Racial patterns in the effects of tobacco use on fetal growth

Elevated Vascular Sympathetic Neurotransmission and Remodelling Is a Common Feature in a Rat Model of Foetal Programming of Hypertension and SHR

Hypertension is of unknown aetiology, with sympathetic nervous system hyperactivation being one of the possible contributors. Hypertension may have a developmental origin, owing to the exposure to adverse factors during the intrauterine period. Our hypothesis is that sympathetic hyperinnervation may be implicated in hypertension of developmental origins, being this is a common feature with essential hypertension. Two-animal models were used: spontaneously hypertensive rats (SHR-model of essential hypertension) and offspring from dams exposed to undernutrition (MUN-model of developmental hypertension), with their respective controls. In adult males, we assessed systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), sympathetic nerve function (3H-tritium release), sympathetic innervation (immunohistochemistry) and vascular remodelling (histology). MUN showed higher SBP/DBP, but not HR, while SHR exhibited higher SBP/DBP/HR. Regarding the mesenteric arteries, MUN and SHR showed reduced lumen, increased media and adventitial thickness and increased wall/lumen and connective tissue compared to respective controls. Regarding sympathetic nerve activation, MUN and SHR showed higher tritium release compared to controls. Total tritium tissue/tyrosine hydroxylase detection was higher in SHR and MUN adventitia arteries compared to respective controls. In conclusion, sympathetic hyperinnervation may be one of the contributors to vascular remodelling and hypertension in rats exposed to undernutrition during intrauterine life, which is a common feature with spontaneous hypertension.

Insights into sympathetic nervous system and GPCR interplay in fetal programming of hypertension: a bridge for new pharmacological strategies

Cardiovascular diseases (CVDs) are the most common cause of death from noncommunicable diseases worldwide. In addition to the classical CVD risk factors related to lifestyle and/or genetic background, exposure to an adverse intrauterine environment compromises fetal development leading to low birth weight and increasing offspring susceptibility to develop CVDs later in life, particularly hypertension - a process known as fetal programming of hypertension (FPH). In FPH animal models, permanent alterations have been detected in gene expression, in the structure and function of heart and blood vessels, compromising cardiovascular physiology and favoring hypertension development. This review focuses on the role of the sympathetic nervous system and its interplay with G-protein-coupled receptors, emphasizing strategies that envisage the prevention and/or treatment of FPH through interventions in early life.

Fetal sex and race modify the predictors of fetal growth

The objective of this study is unknown if fetal sex and race modify the impact of maternal pre-pregnancy body mass index (BMI), and smoking on fetal growth. The authors studied markers of fetal growth in singleton offspring of 8,801 primiparous, normotensive women, enrolled in the Collaborative Perinatal Project. The authors tested for departures from additivity between sex/race and each predictor. The head-to-chest circumference ratio (HCC) decreased more, while birthweight and ponderal index (PI) increased more for each 1 kg/m(2) increase in pre-pregnancy BMI among term females versus males (P = 0.07, P < 0.01 and P = 0.08, interaction respectively). For term offspring of White compared with Black women, smoking independent of "dose" was associated with larger reductions in growth (165 g vs. 68 g reduction in birthweight, P < 0.01, interaction), greater reduction in fetal placental ratio (P < 0.01, interaction), PI (P < 0.01, interaction), and greater increase in HCC (P = 0.02), respectively. The association of BMI and smoking with fetal size appeared to be reversed in term versus preterm infants. Our study provides evidence that the associations of pre-pregnancy BMI and smoking are not constant across sex and race. This finding may be relevant to sex and race differences in neonatal and long term health outcomes.

Exposure to environmental tobacco smoke and absence from work in women in Nis, Serbia

Exposure to environmental tobacco smoke leads to very serious health effects, especially on the respiratory system. The objective of this paper was to estimate the influence of passive smoking on absence from work because of respiratory problems in women. The study sample consisted of 497 women aged 40-56 who live in an area with identical outdoor air pollution. Environmental tobacco smoke exposure was recorded in 346 women. Data about respiratory symptoms in women were entered into a structured questionnaire. Statistics tests showed no significant difference of living conditions, keeping pets, hereditary predisposition among women. The occurrence of congested nose (OR = 3.47; 95% Cl = 1.38-9.01), nasal secretion (OR = 3.48; 95% Cl = 1.38-9.02) and sinusitis (OR = 2.88; 95% Cl = 1.22-6.89) was significantly higher in women who were exposed to environmental tobacco smoke. Primary health care need for respiratory symptoms due to the effect of passive smoking is higher in the exposed women. Passive smoking can be a risk factor for the appearance of respiratory symptoms and illness in women that causes absence from work.

Residential environmental tobacco smoke exposure during pregnancy and low birth weight of neonates: case control study in a public hospital in Lucknow, India

OBJECTIVE

To determine whether residential environmental tobacco smoke (ETS) exposure during pregnancy is associated with low birth weight (LBW) neonates and establish a dose response relationship.

DESIGN

Case control study.

SETTING

Tertiary care hospital.

METHODOLOGY

Mothers giving birth to LBW neonate (<2.5 kg) were cases and those whose neonates weighed =2.5 kg at birth were controls. Excluded were women smokers and tobacco chewers, high parity (>3), multiple pregnancy and still births. Included were 100 cases and 200 controls, aged 20 to 30 years. Information was collected on ETS exposure and other risk factors of LBW within 24 hours of delivery. Clinical information like maternal haemoglobin levels, birth weight and gestational age of the neonate was extracted from hospital records.

RESULTS

On univariate analysis, preterm pregnancy, low socioeconomic status, previous LBW neonate, no utilization of antenatal care (ANC), severe anemia and ETS exposure were statistically significantly associated with LBW neonate and controlling for these in logistic regression analysis, adjusted Odds ratio for ETS exposure association with LBW neonate was 3.16 (95% CI=1.88-5.28). A dose response relationship was also found which was statistically significant (10-20 cigarettes smoked/day: OR = 4.06, 95% CI=1.78-9.26 and >20 cigarettes smoked/day, OR = 17.62, 95% CI= 3.76-82.43).

CONCLUSION

Exposure to ETS during pregnancy is associated with LBW of neonates. Hence, there is an urgent need to increase awareness about health hazards of ETS during pregnancy and bring about behavioural changes accordingly as a one of the strategies to reduce LBW deliveries in India.

The incidence of prenatal alcohol exposure in Montevideo Uruguay as determined by meconium analysis

Prenatal alcohol exposure can lead to a wide range of deficits known as fetal alcohol spectrum disorder. Epidemiologic studies regarding alcohol consumption in pregnancy have concentrated on North America, but recent reports have suggested that consumption is significant in many parts of the world. In Uruguay, alcohol consumption has changed into more risky and dangerous patterns and thus has a theoretical risk of having a high rate of prenatal alcohol exposure. This study characterizes the incidence of prenatal alcohol exposure in Montevideo, Uruguay, using a novel biomarker, fatty acid ethyl esters, in meconium as well as a survey to mothers. Nine hundred five meconium samples were collected from Hospital Pereira Rossell and Hospital de Clínicas in Montevideo, Uruguay. A maternal questionnaire was also completed. Meconium was analyzed for fatty acid ethyl esters using liquid-liquid and solid phase extraction with gas chromatography-flame ionization detection. Meconium was also analyzed for other drugs of abuse using enzyme-linked immunosorbent assay. Forty-four percent of meconium samples were above the positive cutoff for fatty acid ethyl esters and represent those newborns with risky prenatal exposure during the final two trimesters of pregnancy. Infants with prenatal alcohol exposure were more likely to have prenatal exposure to tobacco (odds ratio, 1.56; 95% confidence interval, 1.11-2.20) or any illicit drug (odds ratio, 2.29; 95% confidence interval, 0.98-5.31). Ethyl linoleate was a significant predictor of infant birth weight along with prenatal tobacco exposure, maternal body mass index, and infant sex. This study highlights a 44% incidence of prenatal alcohol exposure.

The impact of maternal smoking on fast auditory brainstem responses

Deficits in auditory processing have been posited as one of the underlying neurodevelopmental consequences of maternal smoking during pregnancy that leads to later language and reading deficits. Fast auditory brainstem responses were used to assess differences in the sensory processing of auditory stimuli among infants with varying degrees of prenatal cigarette exposure. Maternal report of consumption of cigarettes and blood samples were collected in the hospital to assess exposure levels and participants were then seen at 6-months. To participate in the study, all infants had to pass the newborn hearing exam or a clinically administered ABR and have no known health problems. After controlling for participant age, maternal smoking during pregnancy was negatively related to latency of auditory brainstem responses. Of several potential covariates, only perinatal complications and maternal alcohol use were also related to latency of the ABR responses and maternal smoking level accounted for significant unique variance after controlling for these factors. These results suggest that the relationship between maternal smoking may lead to disruption in the sensory encoding of auditory stimuli.

Maternal smoking, preeclampsia, and infant health outcomes in New York City, 1995-2003

A number of previous studies have reported an inverse association between maternal smoking and preeclampsia. Additionally, some have suggested that smokers who develop preeclampsia have worse maternal and fetal outcomes than nonsmokers who develop preeclampsia. The authors examined the relation of smoking to preeclampsia among 674,250 singleton pregnancies in New York City between 1995 and 2003. Although smoking was associated with a reduced risk of preeclampsia overall (adjusted odds ratio = 0.88, 95% confidence interval: 0.82, 0.94), no association was found for preeclampsia superimposed on chronic hypertension (adjusted odds ratio = 1.04, 95% confidence interval: 0.90, 1.21). Furthermore, the apparent protection conferred by maternal smoking was restricted to women aged < or =30 years. Contrary to previous reports, the authors found evidence of a negative interaction between smoking and preeclampsia with respect to preterm delivery and birth weight; smokers who developed preeclampsia had a lower risk of preterm delivery, and a lower adjusted mean difference in birth weight, than would have been expected based on the independent effects of smoking and preeclampsia. These data suggest that smoking is only protective against preeclampsia without pre gestational hypertension, and even then principally among younger women. Additionally, smokers who develop these disorders have no increased risk of adverse birth outcomes relative to nonsmokers who develop the same conditions.

Combining Internal and External Validation Data to Correct for Exposure Misclassification

Internal validation data offer a well-recognized means to help correct for exposure misclassification or measurement error. When available, external validation data offer the advantage of cost-effectiveness. However, external data are a generally inefficient source of information about misclassification parameters. Furthermore, external data are not necessarily "transportable", for example, if there are differences in the design or target populations of the main and validation studies. Recent work has suggested weighted estimators to simultaneously take advantage of internal and external validation data. We explore efficiency and transportability in the fundamental case of estimating the odds ratio for binary exposure in a case-control setting. Our results support the use of closed-form weighted log odds ratio estimators in place of computationally demanding maximum likelihood estimators under both types of validation study designs (using internal data only, and combining internal and external data). We also provide and assess a formal test of the transportability assumption, and introduce a new log odds ratio estimator that is inherently robust to violation of that assumption. A case-control study of the association between maternal antibiotic use and sudden infant death syndrome provides a real-data example.

Maternal Alcohol Abuse and Neonatal Infection

BACKGROUND

Since chronic alcohol use suppresses the adult immune system, we tested the hypothesis that maternal alcohol ingestion increases the risk of infection in term newborns.

METHODS

Analysis of a large case-control study of birth weight for gestational age was performed focusing on maternal alcohol ingestion and the development of infection in term newborns > or =36 weeks gestation. After delivery, mothers were asked about alcohol and tobacco use in the 3 months prior to conception, the 1st, 2nd, and 3rd trimester of pregnancy.

RESULTS

Eight hundred and seventy-two singleton newborns (872) > or = 36 weeks gestation were identified for analysis. A total of 51 (5.8%) had newborn infections. Gestational age, sex, and small for gestational age (SGA) were similar in the newborns with and without infection (p = NS). Infants whose mothers reported alcohol use, excessive drinking or smoking in pregnancy were more likely to have a newborn diagnosed with an infection than were mothers who reported abstaining from alcohol or cigarettes (p < 0.05). When controlling for race and smoking, SGA infants whose mothers used any alcohol had a 2.5-fold increase risk of infection, while excessive alcohol use increased the risk 3-4-fold. In a multivariable logistic regression analysis controlling for low maternal income, smoking, and SGA, excessive alcohol use during the 2 trimester increased the risk of newborn infection (OR 3.7 [1.1,12.8], p < 0.05).

CONCLUSIONS

Excessive maternal alcohol use is associated with an increased risk of newborn infection in this patient sample. Increased awareness and further clinical investigations are warranted to address the detrimental effects of fetal alcohol exposure on the developing immune system.

Intrauterine growth retardation in full-term newborn infants with birth weights greater than 2,500 g

Intrauterine growth retardation (IUGR) is an overlooked problem in full-term infants with birth weights greater than 2,500 g. Birth weight less than the 10th percentile underestimates the presence of IUGR. The purpose of this study was to determine the prevalence of IUGR in full-term infants and to identify sociodemographic and maternal characteristics associated with IUGR. The Ohio Department of Health Vital Statistics database was used to obtain data related to sociodemographic and maternal characteristics. The fetal growth ratio (FGR) was used to determine the presence of IUGR. The sample consisted of 1,569 infants with normal ratios and 1,364 infants classified as IUGR. Infants with IUGR were more often male and African American or Asian American. Maternal characteristics associated with IUGR included history of smoking during pregnancy, lower pre-pregnancy weight, lower weight gain during pregnancy, and inadequate prenatal care. IUGR is present in a significant number of full-term infants with birth weights greater than 2,500 g. The long-term effects of IUGR in these infants remain to be determined.

Prenatal smoke exposure alters growth in limb proportions and head shape in the midgestation human fetus

The objective of this study was to examine the effects of smoke exposure on the growth patterns of the head, limbs, and torso of the midgestation human fetus. Four hundred maternal/fetal pairs contributed to this analysis: 366 individuals were assessed cross-sectionally (87 smokers and 279 nonsmokers) at approximately 20 and 32 weeks, and 34 individuals were followed longitudinally at 23, 27, and 32 weeks (10 smokers, 24 nonsmokers). Ten body parameters were measured by fetal ultrasound. In both samples, controlling for day of measurement, smoke exposure was significantly associated with early growth acceleration in head and abdominal diameters at 20-27 weeks (P < 0.05). This was followed by altered head shape (a significantly smaller biparietal to occipital frontal diameter ratio at 32 weeks, P < 0.01), and a proximal/distal growth gradient as proportionately long arms (P < 0.05 at 27 and 32 weeks) and short legs were apparent by 32 weeks, with a significant reduction in the tibia/femur ratio (P = 0.04). These fetal body growth patterns, expressed in terms of size and proportionality, are consistent with the presence of chronic hypoxia associated with maternal smoking. The growth pattern differences identify that prenatal smoking is not merely an insult resulting in consistent size and growth rate reduction across developmental ages. Instead, smoke exposure alters the growth rate of individual body segments at variable developmental stages as the fetus experiences selective growth restriction and augmentation. We hypothesize that the growth patterns observed here reflect the unique pattern of fetal blood flow favoring upper body oxygen distribution and extraction, together with genetically based adaptive strategies that permit the fetus to adjust the timing and magnitude of its growth to local environmental resources. It is possible that dolichocephaly is a previously unappreciated marker of fetal hypoxia. Reduced tibial growth may be a good marker for shortfall and a useful proxy for the adequacy of circulating resources more generally.

The impact of smoking and other substance use by urban women on the birthweight of their infants

The impact of maternal smoking and other substance use during pregnancy on infant birthweight is demonstrated in a sample of 766 urban women, using data collected in the Washington, D.C. Metropolitan Area Drug Study (DC*MADS). Women residing and giving birth in the District of Columbia were interviewed in 1992. A multivariable linear regression model was used to quantify the association between birthweight and the mother's use of cigarettes, alcohol, or illicit drugs during pregnancy, while controlling for possible confounding variables. The analysis focused on factors, including prenatal care and substance use during pregnancy that may contribute to low birthweight infants born to this sample of urban, predominantly black women. A woman's use of cigarettes, marijuana, and heroin during pregnancy was related to infant birthweight, but her use of alcohol and cocaine during pregnancy was not significantly related. Smoking during pregnancy was a strong predictor for low birthweight, suggesting that targeting more smoking cessation programs for pregnant women, particularly those who may also be illicit drug users, could help reduce adverse health consequences for low birthweight infants.

Smoking and pregnancy outcome among African-American and white women in central North Carolina

Despite extensive research on tobacco smoking during pregnancy, few studies address risks among African-American and white women, groups that differ in brand preference and smoking habits. The Pregnancy, Infection, and Nutrition Study is a prospective cohort study that included 2,418 women with detailed information on smoking during pregnancy, including brand, number of cigarettes per day, and changes during pregnancy. We analyzed risk of preterm birth (<37 and <34 weeks' gestation) and small-for-gestational-age deliveries in relation to tobacco use. Pregnant African-American smokers differed markedly from whites in brand preference (95% vs 26% smoked menthol cigarettes) and number of cigarettes per day (1% of African-Americans and 12% of whites smoked 20+ cigarettes per day). Smoking was not related to risk of preterm birth overall, but cotinine measured at the time of delivery was (adjusted odds ratio = 2.2, 95% confidence interval = 1.1-4.5). A clear association and dose-response gradient was present for risk of fetal growth restriction (risk ratio for 20+ cigarettes/day = 2.4, 95% confidence interval = 1.4-4.0). Associations of tobacco use with preterm premature rupture of amniotic membrane resulting in preterm birth were notably stronger than the associations with other types of preterm birth.