Evidence of early first-trimester growth restriction in pregnancies that subsequently end in miscarriage F Mukri, a T Bourne, a,b,c C Bottomley, a,b C Schoeb, b E Kirk, a AT Papageorghiou a,b,d a Early Pregnancy, Gynaecological Ultrasound and MAS Unit, St George’s Hospital, London, UK b St George’s University of London, London, UK c Department of Obstetrics and Gynaecology, University Hospital Gasthuisberg, KU Leuven, Belgium d Fetal Medicine Unit, St George’s Hospital, London, UK Correspondence: Dr F Mukri, Early Pregnancy, Gynaecological Ultrasound and MAS Unit, St George’s Healthcare NHS Trust, Blackshaw Road, London SW17 0QT, UK. Email faizah_mukri@hotmail.com Accepted 27 May 2008. Objectives To examine whether viable early pregnancies that subsequently end in miscarriage exhibit evidence of first-trimester growth restriction. Design Prospective cohort study. Setting Early pregnancy unit (EPU) of a teaching hospital. Population Women attending EPU between 5 and 10 weeks of gestation. Methods Women with spontaneously conceived intrauterine, viable singleton pregnancies with certain last menstrual period and regular cycles were included. The deviation between the observed and expected crown–rump length (CRL) for gestation was calculated and expressed as a z score. Pregnancies were followed up until the 11–14 week scan, and the deviation between those that remained viable and miscarried subsequently was calculated. Main outcome measures Viability at 11–14 week scan. Results Over 6 months, 316 women met the inclusion criteria. Twenty-four (7.4%) women were excluded. Of the remaining 292, the pregnancy remained viable in 251 (86%) and 41 (14%) suffered a miscarriage. At the first transvaginal ultrasound, the z score of the mean measured CRL for pregnancies that remained viable was –0.82, SD 1.46, while in pregnancies that subsequently miscarried the z score was –2.42 and the CRL was significantly smaller, SD 1.31 (P < 0.0001). In the latter group, the initial CRL was below the expected mean for gestational age in all women, while in 61% (25/41), the CRL was at least 2 SDs below the expected mean. Conclusions CRL was significantly smaller in pregnancies that subsequently ended in miscarriage. This suggests that early first- trimester growth restriction is associated with subsequent intrauterine death. Keywords Early pregnancy, growth restriction, miscarriage, ultrasound. Please cite this paper as: Mukri F, Bourne T, Bottomley C, Schoebb C, Kirk E, Papageorghiou A. Evidence of early first-trimester growth restriction in pregnancies that subsequently end in miscarriage. BJOG 2008;115:1273–1278. Introduction Transvaginal ultrasound (TVS) is a commonly performed investigation during early pregnancy and is used to confirm the pregnancy location, viability and gestation. Measurement of embryonic crown–rump length (CRL) is conventionally performed to confirm the gestational age of the pregnancy. The diagnosis of miscarriage is made in at least 10–20% of pregnancies in the first trimester. 1 However, in pregnancies where fetal viability is demonstrated, the rate of subsequent miscarriage is lower (2–16%) but depends on the population studied, the indication for the scan and gestational age. 2–4 Previous studies have evaluated various factors in the predic- tion of pregnancy outcome. Ultrasound findings that have been associated with subsequent miscarriage include a slow embryonic heart rate, a small gestational sac diameter and a larger-than-expected yolk sac diameter. 5,6 Smaller-than- expected CRL has also been associated with subsequent pregnancy loss in studies involving women with threatened miscarriage and in women who have undergone assisted con- ception techniques. 7–9 One possible link between a small CRL and subsequent miscarriage is that chromosomal defects not only have a high intrauterine lethality rate 10 but can also be associated with fetal growth restriction in the first trimester of ª 2008 The Authors Journal compilation ª RCOG 2008 BJOG An International Journal of Obstetrics and Gynaecology 1273 DOI: 10.1111/j.1471-0528.2008.01833.x www.blackwellpublishing.com/bjog General obstetrics