Optimising nearest neighbour information—a simple,efficient sampling strategy for forestry plot imputation using remotely sensed data

The rapid adoption of LiDAR-assisted forest inventory, together with nearest neighbour imputation, has created new challenges for those involved in sample selection. It is not obvious a priori what type of sample will be the most efficient when used with imputation. In this paper we explore a number of sampling approaches, including conventional methods such as stratification, spatial methods based on tessellations, and balanced sampling. We introduce a new approach called nearest centroid (NC) that optimises the survey design by using the distance properties of the sample in the space defined by the auxiliary variables, and examine this and other methods across a range of survey situations and objectives. The NC method is shown to be highly efficient when compared with other methods and is very flexible in the way it can be implemented.     

Resultados perinatales tras prueba diagnóstica invasiva en el embarazo

IntroductionInvasive prenatal diagnostic techniques allow us to conduct genetic tests. The development of non-invasive techniques has reduced their use. The foetal loss rate following an invasive procedure is considered to be around 1%. The published data is heterogeneous however, although everything indicates that the risk has been overestimated, we need to conduct further studies.Material and methodsIn our single-centre retrospective study we analysed the procedures carried out using invasive prenatal diagnostic techniques between 2011 and 2019. A total of 832 invasive techniques were performed. Perinatal results are compared with a control group of pregnant women (n = 1734).ResultsThe early foetal loss rate for the different techniques were 1.1% for amniocentesis, 1.6% for transvaginal chorionic biopsy and 5% for abdominal chorionic biopsy, with a total rate of 1.1%, without statistically significant differences between them (P = .57). We found differences in foetal outcome, in terms of variable early foetal loss, related to the attempts made (when three attempts were made, the risk increased). When comparing the perinatal outcomes after delivery of the group that underwent techniques with the control group, a higher rate of caesarean sections was found in the study group (28.9% vs 20.5%), in addition to lower mean gestational age at delivery (38.33 vs. 38.95 weeks).DiscussionWhen the invasive technique is performed at the right time and with no more than two attempts, we consider that the risk of foetal loss is not affected, and is equal to that of the general population.     

Managing the difficult case of fetal anemia

Objectives.?To describe a series of complex fetal anemia cases, detail the appropriate investigations and management, and review the literature.

Methods.?Four cases of non-red cell alloimmunization or infective cases of fetal anemia are presented.

Results.?Of the four cases presented, one was a neonatal death, one pregnancy was terminated, one case was diagnosed with Diamond Blackfan anemia, and one case was due to recurrent feto-maternal hemorrhages despite negative Kleihauer tests.

Conclusions.?Non-alloimmune causes of fetal anemia can be difficult to manage. Some cases require repeated and frequent intrauterine transfusions. The perinatal mortality and preterm delivery rates are increased, and some cases require considerable long-term treatment including regular transfusions. We present our experience of a series of non-immune fetal anemia managed in a tertiary unit, review the literature, and suggest appropriate management.     

Elevated maternal serum-free β-human chorionic gonadotropin (β-hCG) and reduced risk of spontaneous preterm delivery*

Objective: To evaluate the relationship between first and second trimester maternal serum-free β-hCG and the risk of spontaneous preterm delivery (PTD).

Study design: This was a case-control study of women evaluated and delivered at our institution from 2011 to 2015. Spontaneous PTD was defined as delivery before 37 weeks due to spontaneous preterm labor or premature rupture of membranes. Patient with multifetal gestation and those with medically indicated term or PTD were excluded.

Results: Of 877 women meeting the inclusion criteria, 173 delivered preterm and 704 delivered at term, and 8.1% had high free β-hCG in one or both trimesters. High maternal first and/or second trimester free β-hCG (≥95th percentile) was associated with lower rates of PTD. Thirty-two women with high free β-hCG in both first and second trimesters delivered at term. Gestational age at delivery and birth weights were lower in women who did not have high free β-hCG in any trimester. Low free β-hCG (≤5th percentile) in either trimester was not associated with an increased or decreased likelihood of PTD. Logistic regression demonstrated an independent association of high free β-hCG (≥95th percentile) with a reduced likelihood of PTD. Stratified analysis revealed a stronger impact of this association in women with no prior history of PTD.

Conclusions: High free β-hCG, in the absence of risk factors for medically indicated PTD, is associated with a reduced likelihood of spontaneous PTD and may represent a marker indicating lower risk.     

Cytogenetic confirmation of a positive NIPT result: evidence-based choice between chorionic villus sampling and amniocentesis depending on chromosome aberration

It has been shown that in non-invasive prenatal testing (NIPT) there is a small chance of a false-positive or false-negative result. This is partly due to the fact that the fetal cell-free DNA present in maternal plasma is derived from the cytotrophoblast of chorionic villi (CV), which is not always representative for the fetal karyotype due to chromosomal mosaicism. Therefore, a positive NIPT result should always be confirmed with invasive testing, preferably amniocentesis, in order to investigate the fetal karyotype. However, since this invasive test can only be safely performed after 15.5 weeks of gestation while NIPT can be done from the 10^th week of gestation, this potentially means an unacceptable long waiting time for the prospective parents to receive a definitive result. Based on our experience with cytogenetic investigations in CV and the literature, we determined whether CV sampling may be appropriate for confirmation of an abnormal NIPT result.     

Emotional reactivity to war stressors: An experience sampling study in people with and without different psychiatric diagnoses

There is a lack of knowledge regarding real-time emotional reactivity to high-intensity stressors, particularly in people with mental illness, a potentially vulnerable population. The current study aimed to examine negative emotional reactions to recurring high-intensity stressors within a continuous war situation, in people with different psychiatric diagnosis types. Experience sampling method was used to examine emotional reactions among 143 civilians exposed to rockets during the 2014 Israel–Gaza war, of them 18.2% with psychosis, 14.7% with anxiety or depression and 67.1% without mental illness. Participants reported exposure to rocket warning sirens and the levels of 10 negative emotions twice a day for 30 days. Negative emotional levels were higher on most emotions following high-intensity stressors (sirens), that is, emotional reactivity was demonstrated in real-time during war. Overall, no difference in reactivity was found among the three study groups. Moreover, people with anxiety/depression were less reactive than people without mental illness on sadness and being overwhelmed. The findings indicate similar and sometimes lower emotional reactivity to high-intensity stressors in people with mental illness compared to the general population. Nevertheless, people with mental illness seem to have significant emotional needs during war, to be addressed in prevention and intervention efforts.