Jane McCredie: Genetic scapegoats

“LOOK at beautiful pictures, study perfect pieces of statuary, forbid as far as possible the contemplation of unsightly and imperfect models”, was the advice Mrs Emma Drake MD gave to pregnant women in her 1908 instructional manual, What a Young Wife Ought to Know.

Medical experts of the time believed the sights and experiences a woman was exposed to during pregnancy would help determine the health, even the physical appearance, of her unborn child.

Nineteenth-century Parisian surgeon Jean Samuel Pozzi, for example, declared “the influence of strong emotions [during pregnancy] on the production of monstrosities seems established by very strong proofs”, while Mrs Drake noted the striking resemblance of Italian infants to baby Jesus, apparently a result of the hours their mothers had spent contemplating images of the Madonna.

Such ideas might seem laughable to us now, but the burgeoning science of epigenetics is making us look again at how a woman’s experiences before and during pregnancy might affect fetal development and the future health of her baby.

Epigenetic changes, which may be triggered by environmental factors such as chemical exposure or diet, don’t alter our overall genetic make-up but they can lead to particular genes being switched on or off (or being up- or down-regulated).

That, in turn, may affect health outcomes, making us more susceptible to particular diseases, for example.

Our growing understanding of these potentially modifiable epigenetic effects could open up new pathways for prevention, but does it also raise a renewed risk of stigmatising women whose children experience health problems, in the same way their 19th century forebears were held responsible for the birth of a child with disabilities?

A group of US researchers — including scholars in public health, history of science, anthropology and philosophy — is arguing we need to ensure the potential health benefits of epigenetic research do not come at the cost of constraining women’s freedom.

“There is a long history of society blaming mothers for the ill health of their children”, the group writes in Nature, warning that “exaggerations and over-simplifications [of epigenetic research] are making scapegoats of mothers, and could even increase surveillance and regulation of pregnant women”.

They believe there’s a precedent. Punitive measures, even criminal sanctions, have been imposed in recent decades on women consuming alcohol or illegal drugs during pregnancy, in some cases on the basis of pretty sketchy evidence.

So what are we to make of epigenetic studies suggesting a link between poor maternal diet, say, and a child’s future risk of obesity, diabetes and other adverse health outcomes?

These authors argue the discussion often focuses too narrowly on the behaviour of the pregnant woman, ignoring other potential factors such as socioeconomic status or the health behaviours of the father (a child’s health may also be affected by epigenetic changes in sperm, triggered by smoking and other factors).

When a 2012 study found an increased mammary cancer risk in daughters and granddaughters of pregnant rats fed a high-fat diet, it prompted media headlines such as “Why you should worry about grandma’s eating habits” and “Think twice about that bag of potato chips because you are eating for more than two”.

As the group of researchers point out in their Nature article, the reports did not acknowledge the rats had been specially bred for high cancer rates and glossed over inconsistent results (the third generation offspring of those on the high-fat diet actually had lower cancer rates than controls, for example).

Media reports of such studies also often fail to acknowledge that findings in animals will not necessarily translate into humans.

Epigenetic research is offering extraordinary insights into the origins of disease, but it’s never going to hold all the answers. In fact, if it leads to an over-simplified focus on blaming mothers, it could even become part of the problem.

When the aim is improved child health, the chemical markers placed on our genes are part of the picture, but they need to be seen in the context of the myriad social factors affecting the health and functioning of children and their parents, mothers and fathers.
 

Jane McCredie is a Sydney-based science and medicine writer.