OBJECTIVES: Of 780 000 births annually in the UK, around 3300 are stillborn, a rate of approximately 4 per 1000 births. Traditional epidemiological associations are based on historic data. The aim of this study was to document contemporary demographic findings in a large series of > 1000 deaths in utero in London and compare these with national datasets.
METHODS: From a dedicated database, including > 400 data fields per case, of fetal, infant and pediatric autopsies performed at Great Ormond Street Hospital and St George's Hospital, London, we extracted information on all intrauterine deaths, excluding terminations of pregnancy, from 2005 to 2013, inclusive. Demographic data were analyzed according to the gestational age at which fetal death occurred (second-trimester intrauterine fetal death (IUFD), subdivided into early (< 20 weeks) and late (20-23 weeks) IUFD, and third-trimester stillbirth (≥ 24 weeks)) and compared with national datasets when available, using Mann-Whitney U-test and comparison of proportions testing as appropriate.
RESULTS: Data were available from 1064 individual postmortem reports examining intrauterine deaths delivered between 12 and 43 weeks' gestation, including 425 IUFDs (246 early and 179 late) and 639 stillbirths. Compared with the overall UK pregnant population, women in whom an intrauterine death occurred were significantly older and more obese. White mothers had a higher proportion of stillbirths (as opposed to IUFDs) than did non-white mothers, whereas black mothers had a higher proportion of IUFDs relative to stillbirths. Increased body mass index was associated with increased risk across all groups. Women who had uterine fibroids, those who had a history of vaginal bleeding in early pregnancy and those who had undergone assisted conception had a relatively higher proportion of IUFDs than stillbirths.
CONCLUSIONS: Based on a large series of >1000 autopsies in cases of intrauterine death, these data highlight the increased risk for fetal loss associated with maternal demographic factors in contemporary clinical practice, particularly associations with increased maternal age and body mass index. Among women in whom an intrauterine death occurs, maternal ethnicity, mode of conception and gynecological history are associated with differing timing of fetal loss. Further research is required to understand the mechanisms involved in such maternal factors in order to develop preventative strategies. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.