“Don’t drink, avoid sugary snacks and, of course, don’t forget to take your folic acid.” If only it were that simple.
The popular narrative tells us that pregnancy is a magical phase in a person’s life, but it is not all roses and unicorns. Pregnancy can undoubtedly be one of the most physically and emotionally challenging experiences. It has long been accepted that a mother’s health status directly impacts the foetus, however, now researchers from St John’s College, Cambridge University have shown that even if the mother is experiencing poor health, for example, due to malnutrition, the placenta can adapt to increase the amount of oxygen and nutrients it transports to the foetus during pregnancy.
The placenta is a temporary organ meaning it’s only present and attached to the lining of the womb during pregnancy. It functions to separate mother and foetus blood supplies whilst providing a critical link between the two. By producing hormones to promote foetal development, the placenta also protects the foetus against bacterial infection whilst supplying oxygen and nutrients from the mothers’ blood supply. Aside from this, the placenta is largely a mystery to scientists and medical professionals. Not least since it is notoriously difficult to study pregnant women, but also because the placenta is a temporary organ that is only present during pregnancy.
The demands of a growing foetus are high and can worsen existing micronutrient deficiencies or even cause them. The World Health Organisation (WHO) estimates that more than 2 billion people globally consume a nutritionally deficient diet, which has the potential to cause pregnancy complications. Similarly, around 140 million people live at high altitudes, above 2500 metres, with reduced oxygen levels. Restricted oxygen levels during pregnancy have previously been associated with miscarriage and foetal growth restriction.
So how exactly can healthy babies be born in these extreme conditions?
The study, published in Proceedings of the National Academy of Sciences (PNAS), aimed to determine what is needed for a healthy placenta to complete its crucial functions during pregnancy. Inducing reduced oxygen levels, known as hypoxia, in pregnant mice, researchers investigated the effects these conditions had on the overall placental function as well as specifically examining the organs’ mitochondria in the distinct transport and endocrine zones of the placenta. The researchers revealed that the placental mitochondria adapt in hypoxic environments to ensure there is still sufficient oxygen levels reaching the foetus. They showed that the mitochondria modulate their respiration, substrate use and density to best support the energy demands of the foetal tissues under hypoxic conditions.
As explained by lead scientist Dr Amanda N Sferruzzi-Perri, “Mitochondria in the placenta work out how to use oxygen and nutrients in the most efficient way so it is still sufficient for transfer to the fetus even in challenging pregnancies. When the placenta cannot compensate for the challenges, then this can lead to complications such as fetal growth restriction.”
Foetal growth restriction affects around ten per cent of all births and strongly correlates with poorer health outcome of the baby. By understanding the mechanisms that fail and lead to these circumstances, the scientists suggest they may be able to optimise placental function in challenging pregnancies, with the hope of minimising or preventing foetal growth restriction altogether.
Dr Sferruzzi-Perri is already planning upcoming research to further understand this compensatory mechanism, stating that “the next step would be to target mitochondria in the placenta to alter their function and improve pregnancy success in women where we know the outcome might be poor.”
This post was written by Ella Mercer (She/her) and edited by Karolina Zieba (She/her).