Ricardo Schwarcz

Arterial blood pressure standards during normal pregnancy and their relation with mother-fetus variables

The purpose of our work was to study blood pressure variations during pregnancy in a normal Latin American population from Argentina and Uruguay; to investigate blood pressure variations according to maternal age, parity, or pregnancy weight gain; and to correlate diastolic blood pressure levels in the last trimester of pregnancy with newborn birth weight. This prospective study included follow-up throughout gestation of 249 normal pregnant women (129 nulliparous and 120 multiparous) with a weekly blood pressure control under the same experimental conditions. Our results demonstrate that there is only a low correlation between maternal age and diastolic blood pressure, but no correlation was found with systolic blood pressure; maternal weight gain correlates with blood pressure changes; no correlation was found between gestational age and blood pressure, although an increasing tendency in systolic and diastolic blood pressure was found toward the end of gestation; and a significant correlation was observed between birth weight and average diastolic blood pressure during the third trimester. These findings demonstrate the potential significance of the use of standard blood pressure data from normal pregnant women for the future clinical evaluation of our population.

Small for Dates: Evaluation of Different Diagnostic Methods

Ninety‐four high‐risk pregnancies were studied weekly in a prospective and longitudinal study. Uterine height, biparietal diameter (BPD), cranial perimeter (CrP) and abdominal perimeter (AbP) were measured. Amniotic fluid volume (AFV) was assessed. Of the sample selected, 58 neonates were appropriate for gestational age and 36 were small‐for‐date (17 symmetrical and 19 asymmetrical). The sensitivity values in diagnosis of small‐for‐dates were: 67% for BPD, 42% for CrP, 94% for AbP, 56% for Uterine Height and 28% for AFV. The specificity for the five variables ranged from about 91% to 100%. If we consider symmetrical and asymmetrical retardation separately, the sensitivity values for the former were: 94%, 77%, 100%, 77% and 24% for BPD, CrP, AbP, Uterine Height and AFV respectively. For symmetrical retardation, the sensitivity values were: 43%, 11%, 90%, 37% and 32% for BPD, CrP, AbP, Uterine Height and AFV respectively. The fetal cranial measurements were the only ones to demostrate a different pattern of evolution in symmetrical and asymmetrical small‐for‐dates. This is therefore a useful measurement in making a differential diagnosis between both retardations. The earliest diagnoses were made in the symmetrical small‐for‐date group.

Phosphatidylglycerol determination in the amniotic fluid from a PAD placed over the vulva: a method for diagnosis of fetal lung maturity in cases of premature ruptured membranes.

Four hundred and forty seven pregnant women with ruptured membranes, were prospectively studied in order to assess the diagnostic capacity of Phosphatidylglycerol (PhG) determination in amniotic fluid recovered from vulval pads in the diagnosis of Hyaline Membrane Disease (HMD). The identification of PhG was performed using one dimensional silica gel thin layer chromatography. The sensitivity of PhG determination in the diagnosis of HMD in newborns of the total population was found to be 88.2%, with a specificity of 76.9%. In the study population, the incidence of HMD was 7.6%, the negative predictive value was 98.8% and, the positive predictive value was 24.0%. When the 265 newborns of the gestational age group of less than or equal to 34 weeks is considered, we observed an incidence of HMD of 12.1%. The diagnostic capacity of PhG in this group was shown by a sensitivity of 87.5%, a specificity of 76.4%, a positive predictive value of 33.7% and a negative predictive value of 97.8%. This method of assessment of fetal lung maturity has a diagnostic capability similar to that described by other authors, who used amniotic fluid obtained vaginally or transabdominally. The procedure described here of amniotic fluid collection is non-invasive, harmless to the mother and fetus and simple to perform. The characteristics of this method, allow serial studies of the amniotic fluid to be carried out.

EFFECT OF CERVICAL DILATATION UPON MILK EJECTION IN HUMANS AND ITS RELATION TO OXYTOCIN SECRETION.

Abstract The effect of cervical dilatation on milk ejection was studied in puerperal women. The milk-ejecting effect was estimated by the recording of intramammary pressure. The cervix was dilated by means of a plastic balloon. In 8 of our 9 cases milk ejection could not be induced, despite the fact that the gland responded normally to oxytocin administration. Only in exceptional cases can oxytoxin secretion be induced as a result of cervical dilatation, and in those cases the quantity released is minimal.

Maternal mortality in Latin America and the Caribbean

Mortality and serious morbidity as a result of childbirth not only cause human suffering but they also have implications for the social and economic development of a society. In less-developed countries economic development is hindered by high rates of maternal neonatal and infant deaths. These deaths which affect socially deprived sections of society are associated with malnutrition low levels of education poverty and poor access to health-care services. Initiatives are needed for Latin American and Caribbean countries to reduce maternal mortality to the targeted rate of 15.6 per 100000 live births which rate Costa Rica has already achieved. Local programs need to be intensified to improve the basic development of socially excluded communities. Health-related interventions are also needed to control the biological factors associated with maternal mortality. Moreover evidence indicates that the majority of causes of high maternal mortality can be prevented by simple and low-cost interventions.

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)