Description of fetal heart rate patterns at 20 to 24 weeks gestation

[摘要] ENGLISH ABSTRACT: Introduction - Accurate computerized analysis of the fetal heart rate (FHR) pattern has become more feasible and clinically relevant in recent years. Taking into account advances in neonatal care resulting in a declining lower limit for fetal viability as well as research into fetal effects of maternal high risk behaviour and escalating intra-uterine exposure to harmful toxins and drugs, fetal heart rate patterns need to be more accurately described in earlier gestations than what is currently available in literature. With advancing technology it is becoming possible to accurately record and interpret the FHR patterns from gestations as early as 20 weeks' gestation. By using the Monica AN24 transabdominal electrocardiographic fetal monitor and product specific software, we analysed early FHR patterns according to the Dawes-Redman criteria, as used in later gestations.Methods - The aim of our study was to describe patterns of FHR (short-term variability, basal heart rate, accelerations and decelerations) at 20-24 weeks' gestation. Physiological data were obtained from the routine second trimester fetal assessment by the Monica AN24 monitor as used in the Safe Passage Study. As of December 31, 2009, 411 participants completed their first fetal assessment and met our inclusion criteria. Because our aim was the description of patterns in pregnancies with a normal outcome, we excluded all adverse neonatal outcomes, preterm deliveries, babies with low birth weights as well as cases where delivery data were lost. After recordings of poor technical quality were also removed from our data pool, 281 recordings remained for analysis.Results - Distinct FHR patterns and quantifiable parameters of heart rate variability were consistently observed. In contrast to what has previously been published, accelerations of the FHR and reassuring baseline variation are present from as early as 20 weeks.Conclusion - Information from this study provides an important foundation for further studies of early FHR patterns and it will help us better assess the fetus at a crucial age for indicators of good outcome at early delivery.

[发布机构] Stellenbosch University