Cognitive and behavioral abnormalities in children whose mothers smoked cigarettes during pregnancy.
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Biomedical subjects
Publications and source records attributed to R L Naeye.
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Data were analyzed from 26,886 pregnancies to determine whether coitus is involved in the genesis of amniotic-fluid infections. The frequency of infection was 156 per thousand births when mothers reported coitus once or more per week during the month before delivery, versus 117 per thousand when no coitus was reported (P less than 0.001). The percentage of infected infants who died was 11.0 when there was coitus versus 2.4 when there was no coitus (P less than 0.001). The frequencies of low Apgar scores, neonatal respiratory distress, and hyperbilirubinemia were about doubled when mothers reported coitus. The coitus-associated effects were greater in preterm than in fullterm infants. The pregnancies in the study took place between 1959 and 1966, when national perinatal mortality rates were higher than they are now. Deaths from coitus-associated infections may be less frequent today.
This study determined the relationship of maternal weight gain in pregnancy to its outcome. Mothers who were overweight at the start of pregnancy had the fewest fetal and neonatal deaths with a 16 pound weight gain at term. The optimal weight gain for normally proportioned mothers was 20 pounds and for underweight mothers 30 pounds. For all three groups perinatal mortality rates increased with weight gains less or more than these optimal values. Very low or very high pregnancy weight gains had only a modest influence on the frequency of common placental and fetal disorders. However, once one of these disorders was established, mortality rates from it usually increased severalfold when mothers had very low or very high weight gains.
The effect of diet supplementation throughout pregnancy on third-trimester amniotic fluid growth-supporting activity (GSP) was studied in 100 African women; 32 were given zinc supplementation, 22 each animal and vegetable supplements, respectively, and 24 served as control subjects. No difference in GSP was noted in any of the four groups, the majority of fluids (65%) being noninhibitory. Zinc levels in fluids from African women were much lower than those described for other population groups at corresponding periods of gestation. Although zinc levels in liquor rose following dietary zinc supplementation, these remained lower than values described in white patients. In vitro addition of zinc (up to 153 mu moles per liter final concentration) to 17 noninhibitory African liquors resulted in these fluids becoming inhibitory.
The study was undertaken to determine the causes of the more frequent pre-term deliveries, fetal and neonatal deaths associated with maternal urinary-tract infections during pregnancy. The combined perinatal mortality rate for eight common placental and fetal disorders was 42 per thousand births in the infected vs. 21 per thousand in the noninfected, owing to a greater mortality from noninfectious placental and fetal disorders in the gestations with the urinary-tract infections (P less than 0.001). All the mortality excess took place when the urinary-tract infections occurred within 15 days of delivery. Death rates were highest when the urinary-tract infections coexisted with maternal hypertension and acetonuria.Hydramnios, amniotic-fluid bacterial infections and abruptio placentae were responsible for two thirds of the more frequent preterm deliveries in the pregnancies complicated by urinary-tract infections.
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A number of maternal factors strongly influence the development and outcome of fetal infections. Severely undernourished mothers produce neonates with evidence of an immunoincompetence that persists into later childhood. Mothers who fast during pregnancy develop metabolic acidosis much more rapidly than non-pregnant women. The metabolic acidosis leads to high fetal and neonatal death rates from a variety of pre-existing disorders, including infections. Such metabolic acidosis also appears responsible for the excessive fetal and neonatal deaths associated with maternal urinary tract infections. Finally, coitus during pregnancy markedly increases both the frequency of bacterial infections of amniotic fluid and the mortality due to them. The effects are greatest at mid-pregnancy and gradually decrease to term.
Amniotic fluid infections manifested by an inflammatory response in the extraplacental membranes and subchorionic plate of the placenta are a common phenomenon thought to be due in most cases to ascending bacterial infections via intact membranes. Fatal spread to the fetus is much less common and more likely to occur in underprivileged communities. The probable reasons are nutritional deprivation in the mother or both, leading to production of a liquor with diminished ability to suppress bacterial growth. Zinc is one component of the antibacterial system but liquor levels of zinc vary widely and inconsistently with antibacterial activity. Dietary supplementation with zinc did not improve antibacterial activity of liquors in a population with diminished liquor antibacterial activity and large number of fatal infections. Other factors in the genesis of amniotic fluid infections may be interference with normal defence mechanisms as a result of coitus in late pregnancy and vaginal infections with Trichomonas vaginalis. Socioeconomic factors may play a role apart from their association with maternal nutrition, through diminished hygiene associated with insufficient use of water and insufficient availability and use of medical facilities.
Data from a large prospective study of pregnancy were used to determine whether the number of years a mother had smoked cigarettes influenced the development of common fetal and placental disorders. Three disorders increased in frequency when mothers had smoked for more than 6 yr: placenta previa +143%, abruptio placentae +72% and large placental infarcts +37% (all P less than 0.05). Mothers' current smoking habits had a smaller influence on the frequency of these disorders, and the effects of smoking were largely independent of maternal pregnancy weight gain. The placentas of smokers had microscopic evidences of underperfusion from the uterus. The placental abnormalities were influenced by both the number of years mothers had smoked and by their current smoking habits.
The newborn infant with a congenital diaphragmatic hernia (CDH) who develops severe respiratory distress requiring operative repair within the first 24 hours of life represents one of the most challenging problems in pediatric surgery. The mortality in these infants still exceeds 50% and has historically been attributed to ventilatory insufficiency secondary to pulmonary hypoplasia. However, the primary abnormality in these neonates seems to be an increase in pulmonary vascular resistance with an elevation of pulmonary artery pressure, right-left ductal shunting, preductal shunting and progressive hypoxemia. Eighteen neonates with a CDH were operated upon within the first 24 hours of life with a mortality of 38%. In no instance did ventilatory insufficiency seem to be a major factor in the death of the patient. Seven infants with progressive hypoxemia were treated with a vasodilator, tolazoline. Six of the seven infants showed an initial response to treatment, with a rise in preductal PaO2 and a decrease in ductal shunting. Four of these seven desperately ill neonates survived. Pathologic examination of the pulmonary vasculature in the non-survivors revealed an increase in muscle mass within the pulmonary arterioles. An exaggerated vasoconstrictive response of an abnormally hypertrophied pulmonary vascular bed leading to an elevation of pulmonary vascular resistance, rather than abnormalities of ventilation, appears to be the important mechanism leading to the often fatal hypoxemia observed in the neonate with a CDH. Improved survival will depend upon the successful management of the deranged pulmonary vascular hemodynamics seen in these infants.
Data from a large study were used to determine the frequency of fatal disorders associated with low Apgar scores. 5-min scores had the best correlation with mortality rates. Death rates were more than ten times greater with abnormal than with normal 5-min scores. This difference was only 3-fold for 1-min values. Amniotic fluid infections were responsible for nearly half of the deaths in preterm and 24% of the deaths in term neonates with 5-min Apgar scores 0--6. The respective values for disorders that cause antenatal hypoxia were 25 and 24% and for major congenital anomalies, 7 and 28%.
Abruptio placentae was a common cause of perinatal death in Addis Ababa, Ethiopia in 1974-1975 with a frequency of 5.5/1000 births. This disorder had its peak frequency at term. No abnormalities were found in the placentas to explain the placental abruptions but there were other clues to their genesis. There was a strong association of the fatal abruptions with severe poverty in the mothers. These poor mothers were both undernourished and malnourished during pregnancy. Their fetuses and neonates who died had multiple evidences of undernutrition including a relative undergrowth of adrenals, spleens and livers and a relative acceleration of lung maturation. These findings support observations in more prosperous nations that poor nutrition of the gravida may have an important role in the genesis of abruptio placentae.
This study attempted to identify the factors that are most important in establishing accurate pregnancy due dates. It quantitated the influence of many factors that affect the duration of pregnancy, as calculated from the last menstrual period, with data from a large prospective study. To limit the influence of maternal constitutional factors, analyses were conducted on the differences between the durations of repeat pregnancies in the same mothers. The mean difference between the calculated durations of successive pregnancies in 4,599 mothers was 18 days. This difference was reduced to 10 days when the pregnancies had been planned and the dates of the last menstrual period had been recorded in the first trimester of pregnancy. Many other factors, including maternal and fetal disorders, significantly altered the length of individual pregnancies but had no significant influence on the overall duration of pregnancies in the study.
Data from a prospective study of 50,826 neonates were used to determine the frequency and significance of disorders related to apnea in newborns. Such apnea proved to be a significant prognosticator for neonatal death. Fifty-eight percent of preterm neonates with multiple apneic episodes and 18% with a single episode died, whereas only 6% of those without recorded apnea died. The rates were 44%, 5%, and 1% for full-term infants. Amniotic fluid infection was the underlying disorder in 35% of the preterm and 25% of the term neonates who had multiple episodes of apnea. A third of the preterm and 25% of the term infants who had such apneic episodes had antecedent hypoxia-related disorders, i.e., abruptio placentae, erythromblastosis fetalis, placenta previa, large placental infarcts, and umbilical cord compression. Among the apneic neonates, those who were infected were twice as apt to die as were those who had hypoxia-related disorders. Hypoplasia of the lungs and easily recognized central nervous system malformations were responsible for most of the apnea-related deaths associated with congenital malformations.
The perinatal mortality rate in a large U. S. study was 139 per 1,000 births for twins and 33 per 1,000 for singletons. Sixteen per cent of the twin deaths were due to amniotic fluid infections, 11 per cent to premature rupture of the membranes, 8 per cent to the monovular twin transfusion syndrome, 8 per cent to large placental infarcts, 7 per cent to congenital anomalies, and the rest to over 20 other disorders. The perinatal mortality rate for monozygotic twins was 2.7 times that for dizygotic twins, mainly due to more amniotic fluid infections, congenital anomalies, and the twin transfusion syndrome in the monozygotic pairs. To study the role of poor maternal nutrition on twins, a similar study of perinatal mortality rates was undertaken in Addis Ababa, Ethiopia. Addis Ababa twins had 2.5 times the mortality rate of U. S. twins, mainly due to a higher frequency of amniotic fluid infections, abruptio placentae, cord accidents, obstructed labors, congenital syphillis, and the twin transfusion syndrome in the Ethiopians.
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Placental growth retardation caused 84 fetal and neonatal deaths per 100,000 births. Its frequency increased as mothers' diastolic blood pressure levels increased, an effect augmented by proteinuria. The perinatal deaths also increased with advancing maternal age, anemia, and poverty. Maternal weight gains were low in the involved pregnancies, and the fetuses and neonates who died had a pattern of growth retardation characteristic of fetal undernutrition. Microscopic abnormalities in the decidua and placenta were characteristic of inadequate perfusion of the placenta from the uterus. They included fibrinoid changes in the arteries and arterioles of the decidua, villous cytotrophoblastic hyperplasia, and an obliterative endarteritis in fetal stem arteries of the placenta.
The study sought to determine what proportion of the perinatal mortality excess associated with prolonged gestations was due to placental insufficiency. Using data from a large prospective study of pregnancy, the perinatal mortality rate was 20.9/1000 births for post-term and 11.7/1000 for term infants. Only a quarter of the perinatal mortality rate excess in the post-term pregnancies was due to disorders related to inadequate uteroplacental perfusion, i.e., abruptio placentae, large placental infarcts and marked placental growth retardation. Twenty-six per cent of the mortality excess was due to congenital malformations, 19% to amniotic fluid infections, 8% to Rh erythroblastosis fetalis and the remaining 22% to a variety of other disorders. The post-term mortality excess due to congenital malformations was in infants who had hypoplastic adrenal glands, a well-known cause of prolonged gestation. The 4205 placentas of the post-term infants did not show any significant increases in those microscopic lesions that are characteristic of uteroplacental under-perfusion.