How do infectious diseases during pregnancy affect a child's health?

This month's guest expert is Dr Enny Paixao Cruz , an epidemiologist and Associate Professor at London School of Hygiene and Tropical Medicine, U. of London .

When I started my research career studying dengue in Brazil, I found that people who contracted the disease during pregnancy had a higher risk of adverse birth outcomes like stillbirth.

Then the 2015 Zika outbreak hit Brazil. We found that being infected with Zika during pregnancy also increased the risk of adverse birth outcomes such as microcephaly, where a baby’s head is smaller than expected.

So, I decided to keep researching the effect of infectious disease during pregnancy on a child’s health.

I'm now an Associate Professor at the London School of Hygiene & Tropical Medicine and working on a study funded by Wellcome’s Career Development Awards . We are researching whether contracting a range of infectious diseases during pregnancy could lead to some non-communicable conditions, like cancer, during childhood and adolescence .

While there are already some studies showing that this connection is plausible, they have a very small sample size. My study will investigate this connection on a much larger scale using the CIDACS Birth Cohort , which has data on millions of births in Brazil.

We’re linking large datasets

Brazil is a very large country, and we have large, high quality administrative datasets that are collected by the government. I’m working with a partner, CIDACS in Brazil, to link all this information together using a set of common variables.

So, we’ll use a cohort of live births from Brazil, and we’ll then link this to other data. For example, social and governmental information, and health data such as hospitalisation, mortality or having a specific infectious disease.

Using these datasets, we can study an individual’s exposure to infectious disease and then study the outcome in their children. Some of the outcomes we’re particularly interested in are childhood cancers like leukaemia and neuroblastoma, mental health conditions like schizophrenia, and also growth patterns like height and weight.

It’s going to be quite complex piecing it together but it’s very exciting that we have access to this data, and CIDACS has a lot of experience doing this.

We can tailor the recommendations to the outcomes

I'm not studying the effects of just one specific disease, I'm going to look at a range of infectious diseases.

For each of these diseases, if we find a link to developing a non-communicable chronic condition during childhood or adolescence, the recommendations for how to mitigate or avoid these outcomes will vary.

For example, we might find that a disease that’s preventable by vaccine causes a serious condition in later life. We can then share evidence that the vaccine is not only going to protect pregnant people from the infectious disease, but it will also protect their babies from developing a serious condition in later life.

Or we might find that being treated with antibiotics during pregnancy is a risk factor for babies developing obesity during childhood. So, we can then say that these babies are at risk of obesity and recommend early interventions to help prevent that.

Although our research uses data from one country, we are looking for biological links. That means our findings are likely to be true for anyone, anywhere.

We need more research that uses data outside high-income countries

As an epidemiologist, Wellcome’s Discovery Research Awards attracted me because it offers whatever you need to achieve your research goal. It’s quite flexible, offers training opportunities, supports you to reach people from different communities – and pushes you to aim high.

My study will run for eight years and that means I don’t have to rush to publish my work. I can wait to find the best evidence to answer my research questions. Our team will be based in London and Brazil and build research capacity on both sides.

When most people start to work with administrative data or routine data, they tend to think that it’s something you can only do in high-income settings. So, I think it’s huge that we are basing our study in a middle-income country, and we know that are data is good and can be trusted. It means that we can address problems that affect so many people around the world but are not important in high-income settings. For example, arboviruses like dengue and Zika that are not a threat for people that live here in London but are a huge problem for people living in South America and Southeast Asia.

Our study will show that good routine data is available outside of high-income settings – and that’s a great thing.

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