Scientists identify cause of life threatening pregnancy complication

New work shows how the developing placenta may cause the potentially fatal condition pre-eclampsia to develop through attempts to take over the mother’s metabolism for the survival of the foetus.

Pre-eclampsia can strike up to 10% (around 75,000) of pregnancies each year. This condition strikes in the second half of pregnancy, developing rapidly to give high maternal blood pressure and protein in the urine. It can lead to fits, and even the death of mother and baby. At present, the only ‘cure’ is giving birth to the baby. Until now there has been no evidence of what might cause pre-eclampsia to develop.

In most pregnancies development of the blood supply to the placenta (vascularisation) is completed at around 20 weeks into the pregnancy. However if this fails to develop normally, the growing placenta starts to pump out a hormone called neurokinin B. This hormone seems to be inactive in the foetus, but a team led by Professor Phil Lowry (University of Reading) has recently deduced that once it crosses the placenta into the mother it is processed differently; neurokinin B causes the mother’s blood pressure to rise, which means that more nutrients are able to reach the foetus. This rise in blood pressure leads directly to the condition called pre-eclampsia.

Professor Lowry says ‘We now believe this condition arises because the placenta tries to compensate for the poor vascularisation. By pumping out this hormone it takes control of the mother’s body in an attempt to force it to divert resources to the uterus and thus the placenta. In its attempt to correct the situation, the placenta threatens the survival of both mother and baby’.

He continued ‘We hope that this understanding of this condition will allow us to develop methods for early diagnosis and be able to treat pre-eclampsia before it threatens the wellbeing or survival of mother and baby. From a scientific perspective, it’s interesting that a hormone can be processed differently in the placenta and the mother. This new concept has broader implications for many other hormones that the placenta secretes to control the mother’s metabolism and could hail the dawning of a new understanding of how the placenta works. There is a lot of work ahead’.