Photo Credit – CDC
It’s been well documented 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. It is for this reason that the CDC encourages all pregnant women to get the flu shot (see Pregnant Women & Influenza (Flu)).
These risks were well illustrated in an open access research article in the BMJ in 2011 (Perinatal outcomes after maternal 2009/H1N1 infection: national cohort study) that found that pregnant women who were admitted to the hospital with an H1N1 infection experienced a 3 to 4 times higher rate of preterm birth, 4 to 5 times greater risk of stillbirth, and a 4 to 6 times higher rate of neonatal death.
But over the past decade we’ve also seen evidence of a less obvious, and long-delayed, impact of these type of infections. Namely, an increase in a variety of child, adolescent, and adult development disorders experienced by offspring who were exposed to the flu (or the mother’s immune response) while in the womb.
A few examples include:
- In a 2004 study (Serologic evidence of prenatal influenza in the etiology of schizophrenia Brown et al.) found a 7-fold increase in the risk of developing schizophrenia when exposed to influenza during the first trimester. No increased risk was found for exposure during the second and third trimester.
- Another study from 2008 (Structural brain alterations in schizophrenia following fetal exposure to the inflammatory cytokine interleukin-8 Ellman et al.) suggested that it was prenatal exposure to a type of protein - (proinflammatory cytokines, specifically interleukin-8) – produced by the body during viral infections, that can lead (in rare cases) to brain abnormalities.
- In 2012 research by a team at UC Davis found that fever (from any cause) during pregnancy more than doubled the odds of having a child with autism or developmental delays (see Is Maternal Influenza or Fever During Pregnancy Associated with Autism or Developmental Delays? Results from the CHARGE (CHildhood Autism Risks from Genetics and Environment) Study Zerbo et al.)
- In November of 2012, in Of Pregnancy, Flu & Autism, we saw a study that found a twofold increase in autism among children with prenatal influenza exposure, and a threefold increase in autism among children with prolonged prenatal fever exposure
- And just last year (May, 2013) we looked at a JAMA Psychiatry report that linked bipolar disorder (BD) to influenza exposure while still in the womb (see Pregnancy, Influenza, & Bipolar Disorder In Offspring).
These studies are admittedly small and less than conclusive, and while they suggest an increase in relative risk over pregnancies without fever or viral infection – in terms of absolute risk – the odds that a mother’s fever or viral infection during pregnancy would result in a developmentally challenged child remains low.
We’ve a new study, this time appearing in the American Journal of Psychiatry that adds to, and reinforces some of these earlier studies. While not finding a statistically significant link between maternal pregnancy and bipolarity in offspring (odds ratio of 1.26), when they refined it to bipolar disorder with psychosis, they determined a nearly fivefold increased risk.
The authors explain:
“Since prenatal influenza has been previously associated with schizophrenia, a disorder characterized in large part by psychotic episodes such as hallucinations and delusions, our results support the hypothesis that maternal influenza exposure may preferentially increase the risk for psychosis apart from traditional diagnostic categories.”
Although more research is needed to validate these findings, the authors suggest that prevention of maternal influenza infection may decrease the incidence of bipolar disorder with psychotic features in the population.
Sarah E. Canetta, Ph.D.; Yuanyuan Bao, M.S.; Mary Dawn T. Co, M.D.; Francis A. Ennis, M.D.; John Cruz, B.S.; Masanori Terajima, M.D., Ph.D.; Ling Shen, Ph.D.; Christoph Kellendonk, Ph.D.; Catherine A. Schaefer, Ph.D.; Alan S. Brown, M.D., M.P.H.
Objective The authors examined whether serologically confirmed maternal exposure to influenza was associated with an increased risk of bipolar disorder in the offspring and with subtypes of bipolar disorder, with and without psychotic features.
Method The study used a nested case-control design in the Child Health and Development Study birth cohort. In all, 85 individuals with bipolar disorder were identified following extensive ascertainment and diagnostic assessment and matched to 170 comparison subjects in the analysis. Serological documentation of maternal exposure to influenza was determined using the hemagglutination inhibition assay.
Results No association was observed between serologically documented maternal exposure to influenza and bipolar disorder in offspring. However, maternal serological influenza exposure was related to a significant fivefold greater risk of bipolar disorder with psychotic features.
Conclusions The results suggest that maternal influenza exposure may increase the risk for offspring to develop bipolar disorder with psychotic features. Taken together with earlier associations between prenatal influenza exposure and schizophrenia, these results may suggest that prenatal influenza is a risk factor for psychosis rather than for a specific psychotic disorder diagnosis.
Obviously this is a major concern for expectant mothers, but we’ve also seen evidence that the influenza virus can be neurotropic - capable of infecting and damaging brain cells – in people of any age, not just those in the womb.
- see Revisiting The Influenza-Parkinson’s Link
- see Lancet: The Influenza - Guillain Barré Syndrome Connection
- see Stanford Study Finds Influenza – Narcolepsy Connection
When you consider the potential long-term health effects of influenza infection – rare or not – it makes sense to do whatever one can reasonably do to avoid infection.
And that means getting the flu shot every year, avoiding people when they are obviously sick, and practicing good flu hygiene (covering coughs, washing hands, avoid touching face) year round.