Smoking in moderate/severe preeclampsia worsens pregnancy outcome, but smoking cessation limits the damage

Why Female Smokers Have Poorer Long-Term Health Outcomes than Male Smokers: The Role of Cigarette Smoking During Pregnancy

Objectives: Women's health status is better than men but the opposite is true for female smokers who usually have poorer long-health outcomes than male smokers. The objectives of this study were to thoroughly reviewed and analyzed relevant literature and to propose a hypothesis that may explain this paradox phenomenon. Methods: We conducted a search of literature from three English databases (EMBASE, MEDLINE, and Google Scholar) from inception to 13 November 2023. A combination of key words and/or subject headings in English was applied, including relevant terms for cigarette smoking, sex/gender, pregnancy, and health indicators. We then performed analysis of the searched literature. Results: Based on this review/analysis of literature, we proposed a hypothesis that may explain this paradox phenomenon: female smokers have worse long-term health outcomes than male smokers because some of them smoke during pregnancy, and the adverse effects of cigarette smoking during pregnancy is much stronger than cigarette smoking during non-pregnancy periods. Conclusion: Approval of our pregnancy-amplification theory could provide additional evidence on the adverse effect on women's long-term health outcomes for cigarette smoking during pregnancy.

Reevaluating the protective effect of smoking on preeclampsia risk through the lens of bias

Preeclampsia is a hypertensive disorder that is usually diagnosed after 20 weeks' gestation. Despite the deleterious effect of smoking on cardiovascular disease, it has been frequently reported that smoking has a protective effect on preeclampsia risk and biological explanations have been proposed. However, in this manuscript, we present multiple sources of bias that could explain this association. First, key concepts in epidemiology are reviewed: confounder, collider, and mediator. Then, we describe how eligibility criteria, losses of women potentially at risk, misclassification, or performing incorrect adjustments can create bias. We provide examples to show that strategies to control for confounders may fail when they are applied to variables that are not confounders. Finally, we outline potential approaches to manage this controversial effect. We conclude that there is probably no single epidemiological explanation for this counterintuitive association.

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.

Presión arterial en embarazos normales de la Ciudad de México

OBJECTIVE

To determine the normal blood pressure (BP) in pregnancy, Mexico City.

METHODS

A cross-sectional observational study was carried out of BP on singleton normal pregnancies in Mexico City. Measurements followed a standardised methodology using automated electronic devices. Reference values of systolic (SBP), diastolic (DBP) and mean arterial pressure (MAP) were constructed. Maternal and gestation characteristics effects on BP were tested. The reference ranges of BP were adjusted for significant variables.

RESULTS

On 1,056 women of 33 years old mean age and 160.0 cm mean height, 1,915 measurements were made between 5 and 41 weeks of gestational age (GA) with 65.0 kg of mean weight. The median BP throughout pregnancy was 102.7/67.2 ± 9.3/7.4 SD mmHg, and 79.0 ± 7.4 SD mmHg the MAP. BP had a quadratic relationship with GA, being the lowest in 2nd trimester. SBP and DBP had a r = 0.71 linear correlation. Maternal weight had the most significant effect on SBP and MAP; height, on DBP. Maternal age, ethnic origin, parity, tobacco habit and family history had differential effects on BP. Gestation had no significant effect on SBP multivariate model.

CONCLUSIONS

BP resulted lower than conventional standard for pregnant women. Diagnostic criteria for hypertension in pregnancy must be revised; reference values can be adjusted by maternal and gestation characteristics.

Neonatal outcomes of extremely preterm infants exposed to maternal hypertension and cigarette smoking

OBJECTIVE

To study the outcomes of extremely preterm infants of hypertensive mothers who smoke.

STUDY DESIGN

This retrospective cohort study included infants born between 2003 and 2012 at <29 weeks' gestation and admitted to neonatal intensive care units participating in the Canadian Neonatal Network. Infants were divided into four mutually exclusive groups. Infants of hypertensive mothers who smoked; infants of hypertensive, non-smoking mothers; infants of normotensive mothers who smoked; and infants of normotensive, non-smoking mothers. Using infants of normotensive, non-smoking mothers as the reference group, neonatal outcomes were compared between the groups. Adjusted odds ratios (AORs) and 95% confidence intervals (CIs) were calculated using univariate and multivariate regression analysis.

RESULTS

Of the 12,307 eligible infants, 172 had hypertensive mothers who smoked, 1689 had hypertensive non-smoking mothers, 1535 had normotensive mothers who smoked, and 8911 had normotensive non-smoking mothers. Compared to infants of normotensive non-smoking mothers, infants of hypertensive mothers, regardless of smoking status, had higher odds of developing bronchopulmonary dysplasia (AORs of smokers 1.62; 95% CI 1.12-2.35 and of non-smokers 1.43; 95% CI 1.24-1.64). There was no difference in the odds of mortality and retinopathy of prematurity stage ≥3 between the groups. Infants of hypertensive, non-smoking mothers had decreased odds of intraventricular hemorrhage >grade 2 and higher odds of necrotizing enterocolitis. There was decreased odds of hypertension if the mother was a smoker (AOR 0.71; 95% CI 0.59-0.85).

CONCLUSION

Maternal hypertension is associated with increased rates of bronchopulmonary dysplasia, irrespective of smoking status.

Maternal and Paternal Height and the Risk of Preeclampsia

The etiology of preeclampsia is unknown. Tall women have been found to have lower incidence of preeclampsia. This points to a possible biological causal effect but may be because of socioeconomic confounding. We used paternal height as an unexposed control to examine confounding. The MoBa (Norwegian Mother and Child Cohort Study) was used to extract data on parental heights, maternal prepregnancy weight, other background factors, and pregnancy outcomes for 99 968 singleton births. Multiple logistic regression was used to estimate odds ratios for preeclampsia according to parental height. The adjusted odds ratio for preeclampsia was 0.74 (95% CI, 0.66-0.82) for women >172 cm as compared with women <164 cm. The adjusted odds ratio for preeclampsia for men >186 cm was 1.03 (95% CI, 0.93-1.15) compared with men <178 cm. The association between maternal height and preeclampsia is unlikely to be because of confounding by familial, socioeconomic factors or by fetal genes related to height. The observed association between maternal height and preeclampsia merits further investigation.

First-trimester smoking cessation in pregnancy did not increase the risk of preeclampsia/eclampsia: A Murmansk County Birth Registry study

Background

Although prior studies have shown that smoking reduces preeclampsia/eclampsia risk, the consequence of giving up this habit during pregnancy should be assessed. The aims of the current study were threefold: (i) describe maternal characteristics of women with preeclampsia/eclampsia; (ii) examine a possible association between the number of cigarettes smoked daily during pregnancy and the development of this affliction; and (iii) determine if first-trimester discontinuation of smoking during pregnancy influences the risk.

Methods

A registry-based study was conducted using data from the Murmansk County Birth Registry (MCBR). It included women without pre-existing hypertension, who delivered a singleton infant during 2006–2011 and had attended the first antenatal visit before 12 week of gestation. We adjusted for potential confounders using logistic regression.

Results

The prevalence of preeclampsia/eclampsia was 8.3% (95%CI: 8.0–8.6). Preeclampsia/eclampsia associated with maternal age, education, marital status, parity, excessive weight gain and body mass index at the first antenatal visit. There was a dose-response relationship between the number of smoked cigarettes per day during pregnancy and the risk of preeclampsia/eclampsia (adjusted OR_{1-5 cig/day} = 0.69 with 95%CI: 0.56–0.87; OR_{6-10 cig/day} = 0.65 with 95%CI: 0.51–0.82; and OR_{≥11 cig/day} = 0.49 with 95%CI: 0.30–0.81). There was no difference in this risk among women who smoked before and during pregnancy and those who did so before but not during pregnancy (adjusted OR = 1.10 with 95%CI: 0.91–1.32).

Conclusions

Preeclampsia/eclampsia was associated with maternal age, education, marital status, parity, excessive weight gain, and body mass index at the first antenatal visit. There was a negative dose-response relationship between the number of smoked cigarettes per day during pregnancy and the odds of preeclampsia/eclampsia. However, women who gave up smoking during the first trimester of gestation had the same risk of preeclampsia/eclampsia as those who smoked while pregnant. Consequently, antenatal clinic specialists are advised to take these various observations into account when counselling women on smoking cessation during pregnancy.

Interaction of p-benzoquinone with hemoglobin in smoker's blood causes alteration of structure and loss of oxygen binding capacity

Cigarette smoke (CS) is an important source of morbidity and early mortality worldwide. Besides causing various life-threatening diseases, CS is also known to cause hypoxia. Chronic hypoxia would induce early aging and premature death. Continuation of smoking during pregnancy is a known risk for the unborn child. Although carbon monoxide (CO) is considered to be a cause of hypoxia, the effect of other component(s) of CS on hypoxia is not known. Here we show by immunoblots and mass spectra analyses that in smoker's blood p-benzoquinone (p-BQ) derived from CS forms covalent adducts with cysteine 93 residues in both the β chains of hemoglobin (Hb) producing Hb-p-BQ adducts. UV-vis spectra and CD spectra analyses show that upon complexation with p-BQ the structure of Hb is altered. Compared to nonsmoker's Hb, the content of α-helix decreased significantly in smoker's Hb (p = 0.0224). p-BQ also induces aggregation of smoker's Hb as demonstrated by SDS-PAGE, dynamic light scattering and atomic force microscopy. Alteration of Hb structure in smoker's blood is accompanied by reduced oxygen binding capacity. Our results provide the first proof that p-BQ is a cause of hypoxia in smokers. We also show that although both p-BQ and CO are responsible for causing hypoxia in smokers, exposure to CO further affects the function over and above that produced by Hb-p-BQ adduct.

Adequately diversified dietary intake and iron and folic acid supplementation during pregnancy is associated with reduced occurrence of symptoms suggestive of pre-eclampsia or eclampsia in Indian women

Background/Objective

Pre-eclampsia or Eclampsia (PE or E) accounts for 25% of cases of maternal mortality worldwide. There is some evidence of a link to dietary factors, but few studies have explored this association in developing countries, where the majority of the burden falls. We examined the association between adequately diversified dietary intake, iron and folic acid supplementation during pregnancy and symptoms suggestive of PE or E in Indian women.

Methods

Cross-sectional data from India’s third National Family Health Survey (NFHS-3, 2005-06) was used for this study. Self-reported symptoms suggestive of PE or E during pregnancy were obtained from 39,657 women aged 15-49 years who had had a live birth in the five years preceding the survey. Multivariable logistic regression analysis was used to estimate the association between adequately diversified dietary intake, iron and folic acid supplementation during pregnancy and symptoms suggestive of PE or E after adjusting for maternal, health and lifestyle factors, and socio-demographic characteristics of the mother.

Results

In their most recent pregnancy, 1.2% (n=456) of the study sample experienced symptoms suggestive of PE or E. Mothers who consumed an adequately diversified diet were 34% less likely (OR: 0.66; 95% CI: 0.51-0.87) to report PE or E symptoms than mothers with inadequately diversified dietary intake. The likelihood of reporting PE or E symptoms was also 36% lower (OR: 0.64; 95% CI: 0.47-0.88) among those mothers who consumed iron and folic acid supplementation for at least 90 days during their last pregnancy. As a sensitivity analysis, we stratified our models sequentially by education, wealth, antenatal care visits, birth interval, and parity. Our results remained largely unchanged: both adequately diversified dietary intake and iron and folic acid supplementation during pregnancy were associated with a reduced occurrence of PE or E symptoms.

Conclusion

Having a adequately diversified dietary intake and iron and folic acid supplementation in pregnancy was associated with a reduced occurrence of symptoms suggestive of PE or E in Indian women.

Placental pathology in smoking and non-smoking preeclamptic women

OBJECTIVE

To ascertain whether the protective effect of smoking during preeclampsia (PE) can be visualized in the placenta.

METHODS

The study cohort consisted of placentas (n = 523) from pregnancies complicated by PE, delivered at Karolinska University Hospital in Stockholm during the period 2000-2009. Of the women included in the study, 488 were non-smokers and 35 were smokers at first visit to maternity care. Outcome variables were placental infarctions and decidual arteriopathy.

RESULTS

Infarctions (affecting ≥5% of the placental tissue) were found in 15.6% of the placentas from non-smokers and in 25.7% of the placentas from smokers (OR 1.88: CI 0.84-4.16, p = 0.12). Decidual arteriopathy was found in 27.5% of the placentas from non-smokers and in 40.0% of the placentas from smokers (1.76: CI 0.87-3.56, p = 0.12). When diagnosed histopathologically, placental abruption was found in 15.4% among non-smokers and in 17.1% among smokers (1.14: CI 0.46-2.84, p = 0.98). Those differences did not show any statistical significance.

CONCLUSION

No significant differences concerning placental infarctions, decidual arteriopathy or abruption were found between preeclamptic placentas from non-smokers compared to smokers.

Oxidative stress markers in hypertensive states of pregnancy: preterm and term disease

Discussion continues as to whether de novo hypertension in pregnancy with significant proteinuria (pre-eclampsia; PE) and non-proteinuric new hypertension (gestational hypertension; GH) are parts of the same disease spectrum or represent different conditions. Non-pregnant hypertension, pregnancy and PE are all associated with oxidative stress. We have established a 6 weeks postpartum clinic for women who experienced a hypertensive pregnancy. We hypothesized that PE and GH could be distinguished by markers of oxidative stress; thiobarbituric acid reactive substances (TBARS) and antioxidants (ferric ion reducing ability of plasma; FRAP). Since the severity of PE and GH is greater pre-term, we also compared pre-term and term disease. Fifty-eight women had term PE, 23 pre-term PE, 60 had term GH and 6 pre-term GH, 11 pre-existing (essential) hypertension (EH) without PE. Limited data were available from normotensive pregnancies (n = 7) and non-pregnant controls (n = 14). There were no differences in postpartum TBARS or FRAP between hypertensive states; TBARS (P = 0.001) and FRAP (P = 0.009) were lower in plasma of non-pregnant controls compared to recently-pregnant women. Interestingly FRAP was higher in preterm than term GH (P = 0.013). In PE and GH, TBARS correlated with low density lipoprotein (LDL)-cholesterol (P = 0.036); this association strengthened with inclusion of EH (P = 0.011). The 10 year Framingham index for cardiovascular risk was positively associated with TBARS (P = 0.003). Oxidative stress profiles do not differ between hypertensive states but appear to distinguish between recently-pregnant and non-pregnant states. This suggests that pregnancy may alter vascular integrity with changes remaining 6 weeks postpartum. LDL-cholesterol is a known determinant of oxidative stress in cardiovascular disease and we have shown this association to be present in hypertensive pregnancy further emphasizing that such a pregnancy may be revealing a pre-existing cardiovascular risk.

Effects of maternal tobacco-smoke exposure on fetal growth and neonatal size

Exposure to tobacco smoke, through both active and passive measures, has a significant impact on women's health, including effects on the cardiovascular, pulmonary and reproductive systems. Of particular interest is the effect of smoking on pregnancy outcomes. One crucial outcome that has been linked to the subsequent development of both neonatal and adult disease is intrauterine or fetal growth restriction. In this article, we will summarize the effects of smoking on newborn size and fetal growth. We will review evidence showing that tobacco consumption during pregnancy leads to a reduction in birthweight, largely through affecting specific anthropometric measures and newborn body composition. We will highlight the role of genetic susceptibility to these effects and discuss how smoking cessation prior to the third trimester results in a reduction in the risk of fetal growth restriction.

Smoking during pregnancy: changes in mid-gestation angiogenic factors in women at risk of developing preeclampsia according to uterine artery Doppler findings

OBJECTIVES

To ascertain whether angiogenic factors are altered in smokers at increased risk of preeclampsia (PE) according to uterine artery Doppler (UAD) assessment.

METHODS

Uterine artery mean pulsatility index (PI), maternal placental growth factor (PlGF), and soluble fms-like tyrosine kinase-1 (sFlt-1) serum levels were measured in 125 healthy pregnant women at 24 weeks of gestation. Smoking status was determined based on cotinine levels in maternal blood.

RESULTS

Smokers had significantly higher PlGF concentration compared with nonsmokers [median PlGF levels: 575 (511) vs. 277 (259) pg/mL, respectively, p = 0.001]. The differences in PlGF levels were also observed between smokers and nonsmokers within the group of women with abnormal UAD and therefore at high risk of developing PE [median PlGF levels: 472 (434) vs. 235 (169) pg/mL, respectively, p = 0.0005]. In our patient cohort, 16 women developed PE (12.8%), of whom only 3 were smokers [odds ratios (ORs): 0.49; 95% confidence interval (CI) (0.13-1.84)]. In patients who finally developed intrauterine growth restriction, the PlGF/sFlt-1 ratio was significantly higher in the group of smokers compared with that of nonsmokers [0.39 (0.28) vs. 0.13 (0.21), respectively, p = 0.0311].

CONCLUSION

The effect of smoking in reducing the risk of PE may be due to the increase of PlGF and PlGF/sFlt-1 ratio in maternal blood, even among women with abnormal UAD.

[Medical assessment after a pre-eclampsia: why? for whom? when? how? for what purpose?]

The internist has a relevant role in the medical assessment which is mandatory after every case of pre-eclampsia. This postnatal visit has to be performed to assert there is no underlying disorder such as chronic arterial hypertension or nephropathy, autoimmune disease or thrombophilia. This visit is also needed to provide information to the woman about what occurred during the pregnancy as well as to consider which would have to be done in case of a subsequent pregnancy. Long-term outcome had also to be taken into account considering risks for cardiac, arterial, renal and metabolic diseases. This visit is of outmost importance after very early-onset pre-eclampsia, and especially if it has already occurred. The postnatal visit after pre-eclampsia represents a very demonstrative example of the role that the internist can afford to the obstetrician in the management of medical disorders occurring during pregnancy and needing a specific expertise as well as a long-term follow-up.

Maternal smoking and blood pressure in different trimesters of pregnancy: the Generation R study

OBJECTIVE

Smoking during pregnancy is a risk factor for various adverse birth outcomes but lowers the risk of preeclampsia. Cardiovascular adaptations might underlie these associations. We examined the associations of smoking in different trimesters of pregnancy with repeatedly measured blood pressure and the risks of preeclampsia and pregnancy-induced hypertension in a low-risk population-based cohort of 7106 pregnant women.

METHODS

This study was embedded in a population-based prospective cohort study from early pregnancy onwards. Smoking and systolic and diastolic blood pressures were assessed by questionnaires and physical examinations in each trimester of pregnancy. Information about preeclampsia and pregnancy-induced hypertension was obtained from medical records.

RESULTS

Compared to nonsmoking women, both first-trimester-only and continued smoking were associated with a steeper increase for systolic blood pressure and a lowest mid-pregnancy level and steeper increase thereafter for diastolic blood pressure throughout pregnancy. We did not find any significant associations in risk of preeclampsia for first-trimester-only smoking (odds ratio of 1.28, 95% confidence interval 0.74, 2.21) and continued smoking (odds ratio of 0.83, 95% confidence interval 0.50, 1.36), respectively.

CONCLUSIONS

Our results suggest that both first-trimester-only and continued smoking are associated with persistent maternal cardiovascular adaptations during pregnancy. Strategies for prevention of smoking during pregnancy should be focused on the preconception period. The effects of early and late-pregnancy smoking on the risk of preeclampsia should be further explored. Our results should be carefully interpreted to the general population of pregnant women.

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.

Benzopyrene and experimental stressors cause compensatory differentiation in placental trophoblast stem cells

Stress causes decreased cell accumulation in early periimplantation embryos and the placental trophoblast stem cells derived from them. Benzopyrene and many other stressors activate stress enzymes that lead to suppressed stem cell accumulation through diminished proliferation and increased apoptosis. Trophoblast stem cells proliferate and a subpopulation of early postimplantation trophoblast cells differentiate to produce the first placental hormones that arise in the implanting conceptus. These hormones mediate antiluteolytic effects that enable the continuation of a successful implantation. The normal determination and differentiation of placental trophoblast stem cells is dependent upon a series of transcription factors. But, these transcription factors can also be modulated by stress through the activity of stress enzymes. This review enumerates and analyzes recent reports on the effects of benzopyrene on placental function in terms of the emerging paradigm that placental differentiation from stem cells can be regulated when insufficient production of stem cells is caused by stress. In addition, we review the other effects caused by benzopyrene throughout placental development.