The interval between pregnancies and the risk of preeclampsia

Persistent Maternal Cardiac Dysfunction After Preeclampsia Identifies Patients at Risk for Recurrent Preeclampsia

The purpose of our study was to assess cardiac function in nonpregnant women with previous early preeclampsia before a second pregnancy to highlight the cardiovascular pattern, which may take a risk for recurrent preeclampsia. Seventy-five normotensive patients with previous preeclampsia and 147 controls with a previous uneventful pregnancy were enrolled in a case-control study and submitted to echocardiographic examination in the nonpregnant state 12 to 18 months after the first delivery. All patients included in the study had pregnancy within 24 months from the echocardiographic examination and were followed until term. Twenty-two (29%) of the 75 patients developed recurrent preeclampsia. In the nonpregnant state, patients with recurrent preeclampsia compared with controls and nonrecurrent preeclampsia had lower stroke volume (63 ± 14 mL versus 73 ± 12 mL and 70 ± 11 mL, P<0.05), cardiac output (4.6 ± 1.2 L versus 5.3 ± 0.9 L and 5.2 ± 1.0 L, P<0.05), higher E/E' ratio (11.02 ± 3.43 versus 7.34 ± 2.11 versus 9.03 ± 3.43, P<0.05), and higher total vascular resistance (1638 ± 261 dyne · s(-1) · cm(-5) versus 1341 ± 270 dyne · s(-1) · cm(-5) and 1383 ± 261 dyne · s(-1) · cm(-5), P<0.05). Left ventricular mass index was higher in both recurrent and nonrecurrent preeclampsia compared with controls (30.0 ± 6.3 g/m(2.7) and 30.4 ± 6.8 g/m(2.7) versus 24.8 ± 5.0 g/m(2.7), P<0.05). Signs of diastolic dysfunction and different left ventricular characteristics are present in the nonpregnant state before a second pregnancy with recurrent preeclampsia. Previous preeclamptic patients with nonrecurrent preeclampsia show left ventricular structural and functional features intermediate with respect to controls and recurrent preeclampsia.

Predictive Value of the sFlt-1:PlGF Ratio in Women with Suspected Preeclampsia

BACKGROUND

The ratio of soluble fms-like tyrosine kinase 1 (sFlt-1) to placental growth factor (PlGF) is elevated in pregnant women before the clinical onset of preeclampsia, but its predictive value in women with suspected preeclampsia is unclear.

METHODS

We performed a prospective, multicenter, observational study to derive and validate a ratio of serum sFlt-1 to PlGF that would be predictive of the absence or presence of preeclampsia in the short term in women with singleton pregnancies in whom preeclampsia was suspected (24 weeks 0 days to 36 weeks 6 days of gestation). Primary objectives were to assess whether low sFlt-1:PlGF ratios (at or below a derived cutoff) predict the absence of preeclampsia within 1 week after the first visit and whether high ratios (above the cutoff) predict the presence of preeclampsia within 4 weeks.

RESULTS

In the development cohort (500 women), we identified an sFlt-1:PlGF ratio cutoff of 38 as having important predictive value. In a subsequent validation study among an additional 550 women, an sFlt-1:PlGF ratio of 38 or lower had a negative predictive value (i.e., no preeclampsia in the subsequent week) of 99.3% (95% confidence interval [CI], 97.9 to 99.9), with 80.0% sensitivity (95% CI, 51.9 to 95.7) and 78.3% specificity (95% CI, 74.6 to 81.7). The positive predictive value of an sFlt-1:PlGF ratio above 38 for a diagnosis of preeclampsia within 4 weeks was 36.7% (95% CI, 28.4 to 45.7), with 66.2% sensitivity (95% CI, 54.0 to 77.0) and 83.1% specificity (95% CI, 79.4 to 86.3).

CONCLUSIONS

An sFlt-1:PlGF ratio of 38 or lower can be used to predict the short-term absence of preeclampsia in women in whom the syndrome is suspected clinically. (Funded by Roche Diagnostics.).

Determination of Risk Factors for Pre-eclampsia and Eclampsia in a Tertiary Hospital of India: A Case Control Study

BACKGROUND

Preeclampsia and eclampsia (PE) are pregnancy specific syndromes that contribute to maternal and fetal morbidity and mortality. The identification of its predisposing factors in the pre-pregnancy and initial stage of pregnancy will help in reducing the morbidity and mortality.

AIM

The aim of this study is to determine the risk factors for PE among pregnant women in a tertiary level hospital.

MATERIALS AND METHODS

In this study, 122 women who delivered beyond 22 weeks of gestation and diagnosed as preeclampsia or eclampsia were selected. Simultaneously, 122 controls with no diagnosis of preeclampsia or eclampsia were selected from the post natal ward. Cases and controls were administered the same pre-tested questionnaire containing different risk factors.

RESULTS AND CONCLUSION

Logistic regression was applied in the statistical analysis. The factors that were found to be significant predictors of risk for development of PE were family history of preeclampsia (adjusted odds ratio [OR] 18.57 [1.93-178.16], P = 0.011), higher calorie intake (adjusted OR 14.12 [6.41-43.23] body mass index (adjusted P < 0.001), employment (adjusted OR 6.35 [1.56-25.82] P = 0.010], less protein intake (adjusted OR 3.87 [1.97-8.01] P < 0.001), increased OR 5.86 [02.48-13.8] P < 0.001), mild physical activities (adjusted OR 3.46 [1.06-11.24] P = 0.039). Past history of hypertension and diabetes mellitus were also associated with development of PE.

The Impact of Multiparity on Uterine Gene Expression and Decidualization in Mice

It has been well established that a previous pregnancy exhibits a beneficial effect on the subsequent pregnancy. However, the underlying mechanisms have not been defined. We hypothesized that multiparity may affect decidualization process during early pregnancy. To test this hypothesis, we analyzed global gene changes associated with multiparity in the mouse uterus using RNA-sequencing (RNA-seq). We identified a total of 131 differentially expressed genes (fold change > 2 and false discovery rate < 0.05), of which 58 were downregulated and 73 genes were upregulated in the second pregnancy (SP) compared to the first pregnancy. Functional clustering analysis showed that genes involved in stress response were significantly enriched. Most importantly, a significant portion of differentially expressed genes, 14 genes or 10.7%, overlapped with the gene list associated with decidualization. Quantitative reverse transcription (RT) polymerase chain reaction (qRT-PCR) analysis confirmed a decreased expression of 4 genes (Klk1, kallikrein 1; H2-Eb1, histocompatibility 2 class II antigen E beta; Mmp7, matrix metallopeptidase 7; Pdpn, podoplanin) and an increase in expression of 2 genes (Thy1, thymus cell antigen 1; Ptgs2, prostaglandin-endoperoxide synthase 2) in SP. Beyond protein-coding genes, we also identified a differentially expressed long noncoding RNA AI506816. Our data provide new insights into the molecular mechanisms underlying the beneficial effect of multiparity.

Induced Abortions and the Risk of Preeclampsia Among Nulliparous Women

Induced abortion (IA) has been associated with a lower risk of preeclampsia among nulliparous women, but it remains unclear whether this association differs by method (either surgical or medical) or timing of IA. We performed a nested case-control study of 12,650 preeclampsia cases and 50,600 matched control deliveries identified in the Medical Birth Register of Finland from 1996 to 2010. Data on number, method, and timing of IAs were obtained through a linkage with the Registry of Induced Abortions. Odds ratios and 95% confidence intervals were calculated. Overall, prior IA was associated with a lower risk of preeclampsia, with odds ratios of 0.9 (95% confidence interval (CI): 0.9, 1.0) for 1 prior IA and 0.7 (95% CI: 0.5, 1.0) for 3 or more IAs. Differences in the associations between IA and preeclampsia by timing and method of IA were small, with odds ratios of 0.8 (95% CI: 0.6, 1.1) for late (≥12 gestation weeks) surgical abortion and 0.9 (95% CI: 0.7, 1.2) for late medical abortion. There was no association between IA in combination with a history of spontaneous abortion and risk of preeclampsia. In conclusion, prior IA only was associated with a slight reduction in the risk of preeclampsia.

Increased planned delivery contributes to declining rates of pregnancy hypertension in Australia: a population-based record linkage study

OBJECTIVE

Since the 1990s, pregnancy hypertension rates have declined in some countries, but not all. Increasing rates of early planned delivery (before the due date) have been hypothesised as the reason for the decline. The aim of this study was to explore whether early planned delivery can partly explain the declining pregnancy hypertension rates in Australia.

DESIGN

Population-based record linkage study utilising linked birth and hospital records.

SETTING AND PARTICIPANTS

A cohort of 1,076,122 deliveries in New South Wales, Australia, 2001-2012.

OUTCOME MEASURES

Pregnancy hypertension (including gestational hypertension, pre-eclampsia and eclampsia) was the main outcome; pre-eclampsia was a secondary outcome.

RESULTS

From 2001 to 2012, pregnancy hypertension rates declined by 22%, from 9.9% to 7.7%, and pre-eclampsia by 27%, from 3.3% to 2.4% (trend p<0.0001). At the same time, planned deliveries increased: prelabour caesarean section by 43% (12.9-18.4%) and labour inductions by 10% (24.8-27.2%). Many maternal risk factors for pregnancy hypertension significantly increased (p<0.01) over the study period including nulliparity, age ≥35 years, diabetes, overweight and obesity, and use of assisted reproductive technologies; some risk factors decreased including multifetal pregnancies, age <20 years, autoimmune diseases and previous pregnancy hypertension. Given these changes in risk factors, the pregnancy hypertension rate was predicted to increase to 10.5%. Examination of annual gestational age distributions showed that pregnancy hypertension rates actually declined from 38 weeks gestation and were steepest from 41 weeks; at least 36% of the decrease could be attributed to planned deliveries. The risk factors for pregnancy hypertension were also risk factors for planned delivery.

CONCLUSIONS

It appears that an unanticipated consequence of increasing early planned deliveries is a decline in the incidence of pregnancy hypertension. Women with risk factors for hypertension were relatively more likely to be selected for early delivery.

Assessment of angiogenesis modulators in pregnant women with pre-eclampsia: a case-control study

PURPOSE

This study aimed to evaluate the serum concentration of factors associated with placental angiogenesis in pre-eclamptic and normotensive pregnant women.

METHODS

This was a prospective, cross-sectional, case-control study in which the pro-angiogenic factors PlGF, VEGF and IL-10, and the anti-angiogenic factors IL-6, IL-17 and TNF-α of 55 pregnant women (31 with pre-eclampsia-PE and 24 normotensive), with gestational age ≥20 weeks, were measured in maternal blood through the enzyme-linked immunosorbent assay (ELISA). The Mann-Whitney and Kruskal-Wallis tests were used for comparison between groups.

RESULTS

Serum PIGF was reduced in the group of pregnant women with PE when compared with the normotensive women (493.2 ± 55.1 pg/mL vs. 4.4 ± 26.5 pg/mL; p < 0.001). There was no significant difference in PlGF levels in the pre-eclamptic pregnant women in relation to gestational age or proteinuria levels (p > 0.05). The serum levels of VEGF, IL-17, IL-10 and TNF-α were lower in the pregnant women with PE when compared with their normotensive peers, while the IL-6 levels were higher; however, this difference was not statistically significant (p > 0.05).

CONCLUSION

Serum PlGF levels were reduced in the pregnant women with PE and were unrelated to disease severity. Serum levels of VEGF, IL-17, IL-10 and TNF-α were reduced in the pre-eclamptic pregnant women when compared with their normotensive peers, without statistically significant differences.

Obstetric and neonatal outcome of pregnancies fathered by males on immunosuppression after solid organ transplantation

Immunosuppressive drugs may influence spermatogenesis, but little is known about outcome of pregnancies fathered by transplanted males. We estimated risk of adverse outcomes in pregnancies (with data after the first trimester) fathered by males that had undergone organ transplantation and were treated with immunosuppression. A population-based study, linking data from the Norwegian transplant registry and the Medical Birth Registry of Norway during 1967-2009 was designed. All Norwegian men undergoing solid organ transplantation were included. Odds ratios for major malformations, preeclampsia, preterm delivery (<37 weeks) and small-for-gestational-age were obtained using logistic regression. A total of 2463 transplanted males, fathering babies of 4614 deliveries before and 474 deliveries after transplantation were identified. The risk of preeclampsia was increased (AOR: 7.4, 95% CI: 1.1-51.4,) after transplantation compared to prior to transplantation. No increased risk was found for congenital malformations or other outcomes when compared with pregnancies before transplantation or with the general population (2 511 506 births). Our results indicate an increased risk of preeclampsia mediated through the transplanted and immunosuppressed father. Importantly, no increased risk was found for other adverse obstetric outcomes or malformations, which may reassure male transplant recipients planning to father children.

Pregnancy induces persistent changes in vascular compliance in primiparous women

OBJECTIVE

Pregnancy induces rapid, progressive, and substantial changes to the cardiovascular system. The low recurrence risk of preeclampsia, despite familial predisposition, suggests an adaptation associated with pregnancy that attenuates the risk for subsequent preeclampsia. We aimed to evaluate the persistent effect of pregnancy on maternal cardiovascular physiology.

STUDY DESIGN

Forty-five healthy nulliparous women underwent baseline cardiovascular assessment before conception and repeated an average of 30 months later. After baseline evaluation, 17 women conceived singleton pregnancies and all delivered at term. The remaining 28 women comprised the nonpregnant control group. We measured mean arterial blood pressure, cardiac output, plasma volume, pulse wave velocity, uterine blood flow, and flow-mediated vasodilation at each visit.

RESULTS

There was a significant decrease in mean arterial pressure from the prepregnancy visit to postpartum in women with an interval pregnancy (prepregnancy, 85.3±1.8; postpartum, 80.5±1.8 mm Hg), with no change in nonpregnant control subjects (visit 1, 80.3±1.4; visit 2, 82.8±1.4 mm Hg) (P=.002). Pulse wave velocity was significantly decreased in women with an interval pregnancy (prepregnancy, 2.73±0.05; postpartum, 2.49±0.05 m/s), as compared with those without an interval pregnancy (visit 1, 2.56±0.04; visit 2, 2.50±0.04 m/s) (P=.005). We did not observe a residual effect of pregnancy on cardiac output, plasma volume, uterine blood flow, or flow-mediated vasodilation.

CONCLUSION

Our observations of decreased mean arterial pressure and reduced arterial stiffness following pregnancy suggest a significant favorable effect of pregnancy on maternal cardiovascular remodeling. These findings may represent a mechanism by which preeclampsia risk is reduced in subsequent pregnancies.

Prior cesarean section is associated with increased preeclampsia risk in a subsequent pregnancy

Background

To evaluate the impact of a prior cesarean section on preeclampsia risk in a subsequent pregnancy.

Methods

Study data were collected from the Korea National Health Insurance Claims Database of the Health Insurance Review and Assessment Service for 2006–2010. Patients who had their first delivery in 2006 and subsequent delivery between 2007 and 2010 in Korea were enrolled. The overall incidence of preeclampsia during the second pregnancy was estimated and to evaluate the risk of preeclampsia in the second pregnancy, a model of multivariate logistic regression analysis was performed with preeclampsia as the final outcome

Results

The risk of preeclampsia in any pregnancy was 2.17%; the risk in the first pregnancy was 2.76%, and that in the second pregnancy was 1.15%. During the second pregnancy, the risk of preeclampsia was 13.30% for women who had developed preeclampsia in their first pregnancy and 0.85% for those who had not. In the entire population, prior cesarean section was associated with preeclampsia risk in their subsequent pregnancy (odds ratio [OR], 1.26; 95% confidence interval [CI], 1.13–1.41). Among women with and without preeclampsia in their first pregnancy, a prior cesarean section was associated with preeclampsia risk in their second pregnancy (OR, 1.35; 95% CI, 1.09–1.67; OR, 1.23; 95% CI, 1.08–1.40, respectively).

Conclusions

Our study showed that cesarean section in a first pregnancy was associated with increased preeclampsia risk in the second pregnancy. These results provide physicians with a preeclampsia risk evaluation method for a second pregnancy that they may aid counseling in patients.

Change in paternity, risk of placental abruption and confounding by birth interval: a population-based prospective cohort study in Norway, 1967-2009

OBJECTIVES

We examined abruption risk in relation to change in paternity, and evaluated if birth interval confounds this association.

SETTING

Population-based study of singleton births in Norway between 1967 and 2009.

PARTICIPANTS

Women who had their first two (n=747 566) singleton births in the Norwegian Medical Birth Registry. The associations between partner change between pregnancies and birth interval were examined in relation to abruption in a series of logistic regression models.

PRIMARY OUTCOME MEASURES

Risk, as well as unadjusted and adjusted OR of placental abruption in relation to change in paternity and interval between births.

RESULTS

Among women without abruption in their first pregnancy, the risks of abruption in the second pregnancy were 4.7 and 6.5 per 1000 in women who had the same and different partners, respectively (OR=1.39, 95% CI 1.26 to 1.53). After adjustments for confounders including birth interval and smoking, partner change was not associated with abruption (OR=1.01, 95% CI 0.79 to 1.32). Among women with abruption in the first pregnancy, the association between partner change and abruption in the second pregnancy was 0.98 (95% CI 0.75 to 1.28). Interval <1 year was associated with increased abruption risk in the second pregnancy among women with the same as well as different partners, but interval over 4 years was only associated with increased risk among women with the same partner. No such patterns were seen for recurrent abruption.

CONCLUSIONS

We find no evidence that a change in partner is associated with increased abruption risk. Theories supporting an immune maladaptation hypothesis afforded by change in paternity are not supported insofar as abruption is concerned.

HLA Class Ib Molecules and Immune Cells in Pregnancy and Preeclampsia

Despite decades of research, the highly prevalent pregnancy complication preeclampsia, “the disease of theories,” has remained an enigma. Indeed, the etiology of preeclampsia is largely unknown. A compiling amount of studies indicates that the pathological basis involves a complex array of genetic predisposition and immunological maladaptation, and that a contribution from the mother, the father, and the fetus is likely to be important. The Human Leukocyte Antigen (HLA)-G is an increasing focus of research in relation to preeclampsia. The HLA-G molecule is primarily expressed by the extravillous trophoblast cells lining the placenta together with the two other HLA class Ib molecules, HLA-E and HLA-F. Soluble isoforms of HLA-G have been detected in the early endometrium, the matured cumulus–oocyte complex, maternal blood of pregnant women, in umbilical cord blood, and lately, in seminal plasma. HLA-G is believed to be involved in modulating immune responses in the context of vascular remodeling during pregnancy as well as in dampening potential harmful immune attacks raised against the semi-allogeneic fetus. In addition, HLA-G genetic variants are associated with both membrane-bound and soluble forms of HLA-G, and, in some studies, with preeclampsia. In this review, a genetic contribution from the mother, the father, and the fetus, together with the presence and function of various immune cells of relevance in pregnancy are reviewed in relation to HLA-G and preeclampsia.

Preeclampsia and maternal cardiovascular disease: consequence or predisposition?

Formerly preeclamptic women stand a higher chance of developing cardiovascular disease (CVD) later in life and may experience a shortened life span. This review updates the pathophysiology and definition of this complex disease and highlights the protective role of pregnancy by considering the relationship between pregnancy interval and likelihood of disease recurrence. The evidence for persistent maternal cardiovascular impairment following preeclampsia (PE) is considered, e.g. postpartum changes in CVD occurrence, blood pressure elevation and changes in the renin-angiotensin-aldosterone system). Since maternal endothelial dysfunction is a hallmark of PE, we summarize the evidence for reduced flow-mediated dilation in women with previous PE, and consider the utility and shortcomings of this clinical measure. In addition to viewing postpartum changes as a consequence of this disease, we consider the alternative view that PE might be the manifestation of a maternal phenotype that already has some predisposition to or is in the earlier stages of CVD; in this case, some of the postpartum residual deficits (or their antecedents) may have already been present prior to pregnancy. Finally, we consider the use of novel biomarkers for predicting or detecting PE prior to the appearance of clinical symptoms.

Increased risk of autism spectrum disorders at short and long interpregnancy intervals in Finland

OBJECTIVE

Both short and long interpregnancy intervals (IPI) are believed to present possible adverse conditions for fetal development. Short IPI has recently been associated with increased risk of autism, but whether long IPI increases risk for autism spectrum disorders (ASD) has not been thoroughly investigated. We investigated the association between short and long IPI in a Finnish population-based study.

METHOD

This study was conducted in the Finnish Prenatal Study of Autism, which is based in a national birth cohort. Children born in Finland in 1987 to 2005 and diagnosed with ASD by 2007 were identified through the Finnish Hospital Discharge Register. A total of 2,208 non-firstborn patients with ASD and 5,163 matched controls identified from the Finnish Medical Birth Register were included in the primary analysis. The association between IPI and ASD was determined using conditional logistic regression and adjusted for potential confounders.

RESULTS

Relative to births with an IPI of 24 to 59 months, those with the shortest IPI (<12 months) had an increased risk of ASD (odds ratio [OR] = 1.50, 95% CI = 1.28, 1.74) in confounder-adjusted models, whereas the ORs for longer IPI births (60-119 months and ≥120 months) were 1.28 (95% CI = 1.08, 1.52) and 1.44 (95% CI = 1.12, 1.85), respectively.

CONCLUSION

This study provides evidence that risk of ASD is increased at long as well as short IPI.

Validity of pre-eclampsia registration in the medical birth registry of norway for women participating in the norwegian mother and child cohort study, 1999-2010

BACKGROUND

The Norwegian Mother and Child Cohort Study (MoBa), a prospective population-based pregnancy cohort, is a valuable database for studying causes of pre-eclampsia. Pre-eclampsia data in MoBa come from the Medical Birth Registry of Norway (MBRN); thus, we wanted to study the validity of MBRN pre-eclampsia registration for MoBa women.

METHODS

We selected all MoBa pregnancies with pre-eclampsia registered in the MBRN (n = 4081) and a random control group (n = 2000) without pre-eclampsia registrations. After excluding two delivery units not participating in MoBa and one no longer operating, units were asked to provide copies of antenatal charts with blood pressure and urinary measurements from all antenatal visits during pregnancy, and hospital discharge codes from the delivery stay. We received data for 5340 pregnancies delivered 1999-2010 (87% of all eligible). We calculated positive predictive value (PPV), and sensitivity and specificity of MBRN registration, using hypertension and proteinuria on the antenatal charts and/or hospital discharge codes indicating pre-eclampsia as gold standard.

RESULTS

Overall PPV was 83.9% [95% CI 82.7, 85.1] and was higher when women were primiparous, or delivered preterm or low birthweight infants. Severe pre-eclampsia in the MBRN was found to be a true severe pre-eclampsia in 70% of cases. Extrapolating to the total MoBa population, the estimated sensitivity was low - 43.0% (38.7, 48.2) - while specificity was high - 99.2% (99.2, 99.3). False negative cases seemed to have mild forms of pre-eclampsia.

CONCLUSIONS

PPV and specificity of pre-eclampsia registration in the MBRN during 1999-2010 was satisfactory, while sensitivity was low.

Pre-eclampsia and assisted reproductive technologies: consequences of advanced maternal age, interbirth intervals, new partner and smoking habits

OBJECTIVE

To examine the risk of pre-eclampsia (PE) in women conceiving after assisted reproductive technologies (ART). Potential confounding from maternal age, long intervals between births, new partner and smoking were evaluated.

DESIGN AND SETTING

Population-based cohort study with data from the Medical Birth Registry of Norway.

POPULATION

A total of 501,766 mothers with offspring from 1988 to 2009.

METHODS

Births to the same mother were linked in sibship data files with information of ART.

MAIN OUTCOME MEASURES

Odds ratio (OR) (95% confidence intervals) of PE in pregnancies conceived by ART compared with spontaneous conception, stratified by parity.

RESULTS

The prevalence of PE was 5.1% in first, 2.2% in second and 2.1% in third pregnancies. Corresponding figures in ART pregnancies were 6.0%, 3.3% and 4.4%. Hence, the odds ratios of PE in ART pregnancies relative to spontaneous pregnancies increased from 1.2 (1.1-1.3) in first, 1.5 (1.3-1.8) in second to 2.1 (1.4-3.3) in third pregnancies. Adjusting by maternal age lowered the odds ratio to 1.3 (1.1-1.6) and 1.8 (1.2-2.8) in second and third pregnancies, respectively. Multi-adjusted, birth interval had more impact than change of partner. Smoking was associated with a strongly reduced PE risk (odds ratio 0.65; 0.62-0.69), but there was no confounding by smoking on the ART associated risk.

CONCLUSIONS

Assisted reproductive technologies increases the risk of PE, and the risk may increase by parity. The association between ART pregnancies and PE is to some extent explained by interbirth intervals and advanced maternal age, but not to change of partner or smoking.

Regulatory T cells: new keys for further unlocking the enigma of fetal tolerance and pregnancy complications

The immunological alterations required for successful pregnancy in eutherian placental mammals have remained a scientific enigma since the discovery of MHC haplotype diversity and unique immune signatures among individuals. Within the past 10 years, accumulating data suggest that immune-suppressive regulatory T cells (Tregs) confer essential protective benefits in sustaining tolerance to the semiallogeneic fetus during pregnancy, along with their more established roles in maintaining tolerance to self and "extended self" commensal Ags that averts autoimmunity. Reciprocally, many human pregnancy complications stemming from inadequacies in fetal tolerance have been associated with defects in maternal Tregs. Thus, further elucidating the immunological shifts during pregnancy not only have direct translational implications for improving perinatal health, they have enormous potential for unveiling new clues about how Tregs work in other biological contexts. In this article, epidemiological data in human pregnancy and complementary animal studies implicating a pivotal protective role for maternal Tregs are summarized.

Epidemiology of ischemic placental disease: a focus on preterm gestations

Preeclampsia, placental abruption, and intrauterine growth restriction (IUGR) have collectively been termed ischemic placental disease (IPD) due to a suspected common biological pathway involving poor placentation in early pregnancy and subsequent placental insufficiency. Despite decades of research, the etiologies of these conditions remain largely unknown and preventive and therapeutic strategies are lacking. It has been suggested that the underpinnings of IPD lie primarily in preterm gestations and that classification of these conditions based on the gestational age at onset will facilitate etiologic research. The purpose of this review is to describe our current knowledge regarding the risk factors, co-occurrence, and recurrence of the conditions of IPD with a specific focus on the preterm gestational window.

Perfluoroalkyl substances during pregnancy and validated preeclampsia among nulliparous women in the Norwegian Mother and Child Cohort Study

Perfluoroalkyl substances (PFAS) are persistent and ubiquitous environmental contaminants, and human exposure to these substances may be related to preeclampsia, a common pregnancy complication. Previous studies have found serum concentrations of PFAS to be positively associated with pregnancy-induced hypertension and preeclampsia in a population with high levels of exposure to perfluorooctanoate. Whether this association exists among pregnant women with background levels of PFAS exposure is unknown. Using data from the Norwegian Mother and Child Cohort Study conducted by the Norwegian Institute of Public Health, we carried out a study of nulliparous pregnant women enrolled in 2003-2007 (466 cases, 510 noncases) to estimate associations between PFAS concentrations and an independently validated diagnosis of preeclampsia. We measured levels of 9 PFAS in maternal plasma extracted midpregnancy; statistical analyses were restricted to 7 PFAS that were quantifiable in more than 50% of samples. In proportional hazards models adjusted for maternal age, prepregnancy body mass index (weight (kg)/height (m)(2)), educational level, and smoking status, we observed no strongly positive associations between PFAS levels and preeclampsia. We found an inverse association between preeclampsia and the highest quartile of perfluoroundecanoic acid concentration relative to the lowest quartile (hazard ratio = 0.55, 95% confidence interval: 0.38, 0.81). Overall, our findings do not support an increased risk of preeclampsia among nulliparous Norwegian women with background levels of PFAS exposure.

Interbirth interval and history of previous preeclampsia: a case-control study among multiparous women

Background

Preeclampsia is a disorder with a reported incidence of 2%-8% among all pregnancies, accounting for more than 50,000 deaths worldwide each year. In low- and middle- income countries maternal/perinatal morbidity and mortality associated with preeclampsia are high due to the lack of proper prenatal and hospital care and limited access to neonatal intensive care. The objectives of our study were to determine the association of long interbirth interval (IBI) and preeclampsia and to investigate the interactions between long IBI and other risk factors among multiparous women in Yerevan, Armenia.

Methods

We conducted a hospital-based case–control study among 36 multiparous women with preeclampsia (cases) and 148 without preeclampsia (controls) during their last pregnancy, selected from the two largest maternity hospitals in Armenia. The data were collected through telephone-based structured interviews and analyzed using STATA software. The study applied univariate and multivariate logistic regression analyses.

Results

The study found a significant interaction between IBI and previous history of preeclampsia. Among women without a history of previous preeclampsia, the odds of having preeclampsia among women with long IBI (greater than or equal to five years) was 6.88 time higher compared to those with short IBI (CI: 1.75-27.05; p = 0.006) after adjusting for confounders; among women with a history of previous preeclampsia the odds ratio was 0.60 (CI: 0.07-4.99; p = 0.638). The final fitted model for preeclampsia among multiparous women who had planned their pregnancies included IBI, time to pregnancy, Body Mass Index, method of contraception and household monthly income.

Conclusions

Long IBI appeared to be a strong risk factor for preeclampsia development only among women without a history of previous preeclampsia. This finding may contribute to a new approach in understanding the etiology of preeclampsia and may be useful for developing further recommendations for this particular subgroup of women that are at higher risk for preeclampsia development in subsequent pregnancies.

Pre-eclampsia rates in the United States, 1980-2010: age-period-cohort analysis

OBJECTIVE

To estimate the contributions of biological aging, historical trends, and birth cohort effects on trends in pre-eclampsia in the United States.

DESIGN

Population based retrospective study.

SETTING

National hospital discharge survey datasets, 1980-2010, United States.

PARTICIPANTS

120 million women admitted to hospital for delivery.

MAIN OUTCOME MEASURES

Temporal changes in rates of mild and severe pre-eclampsia in relation to maternal age, year of delivery, and birth cohorts. Poisson regression as well as multilevel age-period-cohort models with adjustment for obesity and smoking were incorporated.

RESULTS

The rate of pre-eclampsia was 3.4%. The age-period-cohort analysis showed a strong age effect, with women at the extremes of maternal age having the greatest risk of pre-eclampsia. In comparison with women delivering in 1980, those delivering in 2003 were at 6.7-fold (95% confidence interval 5.6-fold to 8.0-fold) increased risk of severe pre-eclampsia. Period effects declined after 2003. Trends for severe pre-eclampsia also showed a modest birth cohort effect, with women born in the 1970s at increased risk. Compared with women born in 1955, the risk ratio for women born in 1970 was 1.2 (95% confidence interval 1.1 to 1.3). Similar patterns were also evident for mild pre-eclampsia, although attenuated. Changes in the population prevalence of obesity and smoking were associated with period and cohort trends in pre-eclampsia but did not explain the trends.

CONCLUSIONS

Rates of severe pre-eclampsia have been increasing in the United States and age-period-cohort effects all contribute to these trends. Although smoking and obesity have driven these trends, changes in the diagnostic criteria may have also contributed to the age-period-cohort effects. Health consequences of rising obesity rates in the United States underscore that efforts to reduce obesity may be beneficial to maternal and perinatal health.

Degree of fetal growth restriction associated with schizophrenia risk in a national cohort

BACKGROUND

Accumulating evidence suggests that fetal growth restriction may increase risk of later schizophrenia but this issue has not been addressed directly in previous studies. We examined whether the degree of fetal growth restriction was linearly related to risk of schizophrenia, and also whether maternal pre-eclampsia, associated with both placental dysfunction and poor fetal growth, was related to risk of schizophrenia.

METHOD

A population-based cohort of single live births in the Medical Birth Registry of Norway (MBRN) between 1967 and 1982 was followed to adulthood (n=873 612). The outcome was schizophrenia (n=2207) registered in the National Insurance Scheme (NIS). The degree of growth restriction was assessed by computing sex-specific z scores (standard deviation units) of ‘ birth weight for gestational age’ and ‘ birth length for gestational age’. Analyses were adjusted for potential confounders. Maternal pre-eclampsia was recorded in the Medical Birth Registry by midwives or obstetricians using strictly defined criteria.

RESULTS

The odds ratio (OR) for schizophrenia increased linearly with decreasing birth weight for gestational age z scores (p value for trend=0.005). Compared with the reference group (z scores 0.01–1.00), the adjusted OR [95% confidence interval (CI)] for the lowest z-score category (<x3.00) was 2.0 (95% CI 1.2–3.5). A similar pattern was observed for birth length for gestational age z scores. Forty-nine individuals with schizophrenia were identified among 15 622 births with pre-eclampsia. The adjusted OR for schizophrenia following maternal pre-eclampsia was 1.3 (95% CI 1.0–1.8).

CONCLUSIONS

Associations of schizophrenia risk with degree of fetal growth restriction and pre-eclampsia suggest future research into schizophrenia etiology focusing on mechanisms that influence fetal growth, including placental function.

Birth outcomes among offspring of adult cancer survivors: a population-based study

Do cancer and cancer treatment influence patients' subsequent pregnancies and outcomes for the offspring? In this study, we compared birth outcomes in 3,915 female and male survivors and 144,653 controls from the general population with similar parity, by merging data from the Cancer Registry and the Medical Birth Registry of Norway. The cancer survivors were diagnosed at age 16-45 in the period 1967-2004. Subgroups of nulliparous survivors (childless before cancer) and primiparous (one pregnancy before and one after cancer) were analyzed, using logistic regression to compare birth outcomes with controls, focusing perinatal death, congenital anomalies, preterm birth (<37 gestational weeks) and low birth weight (LBW, <2,500 g). We adjusted for maternal age, birth period and educational level. Nulliparous female survivors' offspring had increased risk of preterm birth (OR = 1.30 [95% CI 1.05-1.61]) but similar risks of LBW and perinatal death as their controls. Primiparous female survivors differed from their controls, with higher frequency of preterm birth (OR = 1.89 [95% CI 1.40-2.56]) and LBW at term (OR = 2.02 [95% CI 1.15-3.55]). A borderline significant increase of perinatal death was seen among offspring of primiparous female survivors, with OR = 1.92 (95% CI 0.98-3.76). Offspring of male survivors did not differ from their controls. For all cancer types combined, no increased risk of congenital anomalies was seen among either female or male survivors' offspring. Pregnant female cancer survivors should be offered close follow-up, as there is an increased risk of adverse birth outcomes, in particular among those with higher parities.

Serum trace elements levels in preeclampsia and eclampsia: correlation with the pregnancy disorder

Preeclampsia and eclampsia are fatal medical complications of pregnancy accounting for 20-80 % of increased maternal death in developing countries. Their aetiologies are still under investigation. Serum trace elements have been suggested to be involved in the pathogenesis of preeclampsia. Aim of this study was to address the correlation of serum trace elements with preeclampsia and eclampsia. It was a comparative cross-sectional study conducted on conveniently recruited 44 preeclampsia, 33 eclampsia and 27 normotensive pregnant patients. Atomic absorption spectrometry was employed to analyse serum concentrations of Ca, Mg, Cu, Zn and Fe. Data were analysed by Student's t test, one-way analysis of variance and multinomial logistic and binary regression analyses. p < 0.05 was considered as a level of significance. In preeclampsia, the serum Ca and Mg were significantly lower than those in eclampsia, while Cu and Zn values were higher. Significant changes of Ca, Mg and Cu were noted among preeclampsia, eclampsia and pregnant control. Serum Ca and Mg indicated a positive association, and Cu gave a negative association in preeclampsia. Cu/Fe ratio was high in eclampsia. Significant correlations of Mg with Zn in eclampsia and Mg with Fe in preeclampsia and eclampsia were predicted. Significant changes in serum trace element levels were present in preeclampsia and eclampsia that may have a link with the pathogenesis of pregnancy disorder.

Reproductive outcomes and risk of subsequent illness in women diagnosed with postpartum psychosis

OBJECTIVES

Women who experience postpartum psychosis (PP) seek guidance on further pregnancies and risk of illness; however, empirical data are limited. This study describes reproductive and mental health outcomes in women diagnosed with PP and examines clinical risk factors as predictors of further illness.

METHODS

A retrospective cohort design was used; 116 women who experienced episodes of mania or depression with psychotic features within six weeks of childbirth were recruited. All subjects underwent clinical diagnostic interviews and medical case notes were reviewed.

RESULTS

Only 33% of women had an antecedent history, of which 34% had bipolar disorder and 55% unipolar depression. Only 58% of those with PP in their first pregnancy had a subsequent pregnancy, and 18% of marriages ended following the PP episode. Clinical presentation at the time of initial episode did not influence the timing of the onset of symptoms, treatment, or recovery. Although 86% of patients received treatment within 30 days of onset, 26% of women reported ongoing symptoms at a year after delivery. The recurrence rate of PP was 54.4%; a longer duration of the index episode (p < 0.05) and longer latency between the index PP and next pregnancy predicted a subsequent PP. The rate of subsequent non-puerperal episodes was 69%, and all these episodes were bipolar.

CONCLUSIONS

Postpartum psychosis is difficult to predict in women with no antecedent history and is associated with a high rate of subsequent puerperal and non-puerperal illness. Risk of further illness needs to be conveyed in order to allow fully informed decisions to be made regarding future pregnancies.

Why preeclampsia still exists?

Preeclampsia (PE) is a deadly gestational disease affecting up to 10% of women and specific of the human species. Preeclampsia is clearly multifactorial, but the existence of a genetic basis for this disease is now clearly established by the existence of familial cases, epidemiological studies and known predisposing gene polymorphisms. PE is very common despite the fact that Darwinian pressure should have rapidly eliminated or strongly minimized the frequency of predisposing alleles. Consecutive pregnancies with the same partner decrease the risk and severity of PE. Here, we show that, due to this peculiar feature, preeclampsia predisposing-alleles can be differentially maintained according to the familial structure. Thus, we suggest that an optimal frequency of PE-predisposing alleles in human populations can be achieved as a result of a trade-off between benefits of exogamy, importance for maintaining genetic diversity and increase of the fitness owing to a stable paternal investment.

Emerging new biomarkers of preeclampsia

Preeclampsia continues to plague some of the most vulnerable women and fetuses. It is surprisingly prevalent in developing and developed nations. According to the World Health Organization, hypertension during pregnancy is a leading cause of maternal mortality in industrialized countries at 16% and up to 25% in developing countries. As the pathogenesis of this disease is being unraveled, we are afforded new opportunities to develop novel biomarkers for early identification and prevention of disease. The angiogenic markers including soluble fms-like tyrosine kinase 1, placental growth factor, and soluble endoglin have demonstrated to be the most promising, perhaps in conjunction with traditional markers such as plasma protein-13 and uterine artery Doppler studies. There is also increasing evidence that the podocyte is shed during the course of preeclampsia, which may be useful for diagnosis. Systems biology approaches to biomarker discovery such as proteomics and metabolomics are also gaining more attention and will most certainly open new avenues of research. In this review, we present the best studied biomarkers of preeclampsia to date.

Parent-offspring conflict and the persistence of pregnancy-induced hypertension in modern humans

Preeclampsia is a major cause of perinatal mortality and disease affecting 5–10% of all pregnancies worldwide, but its etiology remains poorly understood despite considerable research effort. Parent-offspring conflict theory suggests that such hypertensive disorders of pregnancy may have evolved through the ability of fetal genes to increase maternal blood pressure as this enhances general nutrient supply. However, such mechanisms for inducing hypertension in pregnancy would need to incur sufficient offspring health benefits to compensate for the obvious risks for maternal and fetal health towards the end of pregnancy in order to explain why these disorders have not been removed by natural selection in our hunter-gatherer ancestors. We analyzed >750,000 live births in the Danish National Patient Registry and all registered medical diagnoses for up to 30 years after birth. We show that offspring exposed to pregnancy-induced hypertension (PIH) in trimester 1 had significantly reduced overall later-life disease risks, but increased risks when PIH exposure started or developed as preeclampsia in later trimesters. Similar patterns were found for first-year mortality. These results suggest that early PIH leading to improved postpartum survival and health represents a balanced compromise between the reproductive interests of parents and offspring, whereas later onset of PIH may reflect an unbalanced parent-offspring conflict at the detriment of maternal and offspring health.

Interpregnancy interval and obstetrical complications

Obstetricians are often presented with questions regarding the optimal interpregnancy interval (IPI). Short IPI has been associated with adverse perinatal and maternal outcomes, ranging from preterm birth and low birth weight to neonatal and maternal morbidity and mortality. Long IPI has in turn been associated with increased risk for preeclampsia and labor dystocia. In this review, we discuss the data regarding these associations along with recent studies revealing associations of short IPI with birth defects, schizophrenia, and autism. The optimal IPI may vary for different subgroups. We discuss the consequences of short IPI in women with a prior cesarean section, in particular the increased risk for uterine rupture and the considerations regarding a trial of labor in this subgroup. We review studies examining the interaction between short IPI and advanced maternal age and discuss the risk-benefit assessment for these women. Finally, we turn our attention to women after a stillbirth or an abortion, who often desire to conceive again with minimal delay. We discuss studies speaking in favor of a shorter IPI in this group. The accumulated data allow for the reevaluation of current IPI recommendations and management guidelines for women in general and among subpopulations with special circumstances. In particular, we suggest lowering the current minimal IPI recommendation to only 18 months (vs 24 months according to the latest World Health Organization recommendations), with even shorter recommended minimal IPI for women of advanced age and those who conceive after a spontaneous or induced abortion.

Change in paternity and select perinatal outcomes: causal or confounded?

Select social, behavioural and maternal characteristics were evaluated to determine if they were confounding factors in the association between paternity change and pre-eclampsia, small for gestational age (SGA) and pre-term delivery, in a sample of 1,409 women. Multivariate logistic regression analysis was used to determine if any of these risk factors modified the association between changing paternity and the selected perinatal outcomes. Results of the analysis showed that women who changed partners were more likely to possess potentially confounding risk factors compared with those who had not. Paternity change was 2.75 times more likely to be associated with the development of pre-eclampsia (95% CI 1.33; 5.68) and 2.25 times more likely to be associated with an SGA infant on weight (95% CI 1.13; 4.47), after adjusting for selected risk factors. Paternity change remains a significant risk factor for pre-eclampsia and SGA in the presence of select risk factors.

Regulatory T cells in preeclampsia: some answers, more questions?

This Commentary highlights the article by Hsu et al (in this issue) reporting an enrichment in induced regulatory T cells (iTregs) in normal pregnancy but not in preeclampsia, implicating iTreg defect as central to the pathogenesis of preeclampsia.

Significance of uteroplacental Doppler at midtrimester in patients with favourable obstetric history

OBJECTIVE

To reassess the usefulness of midtrimester uterine Doppler in low-risk multiparous women.

METHODS

We prospectively recruited low-risk pregnant women at 20-22 weeks attending our clinic. Among those, women with a favourable obstetric history (group A) were distinguished from nulliparous (group B) and of each group we measured uterine artery Doppler (pulsatility index (PI)). We evaluated the accuracy of uterine artery Doppler in the prediction of preeclampsia and small for gestational age (SGA) neonates.

RESULTS

Between January 2009 and October 2010, 382 women were included in the study of which 147 in group A and 235 in group B. Overall, 26/382 (6.8%) women presented preeclampsia and SGA occurred in 59/382 (15.4%) cases. In our population, at a 10% false positive rate (FPR) uterine artery Doppler showed a detection rate (DR) of 19.2% for preeclampsia and of 37.3% for SGA, with a higher sensitivity for SGA neonates delivered ≤ vs. >34 weeks (87% vs. 29.4%). The univariable receiver operating characteristics (ROC) curve by uterine artery PI yielded a significant prediction only for SGA in nulliparous women (areas under the curve (AUC) of 0.70; 95% CI 0.60-0.79).

CONCLUSIONS

Our data confirmed that midtrimester uterine artery Doppler is not an efficient strategy in anticipating the risk of pregnancy complications among low-risk multiparous women.

The role of androgens and the androgen receptor in cycling endometrium

Androgens and the androgen receptor (AR) are not only required for male reproductive function, they are also essential for female reproductive physiology. Widely expressed in female reproductive tissues, AR levels fluctuate in a regulated manner in the cycling endometrium. Female androgen production depends on the adrenal glands and expression of key enzymes in the endometrium that facilitate local androgen biosynthesis and conversion. Moreover, levels of circulating androgens, in women of reproductive age, fluctuate in a cycle-dependent manner and a mid-cycle peak is associated with conception. AR and androgen signalling have a decisive role in the differentiation of human endometrial stromal cells into decidual cells. Compelling evidence for androgen signalling in the regulation of endometrial function pertaining to implantation and pregnancy is provided by epidemiological studies demonstrating a strong association between polycystic ovary syndrome, premature ovarian failure or advanced maternal age and adverse pregnancy outcome. Thus, androgen signalling is an essential component of normal endometrial physiology and its perturbation is associated with reproductive failure.

Early detection of maternal risk for preeclampsia

Preeclampsia is one of the leading causes of maternal and fetal morbidity and mortality. New molecular insights offer new possibilities of early diagnosis of elevated maternal risk. Maternal risk factors, biophysical parameters like Doppler examination of the uterine arteries and biochemical parameters allow early risk calculation. Preventive and effective therapeutic agents like acetylsalicylacid can be started in the early second trimester. This article reviews the diagnostic possibilities of early risk calculation to detect women having high risk for preeclampsia and the potential benefits for them, the offspring and health care systems. We provide risk calculation for preeclampsia as an important and sensible part of first trimester screening.

The pathophysiology of preeclampsia in view of the two-stage model

Preeclampsia is a common and severe disease in pregnancy, a major cause of maternal and fetal morbidity and mortality. The main features of the disease are de novo hypertension after the 20th gestational week and proteinuria, and it is frequently accompanied by edema and other subjective symptoms. The origin of the disease is the placenta, but its sequelae affect multiple organ systems. According to the two-stage model of preeclampsia, the abnormal and hypoperfused placenta (stage 1) releases factors to the bloodstream, which are responsible for the maternal symptoms (stage 2). Oxidative stress, impaired function of nitric-oxide synthase, cellular and humoral immunological factors play an important role in the pathophysiology of the placenta. Endothelial dysfunction is the common denominator of the clinical symptoms. The theory explains the origins of hypertension, proteinuria, edema and other symptoms as well. Orv. Hetil., 2012, 153, 1167–1176.

FOLATE METABOLISM AND PREECLAMPSIA

Preeclampsia (PE) is a multisystem disorder of human pregnancy, affecting about 6% of all pregnancies worldwide, and is one of the leading causes of maternal and infant morbidity and mortality. Despite decades of research into the pathogenesis of this complex disease, the underlying mechanisms remain unclear. As a result, the options for prevention and management of PE are limited. In recent years, there has been a growing body of evidence suggesting that folate deficiency is associated with PE, and folic acid supplementation may reduce the risk of developing PE in certain populations. Folate contributes to cell division and growth, and folate metabolism is involved in a large number of physiological and pathophysiological processes in human development. Sufficient supply of folate is therefore particularly important during pregnancy. Nevertheless, the exact mechanisms of folic acid deficiency increasing the risk of developing PE are still unclear. This article reviews what is understood about the aetiology of PE and the relationship between folate metabolism and PE so as to enhance further discussions on the subject.

Secular trends in the epidemiology of pre-eclampsia throughout 40 years in Norway: prevalence, risk factors and perinatal survival

Pre-eclampsia is a leading complication of pregnancy, associated with maternal and neonatal morbidity. The present study describes the epidemiology of pre-eclampsia in Norway, with data from the Medical Birth Registry of Norway, covering 40 years. We aimed at describing time trends in prevalence, selected risk factors and perinatal mortality. We also analysed time trends in recurrence risk of total pre-eclampsia and pre-eclampsia with preterm delivery. A total of 2,416,501 women giving birth during 1967-2008 were included. Prevalence of pre-eclampsia increased from 1967 to 1999 and decreased thereafter, with an overall prevalence of 3%. Rates increased more over time among younger than older women, resulting in a significantly lower excess risk of pre-eclampsia associated with high maternal age in later years. For example, relative risk (RR) of pre-eclampsia among primiparae aged ≥35 relative to <25 years changed from 2.4 [95% confidence interval (CI) 2.1, 2.7] in 1967-1976 to 1.2 [95% CI 1.1, 1.3] in 1999-2008. For recurrence risk, subsequent pregnancies to a mother were linked, with the mother being the unit of analysis. Recurrence risk of pre-eclampsia was high, particularly recurrence of preterm pre-eclampsia, with overall RR close to 50 of a second pregnancy with pre-eclampsia and preterm birth compared with women without pre-eclampsia in first pregnancies. Finally, stillbirth associated with pre-eclampsia decreased more than neonatal mortality over time, and in the last 5 years only a moderate excess risk of stillbirth and neonatal death was observed.

Interpregnancy change in smoking habits and risk of preeclampsia: a population-based study

BACKGROUND

Maternal smoking has been associated with decreased risk of preeclampsia; however, it is uncertain whether this association is causal. An argument for causality would be strengthened if changes in smoking status across consecutive pregnancies were related to the risk of preeclampsia.

METHODS

We used data from the National Swedish Birth Register to ascertain the associations between changes in smoking status during the first two successive pregnancies and risk of preeclampsia in the second pregnancy in 371,627 women between 1992 and 2006. Multivariable logistic regression models were used to estimate adjusted odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Compared to women who did not smoke in either pregnancy, the risk of preeclampsia was reduced in women who smoked in both pregnancies (adjusted OR = 0.54; 95% CI = 0.47, 0.63), in those who only smoked in second pregnancy (OR = 0.76; 95% CI = 0.58, 0.99) and, to a lesser extent, in women who smoked only in the first pregnancy (OR = 0.81; 95% CI = 0.70, 0.94). History of preeclampsia in the first pregnancy did not substantially modify these associations.

CONCLUSION

These data add support to a causal interpretation of the observed inverse association between smoking during pregnancy and risk of preeclampsia.