Urinary cotinine concentration confirms the reduced risk of preeclampsia with tobacco exposure

Modulation of preeclampsia by the cholinergic anti-inflammatory pathway: Therapeutic perspectives

The cholinergic anti-inflammatory pathway (CAP) is vital for the orchestration of the immune and inflammatory responses under normal and challenged conditions. Over the past two decades, peripheral and central circuits of CAP have been shown to be critically involved in dampening the inflammatory reaction in a wide array of inflammatory disorders. Additionally, emerging evidence supports a key role for CAP in the regulation of the female reproductive system during gestation as well as in the advent of serious pregnancy-related inflammatory insults such as preeclampsia (PE). Within this framework, the modulatory action of CAP encompasses the perinatal maternal and fetal adverse consequences that surface due to antenatal PE programming. Albeit, a considerable gap still exists in our knowledge of the precise cellular and molecular underpinnings of PE/CAP interaction, which hampered global efforts in safeguarding effective preventive or therapeutic measures against PE complications. Here, we summarize reports in the literature regarding the roles of peripheral and reflex cholinergic neuroinflammatory pathways of nicotinic acetylcholine receptors (nAChRs) in reprogramming PE complications in mothers and their progenies. The possible contributions of α7-nAChRs, cholinesterases, immune cells, adhesion molecules, angiogenesis, and endothelial dysfunction to the interaction have also been reviewed.

Nicotine Alleviates Cortical Neuronal Injury by Suppressing Neuroinflammation and Upregulating Neuronal PI3K-AKT Signaling in an Eclampsia-Like Seizure Model

Our previous studies showed that treatment with alpha7 nicotinic acetylcholine receptor (α7nAChR) agonist nicotine could alleviate systemic inflammation and reduce neuronal loss in the hippocampus and seizure severity in eclampsia. In this study, we further investigated whether there is also neuronal damage in the cortex after eclamptic seizure, elucidated the potential mechanisms underlying the neuroprotective roles of nicotine in eclampsia. Retrospective analysis of MRI data of severe preeclampsia (SPE) patients was conducted. A preeclampsia model was established by lipopolysaccharide injection (PE group), and pentylenetetrazol was used to induce eclamptic seizure (E group). α7nAChR agonist nicotine and its antagonist (α-BGT) and PI3K inhibitor wortmannin were used for drug administration. Neuronal damage was detected by Nissl staining, and changes in neuroinflammation, neuronal apoptosis, α7nAChR expression, and PI3K-AKT signaling on cortical neurons were detected by immunohistochemistry and western blotting. MRI images showed that most abnormal signals from the brain of SPE patients were located in the cortex. The neuron survival ratio was lower in the cortex than in the hippocampus within the E group; such ratios in the cortex were significantly lower in the E and PE groups compared with those of the control group. Nicotine markedly decreased the production of inflammatory cytokines and microglial activation in the cortex of the E group. Moreover, nicotine increased p-AKT levels and decreased cleaved caspase-3 levels in cortical neurons. Treatment with α-BGT reversed effects of nicotine. Wortmannin also blocked the anti-neuronal apoptosis action of nicotine. Our results suggest that nicotine protects against neuronal injury in the cortex following eclampsia possibly by inhibiting neuroinflammation and activating neuronal PI3K-AKT pathway.

Left truncation bias as a potential explanation for the protective effect of smoking on preeclampsia

Supplemental Digital Content is available in the text.

Background:

We carried out a study to examine whether left truncation bias could explain the negative association between smoking and preeclampsia.

Methods:

Monte Carlo and other simulation models were used to determine the effect of differential rates of early pregnancy loss among smokers on the relation between smoking and preeclampsia at ≥20 weeks’ gestation. Assumptions included no association between smoking and the abnormal placentation that characterizes preeclampsia, and higher rates of early pregnancy loss among smokers, pregnancies with abnormal placentation, and smokers with abnormal placentation.

Results:

Monte Carlo simulation yielded a rate ratio for preeclampsia, given smoking of 0.85 (95% confidence interval = 0.73, 0.98). The protective effect of smoking was also evident in simulations that did not require assumptions about early pregnancy loss rates.

Conclusion:

Left truncation bias due to differential rates of early pregnancy loss among smokers is a plausible explanation for the inverse association between maternal smoking and preeclampsia.

Plasma cotinine indicates an increased risk of preeclampsia in previous and passive smokers

OBJECTIVE

Self-reported tobacco smoking in pregnancy has been consistently associated with a decreased risk of developing preeclampsia, but the evidence has been limited and inconsistent for previous and passive smokers. Misclassifications and inaccuracies of self-reported tobacco exposure may disguise the true relationship. This study aimed to assess the association of gestational hypertension and preeclampsia with maternal smoking status as ascertained by plasma cotinine.

STUDY DESIGN

This was a prospective study of 605 pregnant women without chronic hypertension. Maternal smoking status at 24-26 weeks' gestation was defined by plasma cotinine: >3.0 ng/mL "current smokers," 0.20-3.00 ng/mL "previous and passive smokers," and <0.20 ng/mL "nonsmokers."

RESULTS

Compared to nonsmokers, the risk of developing preeclampsia did not change significantly for current smokers, but increased significantly (adjusted odds ratio, 6.06; 95% confidence interval, 2.32-15.85; P < .001) for previous and passive smokers. There were no significant differences in the risk of developing gestational hypertension only.

CONCLUSION

Previous and passive smoking may increase the risk of preeclampsia. Avoidance of exposure to environmental tobacco smoke in pregnancy may decrease the risk of preeclampsia.

Exploratory quantile regression with many covariates: an application to adverse birth outcomes

Covariates may affect continuous responses differently at various points of the response distribution. For example, some exposure might have minimal impact on conditional means, whereas it might lower conditional 10th percentiles sharply. Such differential effects can be important to detect. In studies of the determinants of birth weight, for instance, it is critical to identify exposures like the one above, since low birth weight is a risk factor for later health problems. Effects of covariates on the tails of distributions can be obscured by models (such as linear regression) that estimate conditional means; however, effects on tails can be detected by quantile regression. We present 2 approaches for exploring high-dimensional predictor spaces to identify important predictors for quantile regression. These are based on the lasso and elastic net penalties. We apply the approaches to a prospective cohort study of adverse birth outcomes that includes a wide array of demographic, medical, psychosocial, and environmental variables. Although tobacco exposure is known to be associated with lower birth weights, the analysis suggests an interesting interaction effect not previously reported: tobacco exposure depresses the 20th and 30th percentiles of birth weight more strongly when mothers have high levels of lead in their blood compared with those who have low blood lead levels.

Nicotine and cotinine affect the release of vasoactive factors by trophoblast cells and human umbilical vein endothelial cells

OBJECTIVE

To examine nicotine (N) and cotinine (C) effects on trophoblast cells (TCs) and human umbilical vein endothelial cells (HUVEC) secretion of soluble fms-like tyrosine kinase (sFlt-1), soluble endoglin (sENG), placental growth factor (PlGF), transforming growth factor-beta (TGF-beta) and vascular endothelial growth factor (VEGF).

STUDY DESIGN

Human placentas and umbilical cords were collected from uncomplicated pregnancies at term from a total of 24 non-smoking women with a history of normal blood pressure. TCs and HUVEC were cultured for 24 h with C or N (from 10(-12) to 10(-7) M).

MAIN OUTCOME MEASURES

sFlt-1, sENG, PlGF, TGF-beta and VEGF release and messenger RNA (mRNA) expression were evaluated by ELISA and real-time polymerase chain reaction (PCR), respectively.

RESULTS

N and C reduced sFlt-1, sENG and PlGF release by TCs and TGF-beta release by HUVEC. Conversely, N and C increased PlGF secretion, while N alone increased sFlt-1 release by HUVEC. N and C were able to modulate VEGF mRNA expression in HUVEC.

CONCLUSIONS

Our results suggest that N and C affect the balance of some important vasoactive factors released by TCs and HUVEC. This might be one of the possible mechanism through which smoke reduces the risk of hypertensive disorders during pregnancy as well as contributes to the well known detrimental effects of smoking on fetal development.

The risk of adverse pregnancy outcomes is increased in preeclamptic women who smoke compared with nonpreeclamptic women who do not smoke

OBJECTIVE

Maternal smoking and preeclampsia independently increase the risk of adverse pregnancy outcomes; however, smoking decreases the risk of preeclampsia. We sought to estimate the risk of adverse pregnancy outcomes among preeclamptic women who smoke and hypothesized that this risk would be increased, compared with nonpreeclamptic women who smoke or preeclamptic women who do not smoke.

STUDY DESIGN

With the use of the Niday Perinatal Database and multiple logistic regressions, we estimated the risk of adverse pregnancy outcomes in nonpreeclamptic women who smoke, preeclamptic women who do not smoke, and preeclamptic women who smoke in relation to nonpreeclamptic women who do not smoke.

RESULTS

The incidence of adverse pregnancy outcomes was more than twice as high among preeclamptic women who smoke as among nonpreeclamptic women who do not smoke. The following data were observed: small-for-gestational-age infant (odds ratio [OR], 3.40; 95% CI, 2.27-4.89), preterm birth (OR, 5.77; 95% CI, 4.50-7.35), very preterm birth (OR, 5.44; 95% CI, 3.51-8.11), abruption (OR, 6.16; 95% CI, 3.05-11.01), Apgar <4 at 5 minutes (OR, 3.11; 95% CI, 1.48-5.72), and stillbirth (OR, 3.39; 95% CI, 1.33-6.99).

CONCLUSION

Smoking decreases the risk of preeclampsia, but smokers with preeclampsia have an increased risk for adverse pregnancy outcomes.

The origin of pre-eclampsia: from decidual "hyperoxia" to late hypoxia

Normal gestation implants on a relatively hypoxic deciduas so that trophoblast deeply invades endometrium and angiogenesis seeks for oxygen supply. If implantation occurs before those hypoxic conditions occur, trophoblast invasion is defective, due to the relatively high oxygen tension in the decidual environment, laying the foundations for subsequent pre-eclampsia.

Association of cotinine levels and preeclampsia among African-American women

INTRODUCTION

Although prior studies have shown that smoking reduces preeclampsia risk, the relationship between nicotine level and preeclampsia risk is not known. Our objective was to study the effects of smoking on the incidence of preeclampsia in African-American women using cotinine, a quantitative marker of nicotine.

METHODS

We performed a secondary analysis of data collected prospectively in Project District of Columbia Healthy Outcomes of Pregnancy Education. Our study included 724 African-American women. Self-reported smoking, cotinine levels, and pregnancy outcomes were examined.

RESULTS

Some 18% of participants were smokers. Women with salivary cotinine levels greater than 200 ng/ml had infants with lower birth weights and a higher incidence of small-for-gestational-age infants than women with cotinine levels of 200 ng/ml or less. Exact logistic regression analysis revealed that women with salivary cotinine levels greater than 200 ng/ml had a significantly lower incidence of preeclampsia, compared with women with cotinine levels of 200 ng/ml or less, in unadjusted analysis (odds ratio [OR] = 0.16, 95% CI = 0-0.90). After controlling for age, parity, and medical comorbidities, the trend was observed, but the effect was no longer significant (adjusted odds ratio [AOR] = 0.19, 95% CI = 0-1.11). We found no significant differences in preeclampsia rates using lower cutoffs of cotinine exposure. We did not observe a decrease in preeclampsia incidence at low or moderate cotinine levels.

DISCUSSION

Women with the highest cotinine levels may have a decreased risk for preeclampsia, although this effect was not significant after controlling for other risk factors.

Placental angiogenesis markers sFlt-1 and PlGF: response to cigarette smoke

OBJECTIVE

Excess soluble vascular endothelial growth factor receptor, fms-like tyrosine kinase-1 (sFlt-1), and reduced placental growth factor (PlGF) mediate the genesis of preeclampsia. Cigarette smoking reduces the risk of preeclampsia. We hypothesized that placental secretion of sFlt-1 and PlGF was affected by exposure to cigarette smoke extract.

STUDY DESIGN

Term placental villous explants were cultured with cigarette smoke extract. Media were analyzed for sFlt-1 and PlGF. Apoptosis was measured by TUNEL staining. Results are reported as sFlt-1 or PlGF picogram/milliliter/milligram wet weight of explant.

RESULTS

Exposure to cigarette smoke extract reduced secretion of sFlt-1 in a dose-dependent manner. There was no difference in apoptosis. In contrast with sFlt-1, PlGF did not decline when incubated with cigarette smoke extract.

CONCLUSION

Exposure of placental villous explants to cigarette smoke extract results in a proangiogenic state with reduced sFlt-1 and relative abundance of PlGF. This is the reverse of changes that are seen in preeclampsia and may explain the reduction of preeclampsia in smokers.

Negative regulation of soluble Flt-1 and soluble endoglin release by heme oxygenase-1

BACKGROUND

Preeclampsia is characterized clinically by hypertension and proteinuria. Soluble Flt-1 (sFlt-1; also known as soluble vascular endothelial growth factor receptor-1 [VEGFR-1]) and soluble endoglin (sEng) are elevated in preeclampsia, and their administration to pregnant rats elicits preeclampsia-like symptoms. Heme oxygenase-1 (HO-1) and its metabolite carbon monoxide (CO) exert protective effects against oxidative stimuli. Thus, we hypothesized that HO-1 upregulation may offer protection against preeclampsia by inhibiting sFlt-1 and sEng release.

METHODS AND RESULTS

Preeclamptic villous explants secreted high levels of sFlt-1 and sEng. Adenoviral overexpression of HO-1 in endothelial cells inhibited VEGF-mediated sFlt-1 release and interferon-gamma- and tumor necrosis factor-alpha-induced sEng release, whereas HO-1 inhibition potentiated sFlt-1 and sEng production from endothelial cells and placental villous explants. Consistent with these findings, mice lacking HO-1 produced higher levels of sFlt-1 and sEng compared with wild-type mice. Using selective ligands (VEGF-E and placental growth factor) and a receptor-specific inhibitor (SU-1498), we demonstrated that VEGF-induced sFlt-1 release was VEGFR-2 dependent. Furthermore, CO-releasing molecule-2 (CORM-2) or CO decreased sFlt-1 release and inhibited VEGFR-2 phosphorylation. Treatment of endothelial cells with statins upregulated HO-1 and inhibited the release of sFlt-1, whereas vitamins C and E had no effect.

CONCLUSIONS

The present study demonstrates that the HO-1/CO pathway inhibits sFlt-1 and sEng release, providing compelling evidence for a protective role of HO-1 in pregnancy, and identifies HO-1 as a novel target for the treatment of preeclampsia.

Maternal Smoking and Testicular Germ Cell Tumors

Testicular germ cell tumors (TGCT) are the most common cancer among men ages 15 to 35 years in the United States. The well-established TGCT risk factors cryptorchism, prior diagnosis of TGCT, and family history of testicular cancer indicate that exposures in early life and/or in the familial setting may be critical to determining risk. Previous reports of familial clustering of lung cancer in mothers and testicular cancers in sons suggest that passive smoking in childhood may be such an exposure. To clarify the relationship of passive smoking exposure to TGCT risk, data from 754 cases and 928 controls enrolled in the Servicemen's Testicular Tumor Environmental and Endocrine Determinants study were analyzed. Data from 1,086 mothers of the cases and controls were also examined. Overall, there was no relationship between maternal [odds ratio (OR), 1.1; 95% confidence interval (95% CI), 0.9-1.3] or paternal smoking (OR, 1.0; 95% CI, 0.8-1.3) and TGCT risk. Although living with a non-parent smoker was marginally related to risk (OR, 1.4; 95% CI, 1.0-2.1), there was no relationship with number of smokers, amount smoked, or duration of smoking. Responses from both case-control participants and mothers also revealed no relationship between either maternal smoking while pregnant or while breast-feeding. Results did not differ by TGCT histology (seminoma, non-seminoma). These results do not support the hypothesis that passive smoking, either in utero or in childhood, is related to risk of TGCT. Other early life exposures, however, may explain the familial clustering of lung cancer in mothers and TGCT in sons.

Genetic polymorphisms of vascular endothelial growth factor in severe pre-eclampsia

Several lines of evidence support the hypothesis that vascular endothelial growth factor (VEGF) plays an important role in the pathogenesis of pre-eclampsia (PE). VEGF is a key component in the regulation of vascular remodelling and the survival of cytotrophoblasts in the placenta. In this case-control study, we aimed to test whether VEGF genetic polymorphisms are associated with the risk of severe PE. We enrolled 84 nulliparous pregnant women with severe PE (PE group). Their VEGF G(+405)C and VEGF C(-2578)A genotypes were determined by PCR-restriction fragment length polymorphism (PCR-RFLP) from venous blood samples and were compared with the corresponding VEGF genotypes of 96 nulliparous patients with uncomplicated pregnancies (control group). Carriers of the VEGF(+405)G allele occurred less frequently in PE than in the control group [P = 0.039; adjusted odds ratio (aOR) = 0.28, range: 0.08-0.93]. Hypertension and proteinuria were diagnosed earlier (by 1.6 weeks and 1.9 weeks, respectively) in PE patients with VEGF(-2578)A only after adjustment of this association for risk factors of PE. Our results suggest that carriers of VEGF(+405)G allele have a decreased susceptibility to PE and that the progression of PE may be modified by the presence of VEGF(-2578)A allele. Nevertheless, the clinical significance of these findings remains to be determined.

Cervical anti-inflammatory cytokine concentrations among first-trimester pregnant smokers

OBJECTIVE

Anti-inflammatory cytokines play a role in the lower genital tract immune defense. We examined the impact of cigarette smoking in pregnancy on the detection of the 3 most important anti-inflammatory cytokines (interleukin-4, -10, and -13) in the cervix.

STUDY DESIGN

One hundred fourteen gravid women from 4 to 16 weeks of gestation without bacterial vaginosis or sexually transmitted disease were queried regarding demographic factors and smoking. Concentrations of cytokines were determined with a multiplex assay for cervical swabs.

RESULTS

There was a positive linear relationship between the number of cigarettes that were smoked per day and cervical concentrations of interleukin-4, -10, and -13 (P < .001 for each). Median concentrations of interleukin-4 and -10 were greater among women who smoked > or = 20 cigarettes per day than among non-smokers or less heavy smokers (P < .05 for both). There was no difference in concentrations of proinflammatory cytokines between smokers and non-smokers.

CONCLUSION

Cigarette smoking in pregnancy is associated with an increase of cervical anti-inflammatory cytokines without a commensurate increase of proinflammatory cytokines. This may have important impact on the host response to infection.

Maternal cigarette smoking and the risk of pregnancy-induced hypertension and eclampsia

BACKGROUND

Although previous studies have found that maternal smoking decreases the risk of pregnancy-induced hypertension (PIH), the difference of this effect between primiparous and multiparous women has not been well studied and the results of the exposure-response relationships between maternal smoking and PIH are inconsistent. No previous study has specifically examined the relationship between maternal smoking and eclampsia.

METHODS

We analysed data from a population-based retrospective cohort study of 3 153 944 singleton pregnancies in the US. The data were derived from the national linked birth/infant mortality database for 1998. Multiple logistic regressions were used to describe the relationship between cigarette smoking and PIH and eclampsia.

RESULTS

The adjusted odds ratios (ORs) [95% confidence intervals (95% CIs)] for PIH were 0.80 (0.77-0.83) for primiparous women and 0.81 (0.78-0.83) for multiparous women among smokers compared with non-smokers. The corresponding adjusted ORs (95% CIs) for eclampsia were 0.74 (0.66-0.82) and 0.75 (0.68-0.83), respectively. For PIH, the adjusted OR (95% CI) for smokers vs non-smokers were 0.82 (0.79-0.86), 0.81 (0.78-0.83), 0.80 (0.77-0.83), and 0.88 (0.79-0.98), respectively, for 1-5, 6-10, 11-20, and >20 cigarettes per day (test for trend: P = 0.86). The corresponding figures for eclampsia were 0.85 (0.75-0.95), 0.74 (0.66-0.82), 0.68 (0.58-0.78), and 0.73 (0.49-1.04), respectively (test for trend: P = 0.02).

CONCLUSION

Maternal cigarette smoking decreases the risk of PIH and eclampsia, with a significant inverse exposure-response relationship apparent for eclampsia.

The Effect of Fetal Number on the Development of Hypertensive Conditions of Pregnancy

OBJECTIVE

To estimate the incidence and effect of pregnancy-related hypertensive conditions on multiple gestations.

METHODS

Women with 1-4 fetuses enrolled in an outpatient perinatal services program at 28 or more weeks of gestation were identified. Those without a prior diagnosis of hypertension at enrollment and who delivered at more than 28 weeks of gestation were included in the analysis. The incidence of all pregnancy-related hypertensive conditions, diagnosis of severe hypertensive conditions (hemolysis, elevated liver enzymes and low platelets syndrome; disseminated intravascular coagulation; eclampsia; low platelets; renal failure; and abruption), and interventional delivery related to hypertension were estimated, and compared according to fetal number.

RESULTS

Data were analyzed for 34,374 singleton, twin, triplet, and quadruplet gestations. The incidence of pregnancy-related hypertensive conditions increased with multifetal gestations as compared with singletons (12.7-19.6% for multifetal gestations compared with 6.5% for singletons, P < .001). The incidence of severe pregnancy-related hypertensive conditions was significantly increased in twin (1.6%) and triplet (3.1%) gestations as compared with singletons (0.5%, P < .001). Quadruplet pregnancies were not significantly higher than triplet gestations for these complications. The need for early delivery related to hypertension was greater with increasing fetal number through triplet gestations. By logistic regression, higher fetal number, nulliparity, and advanced maternal age were each independently associated with the development of pregnancy-related hypertensive conditions.

CONCLUSION

Mild and severe pregnancy-related hypertensive disease increases progressively with advancing fetal number from singleton to triplets but is not further increased in quadruplet pregnancies. Multifetal pregnancies should be observed closely for onset of gestational hypertensive disease.

LEVEL OF EVIDENCE

II-2.

Self-Reported and Serum Cotinine-Validated Smoking in Pregnant Women in Estonia

OBJECTIVES

Although widely used in epidemiological studies, self-report has been shown to underestimate the prevalence of smoking among pregnant women. Objectives of this study were to examine the discrepancy between self-reported and cotinine-validated smoking status, and the sociodemographic characteristics associated with the misclassification of real smoking status among pregnant women in Tallinn, the capital of Estonia.

METHODS

Serum cotinine assays were performed on a subsample (n = 1360) of the pregnant women, who had participated in a recent study of human papillomavirus type 16 (HPV-16) seroprevalence in Estonia. In the present study, serum concentrations > or = 15 ng/ml were used to distinguish current smokers from nonsmokers. The serum-validated smoking level was compared with the self-reported level in the records of the Estonian Medical Birth Registry. For the group of self-reported non-smokers, the differences between the cotinine-validated smokers and the cotinine-validated nonsmokers, with respect to their sociodemographic characteristics (age, ethnicity, educational level, employment status, marital status, parity), were estimated by logistic regression.

RESULTS

Of 1239 women who reported being nonsmokers, 259 (20.9%) had serum cotinine levels > or = 15 ng/ml, and can be regarded as current smokers. Among self-reported nonsmokers, nondisclosure of current smoking was significantly more frequent in non-Estonian, less educated, socially inactive, cohabiting and multiparous women.

CONCLUSIONS

Self-reported data on smoking in pregnant women underestimates the real smoking prevalence in Estonia. Maternal unwillingness to declare smoking during pregnancy needs to be taken into account in the practice of maternal and child health to better target prenatal smoking cessation interventions.

Maternal serum soluble fms-like tyrosine kinase 1 concentrations are not increased in early pregnancy and decrease more slowly postpartum in women who develop preeclampsia

OBJECTIVE

We measured maternal serum soluble fms-like tyrosine kinase 1 concentrations across pregnancy and immediately postpartum in women who developed preeclampsia and normal pregnant women.

STUDY DESIGN

This was a nested case control study of 113 normal pregnant women and 55 women with preeclampsia.

RESULTS

Serum soluble fms-like tyrosine kinase 1 concentrations increased similarly in early pregnancy in both groups. Mean serum soluble fms-like tyrosine kinase 1 concentrations were increased in women who developed preeclampsia, compared with normal pregnant women, and this increase was most pronounced in severe preeclampsia. However, many women with preeclampsia had soluble fms-like tyrosine kinase 1 concentrations similar to normal pregnant women. Lastly, soluble fms-like tyrosine kinase 1 decreased rapidly after delivery, but this decrease was significantly slower in women with severe preeclampsia.

CONCLUSION

Increased soluble fms-like tyrosine kinase 1 is not an early-pregnancy event among women who later develop preeclampsia. Increased soluble fms-like tyrosine kinase 1 is more likely to be present in women with severe preeclampsia, but it is not present in all women with preeclampsia. Soluble fms-like tyrosine kinase 1 concentrations decrease more slowly after delivery in women with preeclampsia, consistent with a decreased rate of excretion or continued production.

Smoking in pregnancy revisited: findings from a large population-based study

OBJECTIVE

The purpose of this study was to characterize the effect of smoking on the incidence of various pregnancy complications.

STUDY DESIGN

A population-based retrospective analysis with a perinatal database of 170,254 singleton pregnancies was performed. The rate of pregnancy complications was calculated in 4 strata of smokers: Nonsmokers, 1 to 5 cigarettes per day, 6 to 10 cigarettes per day, and >10 cigarettes per day. Logistic regression was used to calculate odds ratios as measures of an association of smoking with various pregnancy complications after correction for confounding factors.

RESULTS

The mean age of the study population was 29 +/- 4.8 years. The odds ratio for preeclampsia was 0.64 (95 % CI, 0.59-0.70), for intrauterine growth restriction was 2.4 (95% CI, 2.34-2.53), and for preterm delivery was 1.2 (95% CI, 1.13-1.28).

CONCLUSION

Smoking decreased the incidence of preeclampsia in a dose-effect manner and was shown to increase the rate of intrauterine growth restriction and preterm delivery.

Smoking during pregnancy is associated with alterations in markers of endothelial function

OBJECTIVE

Alterations in endothelial function may explain the reduced risk of preeclampsia that is associated with smoking. We hypothesized that markers of endothelial function increase over pregnancy but decrease with smoking.

STUDY DESIGN

Plasma samples were obtained throughout pregnancy from 63 primiparous women with normal pregnancies. The samples were assayed for cellular fibronectin, vascular cell adhesion molecule-1, and intracellular adhesion molecule-1. Smoking status was determined by urinary cotinine concentrations.

RESULTS

Mean cellular fibronectin concentrations were different by time (P<.001) and smoking status (P=.01); the lowest concentrations were found in smokers. In contrast, intracellular adhesion molecule-1 was different by smoking status (P=.046); the highest concentrations were found in smokers. Vascular cell adhesion molecule-1 was different over time (P<.001), but not by smoking status.

CONCLUSION

Smoking during pregnancy is associated with reduced cellular fibronectin and increased intracellular adhesion molecule-1. These differences may be the result of different aspects of endothelial function or the source of the marker. The explanation for reduced preeclampsia in smokers remains elusive.

Accuracy of self-reported cigarette smoking among pregnant women in the 1990s

In large, prospective studies of pregnancy conducted in the 1960s, women reported very accurately whether or not they smoked. However, in the 1990s, pregnant women who smoke are often pressured to reduce or quit smoking, and the incentive to misreport may be greater than in the past. To assess the accuracy of reported smoking, the authors compared self-reported smoking with cotinine in the serum and/or urine of 105 women who participated in the Calcium for Pre-eclampsia Prevention pilot study in 1992. Cotinine confirmed the report of 84.6% of women who reported smoking and 94.5% of women who denied smoking. These fractions are virtually identical to those obtained in a pregnancy cohort from the 1960s. The authors conclude that in the setting of two obstetrical research studies not specifically focused on smoking, the accuracy of self-reported cigarette smoking did not change substantially from the 1960s to the 1990s.