in the first trimester of pregnancy on the development of non-chromosomal birth defects.
(SNIP)
5. Conclusions
In conclusion, our systematic review found that influenza in the first trimester is associated with non-chromosomal birth defects, primarily congenital heart defects, neural tube defects and oral clefts. Therefore, influenza prevention by vaccination before or during pregnancy is highly recommended. Moreover, if influenza has already manifested itself, proper antipyretic treatment should be started.
Although this review and meta-analysis was restricted to women who had lab-confirmed influenza during their first trimester, we've seen other studies - involving influenza and other viral infections (including COVID) - which have produced similar findings.
While the exact mechanism behind these birth defects hasn't been identified, prolonged maternal fever has often been cited as a likely factor (see Molecular Psy.: Increased Autism Risk Linked To Prenatal Fever).
The authors cite the importance of limiting fever in today's report, writing:
Further studies have shown that if fever during an influenza infection was relieved effectively with antipyretic drugs, malformations are less likely to develop [30]. Several studies have also shown that taking folic acid and maternal vitamins during the first trimester of pregnancy can reduce the odds of developing birth defects [30,56].
The authors further state:
Translating scientific results into everyday practice has crucial importance [56]; therefore, we should make efforts to prevent influenza during pregnancy and highlight the importance of vaccination against flu and antipyretic therapy.
Whether it is influenza, COVID, or any other viral illness, the benefits of avoiding infection - particularly during a woman's first trimester - are becoming increasingly obvious.
