Fernando Nieto

Ultrasonic patterns of intrauterine fetal growth in a Latin American country

Head circumference and its cross-sectional area, biparietal and fronto-occipital diameters, abdominal circumference and its cross-sectional area, and the transverse and anteroposterior diameters were measured in 30 healthy single fetuses from normal pregnancies by means of ultrasound. The 5th, 50th and 95th percentiles of distance and velocity curves are described. The comparison of the values of a perimeter (abdominal or cephalic) measured directly from the photograph or calculated by the ellipse formula, showed a straight correlation. The use of the ellipse formula in current practice may simplify and reduce the cost of this technology.

Early postnatal growth evaluation in full-term, preterm and small-for-dates infants

Postnatal growth patterns of weight, length/height and head circumference in full-term (FTI), preterm (PTI) and small-for-dates (SFDI) infants, are described by using distance and velocity data together with the concept of growth per unit of body weight. The study was performed in 112 healthy Caucasian infants, of a similar socioeconomic status, in Montevideo, Uruguay. Median growth velocity (MGV) and median growth velocity per unit (MGVU) of body size are defined. The authors stress that: (a) growth velocity is related to body mass, (b) a useful evaluation of growth is made by using two consecutive measures with a certain time interval independently of birthweight and gestational age, and (c) expressing growth per day per unit relates well to daily nutritional and other requirements.

Oxygen transport in newborns at different gestational ages

Oxygen (O2) transport was assessed through the affinity between O2 and hemoglobin (Hb) in 123 newborns of 28 to 40 week gestational ge, with a minimum of 9 newborns for each gestational age group (see table). In order to assess the O2-Hb affinity, we studied the correlation between the pO2 and the Hb saturation for each gestational age, obtaining estimates of the oxy-hemoglobin dissociation curves corresponding to each gestational age (see fig. 3). The pO2 levels corresponding to the 50% saturation (P50) for each gestational age were estimated from there. All newborns were from single vaginal deliveries with no fetal distress before birth and with an adequate weight for gestational age. The latter was calculated according to the date of the last menstrual period (78% of the cases), echography (10.6% of the cases) or neonatal physical exam (11.4% of the cases). A P50 vs. gestational age linear regression showed a high determination rate (r2 = 0.957, p less than 0.00001) (see fig. 2) which supports the hypothesis of the P50 linear growth; decrease in the Hb-O2 affinity with increasive gestational age (Hb-O2 affinity is different in newborns of different gestational ages). With these results one may conclude that the Hb-O2 uptake varies according to gestational age (P50 changes linearly as gestational age increases) and that a single measurement of pO2 in a newborns, blood does not accurately evaluate the amount of O2 that is transported to the tissues, because the transport capacity depends, among other factors, upon gestational age. The Hb saturation better represents the amount of O2 that can get to the cell level.(ABSTRACT TRUNCATED AT 250 WORDS)