BJOG Release: Doctors Find Fetal Growth Factors Associated With Early Miscarriage

Main Category: Pregnancy / Obstetrics
Article Date: 04 Sep 2008 - 1:00 PDT

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A new study published in BJOG examines the reasons why some women have miscarriages during the first months of pregnancy.

There is a one in five risk of an early miscarriage in the first three months of pregnancy. Previous research has shown factors which increase the chance of a spontaneous miscarriage include high levels of alcohol intake and smoking during pregnancy, as well as the consumption of certain foods such as blue-veined cheeses.

Specialists in early pregnancy ultrasound at the Early Pregnancy Unit, St George's Hospital, University of London; studied 292 women with certain menstrual histories expecting singleton pregnancies. Detailed obstetric and menstrual histories were recorded to assess the gestation of pregnancy.

Transvaginal ultrasound (TVS) was used to confirm the pregnancy location and viability and to measure the size of the fetus, known as its 'crown rump length' (CRL). The size of the fetus was compared to standard growth measurements based on gestational age.

Researchers found that 100% of the pregnancies that miscarried registered lower than expected CRL readings for their gestational age and in 61% of the women who miscarried, the fetus was very significantly smaller than expected for the gestational age. The fetuses which miscarried were also shown to be significantly smaller than those that did not miscarry. They conclude that this indicates that the fetuses that miscarried were showing delayed growth which could be detected by ultrasound scan prior to the miscarriage.

Researchers speculate that these findings point to the possibility of chromosomal abnormality in the fetus or placental dysfunction, either of which may restrict the normal growth of the fetus, thereby leading to the miscarriage.

Researchers suggest that a smaller than expected CRL is a possible marker of early pregnancy failure and that women identified as having such a condition should receive counselling and be offered a further ultrasound scan in two weeks to check whether the pregnancy is ongoing.

Dr Faizah Mukri, who co-authored the paper, said "We found that the length of the embryo, measured as crown-rump length (CRL), was significantly smaller in pregnancies that subsequently ended in miscarriage. The greater the difference between the observed and expected CRL at the time of the scan, the greater was the risk of subsequent pregnancy failure before 12 weeks.

"It may be reasonable to offer these women a further ultrasound before their 'routine' 12 week scan to confirm that the pregnancy has not failed. Although performing such a repeat examination is unlikely to affect the ultimate outcome of the pregnancy, recognition that a smaller than expected CRL is a marker of possible impending miscarriage may help in counselling and reduce the number of women who are found to have unrecognised failed pregnancies at the time of the 12 week scan, with its associated psychological impact."

Professor Philip Steer, BJOG editor-in-chief, said "Miscarriage is heart-aching for many women, especially first-time mothers. However, it is more common than most people think and it is the body's natural way to reject a fetus that is not growing normally. This research has shown that a small CRL can indicate that a miscarriage is more likely to occur in future, and more of this kind of research should be undertaken to test the validity of the hypothesis. If the findings of this study are confirmed, healthcare professionals will be in a better position to prepare the mother for the worst and to support her during this difficult time."

BJOG: An International Journal of Obstetrics and Gynaecology is owned by the Royal College of Obstetricians and Gynaecologists (RCOG) but is editorially independent and published monthly by Wiley-Blackwell. The journal features original, peer-reviewed, high-quality medical research in all areas of obstetrics and gynaecology worldwide. Please quote 'BJOG' or 'BJOG: An International Journal of Obstetrics and Gynaecology' when referring to the journal.

Reference

Evidence of early first-trimester growth restriction in pregnancies that subsequently end in miscarriage. Mukri F, Bourne T, Bottomley C, Schoebb C, Kirk E, Papageorghiou A
BJOG 2008;115:1273-1278.

Royal College of Obstetricians and Gynaecologists