Predicting the outcome of pregnancies that threaten to miscarry has always been a difficult task for healthcare providers. Scientists in the UK who have been researching fertility have stated that the outcome of such pregnancies can now be predicted accurately.
About 20% of all pregnancies get complicated by a threatened miscarriage. Of these, up to 20% would miscarry*. This was stated by Dr Kaltum Adam, an honorary clinical research fellow at St Mary’s Hospital in Manchester (UK), while presenting at the annual meeting of the European Society for Human Reproduction and Embryology.
She further stated,
“However, at present we have no way of predicting which threatened miscarriages will result in the end of the pregnancy and so we are unable to target attempts to rescue the pregnancy at the right women or to offer them counselling.” “This has led to wasteful and potentially harmful interventions, including unnecessary blood tests, ultrasound scans, hospital admissions for bed rest, sexual abstinence, low dose aspirin and progesterone supplementation.”
A total of 112 women with threatened miscarriages were followed by Dr. Adam and her colleagues between 2009 and 2010. All women were 6-10 weeks pregnant and remained in the study for duration of 5 weeks. During the study all women had ultrasound scans and weekly charting of pain and bleeding. They also underwent weekly blood tests to check the levels of progesterone and the human chorionic gonadotrophin (hCG), commonly known as the pregnancy hormone.
Dr. Adam, after analysing the data on the outcomes of these pregnancies was clearly able to identify six factors that had the most impact on the risk of miscarriage. These were: a history of subfertility, levels of progesterone, levels of hCG, the length of the foetus, how much bleeding had occurred, and the gestational age of the baby.
When none of these six factors were on their own able to predict accurately the risk of miscarriage, the researchers created a “Pregnancy Viability Index” (PVI). PVI was a combination of two of factors, the amount of bleeding that had occurred and the levels of hCG. It was found to be a consistently reliable method to predict which pregnancies threatened by miscarriage would actually miscarry.
Dr. Adam** stated,
“By the end of the study period, the PVI was able to accurately predict the pregnancy outcome in 94% of women who had ongoing pregnancies (its positive predictive value), and also predicted the outcome in 77% of women whose pregnancy ended in miscarriage (its negative predictive value).” “This research has, for the first time, offered us a robust tool to begin to attempt to rescue pregnancies threatening to miscarry, when, currently, all we can do is fold our hands and hope for the best.”
PVI will also help physicians to stay away from interventions that are not needed. She further states,
“Every woman attending a unit with a threatened miscarriage has initial blood tests and a scan as part of her care. Additionally, some women are subjected to repeated blood tests and ultrasound scans to monitor the pregnancy. The use of the PVI will negate these in the vast majority (80%) of these women, as we will be able to reassure them of a high likelihood of pregnancy continuation and that there is little additional value in doing further testing. Furthermore, psychological counselling and support could be targeted at the women most likely to miscarry, in order to reduce anxiety levels and improve their overall experience.”
“The PVI will facilitate further investigations of the remaining 20% of these pregnancies that do go on to miscarry, and we are hopeful that by identifying factors that impact significantly on pregnancy outcome we will be able to gain a better understanding of the process of threatened miscarriage. This, in turn, may enable us to design more effective interventions to rescue these pregnancies.”
“We were limited by the size of our study and feel that further enhancements can be made to the PVI in a larger definitive study in which we could include more of the six factors that we have found to be important in miscarriage.”
Dr Adam and her team are seeking funding in order to conduct a larger study. This would enable them to validate the PVI model with a sample size of at least 1000 women.
No additional equipment is required in the clinic in order to use the PVI. Dr Adam concludes:
“This is the huge attraction of the PVI. It lends itself to widespread adoption because it is simple, inexpensive and reproducible, without the need for sophisticated equipment or gadgets,”
* In the UK approximately 250,000 miscarriages occur every year, causing significant psychological distress to affected women and their families.
** The PVI figures in the original abstract have changed following further analysis and so should not be used. The updated PVI is the one used in this press release to give the positive and negative predictive values.
The study was funded by a Biomedical Research Grant from Central Manchester University Hospitals (Manchester, UK).
Source: European Society for Human Reproduction and Embryology
Written by Barry Windsor