Understanding the placenta likely key to preventing stillbirth

The key to reducing the number of stillbirths is likely to be development of novel screening tests based on better understanding of normal and abnormal function of the placenta. This and other issues related to stillbirth are discussed in a Seminar in this week's edition of The Lancet.

Professor Gordon Smith, Department of Obstetrics and Gynaecology, Cambridge University, UK, and Dr Ruth Fretts, Harvard Medical School, Boston, MA, USA reviewed published literature from 1997 to present day to prepare the Seminar.

Stillbirth is a fetal death late in pregnancy. The most widely accepted definition is death of baby at or after 22 weeks or more of gestation, or of a baby weighing at least 500g. Stillbirth is the most common cause of death of a potentially viable baby. It affects one in 200 pregnancies, is around twice as common as death of a baby in the first four week of life, and 10 times more common than death from sudden infant death syndrome (SIDS). Further, while rates of SIDS have fallen dramatically over the last 10-20 years, rates of stillbirth have stayed constant or even slightly increased (England and Wales) in recent years.

The lack of improvement in stillbirth rates in recent years reflects the fact that the basic components of antenatal screening for the condition are largely unchanged over the last 40 years. The mainstay of screening in low risk women remains measurement of the height of the uterus with a tape measure.

Evaluation of more high tech methods, such as scanning all pregnant women in the last third of pregnancy, have consistently failed to show improved outcomes.

The authors discuss that more than 50% of stillbirths are likely to be related to abnormal function of the placenta. This can be due to separation of the placenta before birth; development of pre-eclampsia; or poor growth of the baby, due to failure of transport of oxygen and nutrients across the placenta. There is strong evidence that these events in late pregnancy may be related to abnormal development of the placenta in the first weeks following conception, even before a woman has attended for antenatal care.

They argue that improved understanding of the science behind placental function and dysfunction may allow development of novel screening tests. Such tests could be used to screen the apparently low risk population and identify those who are most likely to experience this devastating event.

Unfortunately, despite the fact that stillbirth is relatively common and that there has been so little progress in reducing the number of deaths, research in this area is not generally prioritised by funding bodies. Moreover, unlike cancer and heart disease, there is no stillbirth charity currently funding research. Addressing the lack of funding in these areas will be an essential first step to reducing the burden on this devastating and surprisingly common complication of pregnancy.

Professor Gordon Smith, Department of Obstetrics and Gynaecology, Cambridge University, UK T) +44 (0)1223 763888 / +44 (0) 7774 017656 E) gcss2@cam.ac.uk