Evaluación de un programa de intervención prenatal en embarazadas con fetos pequeños para la edad gestacional

La prematuridad y el retraso de crecimiento intrauterino constituyen actualmente los problemas más importantes de la Medicina Fetal y de la Neonatología y son las causas más frecuentes de la morbilidad y mortalidad perinatal en los países desarrollados. OBJETIVO. Valorar la eficacia de un programa de intervención de apoyo prenatal (creado ex-novo) dirigido a madres gestantes de fetos Pequeños para la Edad Gestacional (PEG): detectar si este procedimiento mejora el desarrollo físico y neuroconductual del neonato, el estado emocional de la madre y el vínculo entre ambos. METODOLOGÍA. Estudio quasiexperimental tipo ensayo clínico controlado y sin asignación aleatoria de la intervención realizado en el área Materno-fetal de BCNatal (corporación del Servicio de Medicina Maternofetal del Hospital Clínic y el Hospital Sant Joan de Déu de Barcelona). El tamaño final de la muestra fue de 158 embarazadas, de las cuales 65 formaron parte del grupo intervención y 93 formaron parte del grupo control. RESULTADOS. Al finalizar el programa se observa que el feto y el neonato muestran una mayor ganancia de peso y mayor perímetro craneal en el grupo intervención. En cuanto a las capacidades y competencias del neonato, valoradas con la Escala de Brazelton, los del grupo intervención obtienen unos resultados discretamente superiores en casi todos los parámetros estudiados, destacando una mayor capacidad de habituación ante los estímulos auditivos. En relación a la embarazada, los resultados más relevantes al finalizar el programa son una disminución de la ansiedad (valorada con el cuestionario STAI) y una mayor vinculación afectiva materno-filial (valorada con la escala EVAP). CONCLUSIONES. Para las madres gestantes de fetos PEG, el hecho de haber participado en un programa de intervención de apoyo prenatal tiene un resultado beneficioso para ambos, madre e hijo, presentando menos ansiedad materna, mejores condiciones para establecer el vínculo así como una mejora en el desarrollo físico e indicios de mejores capacidades neuroconductuales en el neonato.Prematurity and intrauterine growth restriction are currently the most important problems in Fetal Medicine and Neonatology and also are the most frequent causes of perinatal morbidity and mortality in developed countries.The Objectives were to evaluate the effectiveness of a prenatal support program (created ex-novo) aimed at pregnant mothers of small fetuses for Gestational Age (PEG): to detect if this procedure improves the physical and neurobehavioral development of the neonate, the emotional state of the mother and the bond between them. This was a quasiexperimental study of a controlled clinical trial and without random assignment of the intervention performed in the Maternal-fetal area of BCNatal (Hospital of the Maternal-Fetal Medicine Service of Hospital Clínic and Sant Joan de Déu Hospital in Barcelona). The final sample size was 158 pregnant women, of whom 65 were part of the intervention group and 93 were part of the control group. At the end of the program, it is observed that the fetus and the neonate show a greater weight gain and greater cranial perimeter in the intervention group. As for the abilities and competences of the newborn, evaluated with the Brazelton Scale, those in the intervention group obtained slightly better results in almost all the studied parameters, emphasizing a greater capacity of habituation before the auditory stimuli. In relation to the pregnant woman, the most relevant results at the end of the program are a reduction of anxiety (valued with the STAI questionnaire) and a greater maternal-filial affective attachment (valued with the EVAP scale). In conclusion, for pregnant mothers of PEG fetuses, having participated in a prenatal support intervention program has a beneficial outcome for both mother and child, with less maternal anxiety, better bonding conditions, and improved development physical and signs of better neurobehavioral abilities in the neonate

Centering performance of the model agrees with experimental data from real bees for <i>F</i> = 0.0 and 0.25.

<p>Experimental data is from Dyhr et al [<a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1004887#pcbi.1004887.ref003" target="_blank">3</a>]. One wall was held at a constant spatial frequency while the other is varied, with square wave and sinusoidal patterns.</p

Centering performance of the model with <i>F</i> = 0.0 and <i>F</i> = 0.25 both agree with experimental data, while performance with <i>F</i> = 0.5 does not.

<p>Experimental data are from Dyhr et al [<a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1004887#pcbi.1004887.ref003" target="_blank">3</a>] for real bees. One wall is held at a constant spatial frequency while the other is varied with sinusoidal patterns. Dashed lines indicate the two points where the spatial frequencies of the two walls are equal, one for each of the two lines. The model error bars show the variance of two runs with differing starting positions in the corridor.</p

Reichardt-Hassenstein detector.

<p>The detector tests whether input at the two locations (top) is correlated in time, with peak response at the time constant <i>τ</i>. M represents multiplication, and—represents subtraction. By taking the difference between the progressive and regressive circuits (in this case the right arm is progressive and the left arm is regressive) the detector gives a response (bottom) from -I to +I, where I is the maximum input to the detector, and a negative value indicates a reverse correlation. The architecture of this detector forms the basis of the retinotopic layers of the model, however the form is modified by the addition of neural dynamics on both arms of the detector. Further details can be found in the text.</p

Layout of the full system showing subregions and AVDU placements.

<p>The input to the full system consists of 32x32 ommatidial locations (blue grid), which are processed by AVDUs in three subregions, left (green), right (red) and centre (orange). AVDUs (yellow circles) exist between the location pairs sharing the edge they are located on. The preferred motion direction of each subregion is shown with an arrow. Note that the 32x32 extent of the locations covers a field of view extending 260 degrees horizontally and 180 degrees vertically.</p

The average responses of the full detector to different spatial frequencies and different contrasts.

<p>The input has a spatial frequency of 19°, and the model <i>F</i> = 0.25. The response shows a clear velocity tuning that is largely invariant to the spatial frequency or contrast of the stimulus, with the exception of very low and high values of AV where there is greater variance.</p

The two versions of the AVDU detector. Left: with dynamic time constants; right: with delays.

<p>Squares indicate LIN units, circles indicate other operations. In the centre we suggest the corresponding regions of the bee visual system for each stage of the detector. In both versions the input is first temporally filtered in the input layer (first square), then is transmitted to two Reichardt-Hassenstein detectors (<a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1004887#pcbi.1004887.g001" target="_blank">Fig 1</a>). These either differ in the time constants of the LINs (τ₁ and τ₂) or by fixed delays (d₁ and d₂) shown with gray backgrounds. A base time constant of τ_b = 1ms is used otherwise. A further LIN is used to apply the subtraction, having a time constant of τ_R = 5ms, and then the division is performed in the final LIN following summation across all detectors in the array. This final LIN has a time constant of τ_S = 100ms to smooth the output.</p

Comparison of the responses of dynamic time constant variants of the detector.

<p>(A) For a fixed time constant (τ₁) and varying long time constant (τ₂). (B) for a fixed long time constant (τ₂) and varying short time constant (τ₁). A best match to log-linear response for the 5/15ms time constant pair is found. All responses shown are for the detector responding to offsets only. The desired log-linear response is shown by the gray line.</p

Example of fits to one data set from Ibbotson 2001.

<p>f(x) (response versus angular velocity) for log, linear and exponential fits are shown with their <i>R</i>² values.</p

Odometry using the flight of the model bee.

<p>The simulated bee was flown in the for 5 seconds with the same stimuli on both walls. The stimuli were square wave gratings with spatial frequencies from 0.1 to 0.8 cycles per degree when observed from the corridor centre. Post-simulation the distance in cm per unit of the summed logged detector output is compared, and shows a consistent estimation of distance from the total summed detector output until 0.6 cycles per degree.</p