Study protocol for a randomized trial on timely delivery versus expectant management in late preterm small for gestational age pregnancies with an abnormal umbilicocerebral ratio (UCR): the DRIGITAT study.

BACKGROUND: The clinical inability to correctly identify late fetal growth restriction (FGR) within a group of fetuses who are identified as small for gestational age (SGA) is an everyday problem for all obstetrician-gynecologists. This leads to substantial overtreatment of healthy small fetuses but also inadequate detection of the growth-restricted fetuses that may benefit from timely delivery. Redistribution of the fetal circulation, signaled by an abnormal ratio of the Doppler velocity flow profiles of the umbilical artery and the middle cerebral artery, more specifically an increased umbilicocerebral ratio (UCR) (or its inverse: a decreased cerebroplacental ratio (CPR)), is an adaptation to chronic hypoxemia and nutritional scarcity with long-term consequences in survivors. The relevance of an abnormal UCR has been signaled extensively, and there is a general consensus that it is a signal of FGR, independent of size, with a strong association with poor outcomes. Yet, in the current literature, no comparisons of a monitoring-delivery strategy based on unfavorable UCR have been published. The objective of the Doppler Ratio In fetal Growth restriction Intervention Trial At (near) Term (DRIGITAT) is to evaluate if the timing of the delivery based on an abnormal UCR in late preterm fetuses identified as SGA improves neurodevelopmental outcomes at 2 years of age. METHODS: The DRIGITAT study is a national multicenter cohort study of women with singleton pregnancies between 32 and 37 weeks of gestation identified as SGA, with a nested randomized controlled trial (RCT) in case of an abnormal UCR (> 0.8). Recruiting centers are in The Netherlands. In the nested RCT, women are randomized to either immediate induction of labor or expectant management from 34 weeks in case of severely abnormal size (EFW or FAC < p3) and from 36 weeks in case of mildly abnormal size (EFW or FAC p3-p10). The primary outcome measure is the 7-point average difference in the composite cognitive score (CCS) and composite motor score (CMS) on the Bayley-3 at 2 years. Secondary outcome measures include a composite outcome of neonatal morbidity, perinatal mortality, mode of delivery, maternal quality of life, costs, and predictive value of serum biomarkers. Analyses will be by intention to treat. The required sample size is determined for the nested RCT as 185 patients. DISCUSSION: This study will provide insight into the diagnostic efficacy of UCR measurement in the evaluation of SGA fetuses in order to differentiate the healthy SGA fetus from the growth-restricted fetus and to determine if a fetus with abnormal UCR benefits from early delivery. TRIAL REGISTRATION: Healthcare Evaluation Netherlands NTR6663 . Registered on 14 August 2017.

On the relevance of microecosystems for risk assessment: some considerations for environmental toxicology.

Microecosystems (any multispecies system with at least two trophic levels and its abiotic surroundings, (partly) enclosed by artificial boundaries for the purpose of research) differ from natural ecosystems by reason of enclosure and scale. Their application to environmental toxicology has been of interest where fate and behavior of contaminants markedly modify the exposure of biota to them and hence the environmental hazard. Evaluation of literature data, both from a scientific and a regulatory point of view, indicates that a standardized microecosystem design is unlikely to contribute to environmental hazard rating if it were to replace currently used test schedules. On the other hand, microecosystems may be applied usefully for the evaluation of ambient environmental quality criteria, provided that the design is suitable for replicable long-term continuous exposure experiments. Also, they provide a possible means to appraise the validity of bench tests for the assessment of real-world hazards.