When an embryo is growing slowly during the first trimester it may portend an increased risk for miscarriage according to an English study to be presented at the 2012 British Fertility Society meeting. Armed with this valuable information women may be able to gain access to treatments that may reduce the risk of a miscarriage happening.
The study(1) - from the University of Nottingham - studied over 500 single and twin pregnancies and found that 78% of embryos from single-baby pregnancies which resulted in miscarriage were found to have slow growth. These embryos that miscarried were within the smallest 5% category of embryos during the first trimester.
By comparison, embryo growth restriction was rare in single pregnancies that did not miscarry: 98.1% of these babies grew normally. In twin pregnancies growth restriction was less predictive occurring in only 28.6% of twin pregnancies that miscarried.
A number of factors can contribute to poor embryonic growth which if identified and treated in a timely fashion maybe correctable. Diagnosis may lead to protective treatments being used in early pregnancy to promote healthier embryo growth and reduce loss, one of those key factors is uterine blood flow; consultant gynecologist, Dr Raj Mathur who was involved in the study highlighted this possibility stating that:
"...We also need to look at blood supply to the embryo..."
The research was led by Dr Shyamaly Sur, who also echoed concern about restricted blood flow stating that:
"More research is now needed to investigate the relationship between growth and the underlying causes of miscarriage in more detail."
"We are focusing on how blood flow to the womb lining and embryo quality influence conception rates and subsequent miscarriage."
"Our study also provides the clearest evidence yet that restricted growth in single embryos during the early stages of pregnancy is related to subsequent miscarriage in that pregnancy."
"We hope that this work will go towards developing a new system to identify pregnancies at risk of miscarriage by using evidence of early growth restriction as a factor."
The study concludes: "growth restriction is a good predictor of miscarriage."
Blood flow dynamics to the uterus can be measured prior to pregnancy with doppler ultrasound which can pick up restricted blood flow patterns at implantation sites before conception occurs. For women who have had a prior miscarriage uterine blood flow studies can provide invaluable information and allow for compassionate early intervention. This is the kind of work that a reproductive immunologist does.
Certain blood tests can also identify women at risk of developing poor uterine blood flow; a standard miscarriage panel includes tests for clotting factors and genetic blips like MTHFR which can lead to an increased tendency for blood clotting.
Another factor which can be involved in poor embryonic growth is a lack of thyroid hormone, specifically free T4 which the baby needs to be able produce it's own thyroid hormones that support growth. If you have had a miscarriage or have a slow growing embryo insist on having your free T4 tested - not just TSH - to check that you have adequate levels of thyroid hormones. A TSH test alone is not sufficient to assess thyroid well-being in pregnancy and should always be accompanied by a free T4 test if miscarriage risks are suspected. Ideally the TSH should be well below 2.5 mIU/ml and the free T4 in the top half or third of the reference range.
One other not to be neglected factor is the risk of celiac disease. Increasingly celiac disease is being identified in women with infertility and is known to cause poor embryonic growth. If you have had a miscarriage or have slow embryonic growth make sure that you do not have celiac disease which can be checked with a simple blood test. You need to be eating gluten regularly for this test to be accurate.
If uterine blood flow is restricted anticoagulant medications can restore good flow and ensure that the baby is able to grow at an optimal rate. Reproductive immunologists typically offer this kind of preventative care - and treatment - to women who have had a miscarriage or failed IVF. Suppositories of Silenafil are proven to improve blood flow and reduce miscarriage risks too. Both require a prescription.
If your embryo is slow-growing, don't wait for a miscarriage to happen, ask about treatments to maximize uterine blood flow and optimize thyroid hormones if they are low to give your baby the environment it needs to support healthy growth and a full-term pregnancy.
Press release from the British Fertility Society January 7 2012
BBC News Health. 6 January 2012 Last updated at 19:55 ET