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Biomedical subjects

D P Misra

Publications and source records attributed to D P Misra.

At least 19 recordsLinked to original sources
PubMed2001

Rates of preterm delivery among Black women and White women in the United States over two decades: an age-period-cohort analysis.

The authors assessed the influence of age, period, and cohort effects on rates of preterm delivery in the United States. Rates of preterm delivery for singleton births (<37 weeks) in seven age groups (15-19, 20-24,., 45-49 years), five periods (1975, 1980, 1985, 1990, 1995), and 11 maternal birth cohorts (1926-1930, 1931-1935,., 1976-1980) were examined. Over the 20-year study interval, preterm delivery increased by 3.6% among Blacks (from 15.5% in 1975 to 16.0% in 1995) and by 22.3% among Whites (from 6.9% to 8.4%). Among Black primigravid women, rates of preterm delivery increased from 1975 to 1990 and began to decline thereafter; among Whites, the rates increased between 1975 and 1995. In Blacks, women aged 25-29 years had the lowest rates for the first and second births, and women aged 30-34 years had the lowest rate for subsequent births. In Whites, the age groups with the lowest preterm delivery rates were 20-24 years for first births and 25-29 years for subsequent births. Cohort-specific rates of preterm delivery remained fairly constant across age strata and periods for Whites, but a small trend was apparent for Blacks aged 30-44 years. The consistency of the observed age effects across periods and cohorts suggests that the age effect is partly due to biologic factors. The presence of period effects might be linked to the increased survival of premature infants or to increased viability among births occurring at lower lengths of gestation.

Adolescent↗
PubMed2001

Testing a sociomedical model for preterm delivery.

The study purpose was to contribute to the development of a model for preterm birth that brings together social, psychosocial and biomedical factors. The three research questions were: (a) Which social and psychosocial factors influence the risk of preterm delivery? (b) Are the effects of social and psychosocial factors independent? (c) Do the biomedical factors identified and measured here explain the effect of social and psychosocial factors? The sample comprised 739 low-income black non-Hispanic women. Interviews were conducted after delivery, and medical records were abstracted. Nearly a quarter of the women delivered preterm (23.5%). Two social factors strongly predicted risk of preterm delivery: inadequacy of time and money for non-essentials. The effect of both was stronger than expected from each alone and was partially mediated by psychosocial factors. Several psychosocial factors also predicted preterm delivery risk but only stress and locus of control were independent predictors. With the inclusion of biomedical factors, stress (OR = 1.86, P = 0.005) and locus of control (OR = 1.75, P = 0.007) continued to be strongly associated with preterm delivery. The effect of inadequate resources for non-essentials was no longer significant, suggesting mediation. These strong effects of social and psychosocial factors should be examined in future studies.

Adolescent↗
PubMed1999

Risk factor profiles of placental abruption in first and second pregnancies: heterogeneous etiologies.

The objective of this study was to identify risk factors for placental abruption in first and second pregnancies and to compare the risk-factor profiles for evidence of etiologic heterogeneity. A prospective cohort design was used. The study took place at university-based medical centers that participated in the U.S. Collaborative Perinatal Project (1959-1965). A total of 10,774 first pregnancies only and 6529 first and second pregnancies of women were enrolled in the study. Participation rate was 96%. All pregnancies were selected at some centers, whereas other centers used either random or systematic sampling. The main outcome measure was placental abruptions in first and second pregnancies. The placental abruption rate was 1.7% (n = 182) for first and 2.2% (n = 143) for second pregnancies. Prior abruption increased risk in second pregnancies significantly (odds ratio [OR] = 3.2, 95% confidence interval [CI]: 1.7-5.8) after adjusting for other risk factors. Placental infarcts and smoking duration were associated with an increased risk for abruption in second but not first pregnancies. Effect of placental infarcts was modified by gestational age with strongest risk for abruption at shortest gestations. For each year of smoking prior to pregnancy, risk of abruption increased 40% (OR = 1.4, 95% CI 1.0-1.8). Etiologies of placental abruption for first and second pregnancies were different, indicating heterogeneity in their risk-factor profiles. Future research would best consider abruption as a heterogeneous complication to further knowledge of its etiology.

Abruptio Placentae↗
PubMed1999

Environmental tobacco smoke and low birth weight: a hazard in the workplace?

Low birth weight (LBW) increases infant morbidity and mortality worldwide. One well-established risk factor is maternal smoking. Environmental tobacco smoke (ETS) exposure has recently been focused on as another potential risk factor. In this article, we review epidemiologic literature on the effects of ETS on LBW and intrauterine growth retardation (IUGR), the cause of LBW related to maternal smoking. As we consider the feasibility of modifying women's exposure, we focus our discussion on workplace exposure to ETS. The workplace is particularly important to consider because women of child-bearing age are present in the workplace in greater numbers now than ever before. In addition, certain subgroups of working women may be particularly at risk from the effects of ETS on pregnancy because they work in environments with higher exposure or they are more susceptible to its effects. We conclude that there is consistent evidence to relate maternal ETS exposure to an increased risk of adverse pregnancy outcomes and that this association may be generalized to the work environment. In studies with positive findings, infants exposed to ETS antenatally were 1.5-4 times more likely to be born with LBW, but few studies examined LBW. Most studies looked at measures of IUGR. ETS was associated with reductions in birth weight (adjusted for gestational age) ranging from 25 to 90 g. Infants born to women exposed to ETS were generally 2-4 times more likely to be born small-for-gestational age. ETS exposure in the workplace can and should be minimized to protect pregnant women from its adverse effects.

Adult↗
PubMed1998

Effects of physical activity on preterm birth.

The authors conducted a cohort study of low income women to determine the effect of physical activity on the risk of preterm birth. Women were sampled prenatally from four clinic sites and were scheduled for delivery at the University of Maryland Medical Systems (UMMS). Women who delivered infants at UMMS but who had received no prenatal care were also eligible. Preterm delivery was defined as a delivery prior to 37 completed weeks gestation. After adjusting for confounders, the odds of preterm delivery were increased for women who climbed stairs > or = 10 times per day (odds ratio (OR) = 1.60, 95% confidence interval 1.05-2.46) and for women who engaged in purposive walking > or = 4 days per week (OR = 2.10, 95% CI 1.38-3.20). Leisure-time exercise (> or = 60 days in the first and second trimesters combined) had a protective effect on preterm delivery (OR = 0.51, 95% CI 0.27-0.95). Television viewing had a U-shaped relation with preterm delivery (ORs (95% CI): < 15 hours, 2.09 (1.21-3.61); 29-42 hours, 1.50 (0.84-2.67); > 42 hours, 3.05 (1.75-5.40)). While the results support current recommendations regarding leisure-time activities, activities of daily living appear to increase risk of preterm delivery among low income women. These findings and those for television watching warrant further investigation.

Activities of Daily Living↗
PubMed1997

The association between nulliparity and gestational hypertension.

The association between nulliparity and gestational hypertension was examined by analysis of the 1988 National Maternal and Infant Health Survey. Gestational hypertension was defined as the occurrence of two consecutive diastolic blood pressure readings > or = 90 mm Hg after 20 completed weeks gestation in the absence of proteinuria in subjects normotensive prior to pregnancy. Preeclampsia was defined as gestational hypertension in the presence of significant proteinuria. Using logistic regression, 110 subjects with gestational hypertension and 34 subjects with preeclampsia were compared with 4371 subjects free of all hypertensive disorders. Nulliparity was weakly associated with an increase in the risk of gestational hypertension among whites (odds ratio, 95% confidence interval: 1.58 [0.92-2.74]) and not associated with risk among blacks (1.09 [0.51-2.35]). Preeclampsia was strongly associated with increased risk among whites (2.86 [0.94-8.73]) and blacks (2.94 [0.94-9.18]). The small increase in risk of gestational hypertension associated with nulliparity in contrast with the large increase in risk of preeclampsia suggests that these disorders may have a different etiology.

Adolescent↗
PubMed1996

The effect of the pregnancy-induced hypertension on fetal growth: a review of the literature.

Understanding how pregnancy-induced hypertension affects fetal growth could suggest a particular biological mechanism leading to intrauterine growth retardation (IUGR) and improve our understanding about how other exposures affect the risk of IUGR. It is hypothesised that hypertension reduces uteroplacental perfusion and through this route inhibits fetal growth. Definitions and associated incidence rates are given. The findings from the epidemiological literature on hypertension in pregnancy and fetal growth are then critically discussed and summarised. Finally, the steps to be taken next in this area of research are outlined.

Eclampsia↗
PubMed1995

The effect of smoking on the risk of gestational hypertension.

Data from the 1988 National Maternal and Infant Health Survey were used to examine the effect of smoking on the risk of gestational hypertension (GH). GH was defined as the occurrence of two consecutive diastolic blood pressure readings of at least 90 mmHg after the 20th week of gestation in the absence of proteinuria in subjects normotensive prior to pregnancy. One-hundred ten subjects with gestational hypertension were compared with 4371 subjects free of all hypertensive disorders. Smoking during pregnancy was associated with a reduction in risk of GH overall (Odds Ratio (95% CI) = 0.18 (0.07-0.43)) and within each race and parity subgroup. When the protective effect of smoking was examined by race, black subjects appeared to benefit less from smoking compared with whites but the weaker effect in blacks was attributable to less smoking by blacks. Parous subjects experienced a larger reduction in the risk of GH associated with smoking than nulliparous subjects and this persisted at each dose level of smoking. Neither the protective effect of smoking nor the difference by parity appeared to be due to confounding by race, age, weight gain, alcohol use or marijuana use (adjusted OR (95% CI): nulliparous 0.28 (0.09-0.94) vs. parous 0.10 (0.03-0.30)).

Adult↗
PubMed1975

Platelet 5-hydroxy-tryptamine in thrombotic and non-thrombotic diseases.

It is generally accepted that platelets from the main constituent of a thrombus. Experimental work has shown that 5-hydroxy-tryptamine (5 HT) in a concentration of 0.06 mg/ml produces clumping of the platelets. In view of this it was decided to estimate platelet 5 HT in thrombotic and non-thrombotic diseases. Thirty-five patients were investigated. Estimations of 5 HT were made on washed platelets rather than platelet-rich plasma which has been used in previous studies. Three groups were recognized on the basis of platelet 5 HT values. The first group consisted of five subjects who were clinically asymptomatic at the time of investigation but died 24 to 48 hours later and were shown at autopsy to have deep-vein thrombosis and pulmonary embolism; they had the highest level of platelet 5 HT. The second group comprised eight patients with cerebral thrombosis whose platelet 5 HT ranged between 1529 and 2183 ng/10-9. There were 22 subjects in the third group (11 apparently normal and 11 with different pathologies). Their platelet 5 HT ranged from 611 to 877 ng/10-9 and did not vary in the different pathological conditions studied. Since the highest level of platelet 5 HT was observed in patients prior to the formation or embolization of a thrombus, it is suggested that this may have some role in initiating thrombus formation.

Age Factors↗
PubMed1975

Albumin metabolism in elderly patients.

Hypoalbuminemia, without any apparent cause, is occasionally seen in elderly patients. Eleven patients (6 with plasma albumin of over 3 gm% and 5 with plasma albumin of 3 gm% or less), who had no evidence of liver disease or nephrosis and whose dietic history suggested that they were taking adequate amounts of protein were investigated, using 131I human serum albumin. None were acutely ill and their age ranged from 70 to 86 years. It was found that elderly subjects with plasma albumin level of 3 gm% or less had significantly reduced albumin pools and an increased fractional catabolic rate. It is suggested that this may be due to an impairment of the control of degradation in these patients. There was no increased gut loss of albumin in 3 hypoalbuminemic patients investigated with 131I-PVP.

Age Factors↗
PubMed1975

Crosslink in bone collagen in Paget's disease.

The crosslink in bone collagen was analysed in specimens of bone obtained at necropsy from cases of Paget's disease and compared with normal bone collagen of the same age. The specimens were stored at -20 degrees C before analysis. The predominant crosslink in a normal bone collagen was hydroxylysinohydroxynorleucine (di OH-LNL) (F1), which was designated syndesine in the past; another fraction, hydroxylysinorleucine (HLNL) (F2), musch less prominent than di OH-LNL, was also noted in a normal bone collagen. Both fractions were reduced in bone tissue of advancing age. The peak corresponding to HLNL was considerably increased in Paget's disease. This abnormality was constantly seen in specimens of bone from cases of Paget's disease, but the significance of the finging could not be assessed from the present investigation. Calcitonin has been shown to produce complete remission in Paget's disease and the crosslink pattern was found to be normal in specimens examined froma calcitonin-treated patient. This shows that calcitonin has some effect on the metabolism of collagen and a normal crosslink in such a situation lends support to this idea.

Adolescent↗