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

Pregnancy-Associated Maternal Mortality Within One Year After Childbirth: Population-Based Cohort Study

OBJECTIVE

The objective of this study is to assess associations between pregnancy complications and pregnancy-associated maternal mortality (PAM) within 1 year after childbirth.

DESIGN

Population-based cohort study.

SETTING

Norway, 1967-2020.

POPULATION

1 237 254 mothers with one or more singleton pregnancies registered in the Medical Birth Registry, 1967-2019 and followed in the Cause of Death Registry to 2020.

METHODS

Logistic regression was used to calculate odds ratios (ORs) with 95% confidence intervals (CIs), adjusted for maternal education, age, year of first childbirth and chronic medical conditions.

MAIN OUTCOME MEASURES

PAM by lifetime history of pregnancy complications: placental abruption, preeclampsia, preterm birth, perinatal death, small for gestational age (< 2.5 percentile), gestational diabetes and gestational hypertension.

RESULTS

Crude OR for PAM was 4.24 (95% CI 3.53-5.10), if complications occurred in the last pregnancy, whereas 2.52 (2.08-3.06) if complications occurred in the first pregnancy, compared to mothers without complications in any pregnancy. Adjusted ORs for PAM when complications occurred in the last pregnancy were, for placental abruption 3.75 (1.20-11.72), preeclampsia: 4.42 (3.17-6.15), preterm birth: 4.32 (3.25-5.75), perinatal death: 24.18 (16.66-35.08), small for gestational age: 2.90 (1.85-4.54), gestational diabetes: 1.43 (0.63-3.25) and pregnancy hypertension: 2.05 (1.12-3.74) compared to mothers without complications. The OR for PAM increased slightly by increasing the number of complicated pregnancies but the trend was stronger for increasing number of complications in the last pregnancy (e.g., during 1999-2019: one complication; 4.14 [2.79-6.13], two complications; 11.50 [6.81-19.43]).

CONCLUSION

Complications in the last pregnancy were more strongly associated with PAM than those in the first pregnancy.

Risk of adverse pregnancy outcomes in twin- and singleton-born women: An inter-generational cohort study

OBJECTIVE

To compare the risk of adverse pregnancy outcomes between twin-born and singleton-born women. We also evaluated whether in utero exposure to pre-eclampsia or preterm delivery affected adverse pregnancy outcomes in women's own pregnancies.

DESIGN

Population-based cohort study.

SETTING

Medical Birth Registry of Norway 1967-2020.

POPULATION

9184 twin-born and 492 894 singleton-born women during 1967-2005, with their later pregnancies registered during 1981-2020.

METHODS

Data from an individual's birth were linked to their later pregnancies. We used generalised linear models with log link binomial distribution to obtain exponentiated regression coefficients that estimated relative risks (RRs) with 95% confidence intervals (CIs) for associations between twin- or singleton-born women and later adverse pregnancy outcomes.

MAIN OUTCOME MEASURES

Pre-eclampsia, preterm delivery or perinatal loss in twin-born compared with singleton-born women.

RESULTS

There was no increased risk for adverse outcomes in twin-born compared with singleton-born women: adjusted RRs for pre-eclampsia were 1.00 (95% CI 0.93-1.09), for preterm delivery 0.96 (95% CI 0.90-1.02) and for perinatal loss 1.00 (95% CI 0.84-1.18). Compared with singleton-born women exposed to pre-eclampsia in utero, twin-born women exposed to pre-eclampsia had lower risk of adverse outcomes in their own pregnancies; the aRR for pre-eclampsia was 0.73 (95% CI 0.58-0.91) and for preterm delivery was 0.71 (95% CI 0.56-0.90). Compared with preterm singleton-born women, preterm twin-born women did not differ in terms of risk of pre-eclampsia (aRR 1.05, 95% CI 0.92-1.21) or perinatal loss (aRR 0.99, 95% CI 0.71-1.37) and had reduced risk of preterm delivery (RR 0.83, 95% CI 0.74-0.94).

CONCLUSIONS

Twin-born women did not differ from singleton-born women in terms of risk of adverse pregnancy outcomes. Twin-born women exposed to pre-eclampsia in utero, had a lower risk of pre-eclampsia and preterm delivery compared with singleton-born women exposed to pre-eclampsia.

Heterogeneity in the risk of cardiovascular disease mortality after the hypertensive disorders of pregnancy across mothers' lifetime reproductive history

BACKGROUND

Prior studies on maternal cardiovascular disease (CVD) mortality and hypertensive disorders of pregnancy (HDP) have focused only on a woman's first birth and have not accounted for successive affected pregnancies.

OBJECTIVES

The objective of this study is to identify mothers' risk of CVD mortality considering lifetime reproductive history.

METHODS

We used data from the Medical Birth Registry of Norway, the Norwegian Cause of Death Registry, and the Norwegian National Population Register to identify all mothers who gave birth from 1967 to 2020. Our outcome was mothers' CVD death before age 70. The primary exposure was the lifetime history of HDP. The secondary exposure was the order of HDP and gestational age at delivery of pregnancies with HDP. We used Cox regression models to estimate hazard ratio (HR) and 95% confidence interval (CI), adjusting for education, mother's age, and year of last birth. These models were stratified by the lifetime number of births.

RESULTS

Among 987,378 mothers, 86,294 had HDP in at least one birth. The highest CVD mortality, relative to mothers without HDP, was among those with a pre-term HDP in their first two births, although this represented 1.0% of mothers with HDP (HR 5.12, 95% CI 2.66, 9.86). Multiparous mothers with term HDP in their first birth only had no increased risk of CVD relative to mothers without HDP (36.9% of all mothers with HDP; HR 1.12, 95% CI 0.95, 1.32). All other mothers with HDP had a 1.5- to 4-fold increased risk of CVD mortality.

CONCLUSIONS

This study identified heterogeneity in the risk of CVD mortality among mothers with a history of HDP. A third of these mothers are not at higher risk compared to women without HDP, while some less common patterns of HDP history are associated with severe risk of CVD mortality.

Postpartum follow-up of women with preeclampsia: facilitators and barriers - A qualitative study

BACKGROUND

Pregnancy causes physiological changes to the maternal organ systems that can be regarded as a cardiometabolic stress test for women. Preeclampsia, a pregnancy complication characterized by new onset of hypertension in combination with proteinuria or end-organ dysfunction, affects approximately 2-8% of pregnancies. Adverse pregnancy outcomes, including preeclampsia, have been described as a failed stress test and have been consistently linked with increased risk of cardiovascular disease later in life. The postpartum period is therefore often regarded as a window of opportunity for cardiovascular disease prevention. However, we lack knowledge about how women with preeclampsia experience current postpartum care in the Norwegian health system. The aim of this qualitative study is to uncover women's perspectives and preferences regarding postpartum follow-up.

METHODS

Semi-structured telephone interviews were conducted with 17 women following a six-month lifestyle intervention study. Participants were 9-20 months postpartum, following a pregnancy complicated by preeclampsia. Data were analyzed using Malterud's systematic text condensation.

RESULTS

We identified five themes, each with 2-3 subthemes, that demonstrate how women with recent preeclampsia experience postpartum follow-up: (1) fear and uncertainty (a body out of balance and facing an uncertain future), (2) a conversation on lifestyle - not really that difficult (preeclampsia as a gateway, a respectful approach, and a desire for more constructive feedback), (3) when your own health is not a priority (a new everyday life, out of focus, and lack of support), (4) motivation for lifestyle changes (an eye opener, lack of intrinsic motivation, and a helping hand), and (5) lack of structured and organized follow-up (there should be a proper system, a one-sided follow-up care, and individual variation in follow-up care).

CONCLUSIONS

Findings from this study highlight the need for more systematic postpartum follow-up for women after a pregnancy complicated by preeclampsia. Further research is required to explore the potential use of standardized guidelines and routine invitations to postpartum care. Furthermore, exploring health care professionals' experiences is crucial to ensure their engagement in postpartum care after complicated pregnancies.

Fetal Exposure to Preeclampsia and Later Risk of Cardiometabolic Disorders: A Population-Based Cohort Study

BACKGROUND

Fetal preeclampsia exposure has been associated with later cardiometabolic disease. However, this association has been investigated in few large population-wide studies, and it is unknown whether the association represents a causal relationship or is the result of shared etiological factors.

METHODS

To further investigate the relationship between preeclampsia exposure and later cardiometabolic disease, we identified 1 692 944 singleton infants born in Norway during 1967 to 1997, where 44 299 were exposed to preeclampsia in utero. The individuals were followed for hypertension, diabetes, and dyslipidemia as defined by dispensed medication. We used Cox regression models to calculate the association between preeclampsia exposure and cardiometabolic outcomes adjusting for measured confounders. We also used full sibling comparisons and stratified Cox regression to control for unmeasured familial confounders.

RESULTS

On the population level, exposed individuals had increased risk of hypertension (adjusted hazard ratio [aHR] 1.51 [95% CI, 1.41-1.63]), diabetes (aHR 1.33 [95% CI, 1.24-1.43], and dyslipidemia (aHR 1.28 [95% CI, 1.13-1.45]) compared with unexposed individuals. In sibling data, individuals not exposed to preeclampsia, but with an exposed sibling, had higher risk of hypertension and diabetes than individuals where no siblings were exposed to preeclampsia. Moreover, when comparing siblings discordant on preeclampsia exposure, there were no associations between preeclampsia and hypertension (aHR 1.05 [95% CI, 0.88-1.26]), diabetes (aHR 0.96 [95% CI, 0.80-1.14]), and dyslipidemia (aHR 0.86 [95% CI, 0.62-1.20]).

CONCLUSIONS

Fetal preeclampsia exposure was associated with adult life hypertension, diabetes, and dyslipidemia, but these associations were likely due to shared etiological factors, rather than exposure to the preeclamptic condition itself.

Prevalence of preeclampsia and algorithm of adverse foeto-maternal risk factors among pregnant women in the Central Region of Ghana: A multicentre prospective cross-sectional study

BACKGROUND

Preeclampsia is a leading cause of foeto-maternal deaths especially in Sub-Saharan Africa. However, the prevalence and risk factors of preeclampsia are scarce in the Central region of Ghana with previous study assessing individual independent risk factors. This study determined the prevalence and algorithm of adverse foeto-maternal risk factors of preeclampsia.

METHODS

This multi-centre prospective cross-sectional study was conducted from October 2021 to October 2022 at the Mercy Women's Catholic Hospital and Fynba Health Centre in Central region, Ghana. A total of 1,259 pregnant women were randomly sampled and their sociodemographic, clinical history, obstetrics and labour outcomes were recorded. Logistic regression analysis using SPSS version 26 was performed to identify risk factors of preeclampsia.

RESULTS

Of the 1,259 pregnant women, 1174 were finally included in the study. The prevalence of preeclampsia was 8.8% (103/1174). Preeclampsia was common among 20-29 years age group, those who had completed basic education, had informal occupation, multigravida and multiparous. Being primigravida [aOR = 1.95, 95% CI (1.03-3.71), p = 0.042], having previous history of caesarean section [aOR = 4.48, 95% CI (2.89-6.93), p<0.001], foetal growth restriction [aOR = 3.42, 95% CI (1.72-6.77), p<0.001] and birth asphyxia [aOR = 27.14, 95% CI (1.80-409.83), p = 0.017] were the independent risk factors of preeclampsia. Pregnant women exhibiting a combination of primigravida, previous caesarean section and foetal growth restriction were the highest risk for preeclampsia [aOR = 39.42, 95% CI (8.88-175.07, p<0.001] compared to having either two or one of these factors.

CONCLUSION

Preeclampsia is increasing among pregnant women in the Central region of Ghana. Pregnant women being primigravida with foetal growth restriction and previous history of caesarean section are the highest risk population likely to develop preeclampsia with neonates more likely to suffer adverse birth outcome such as birth asphyxia. Targeted preventive measures of preeclampsia should be created for pregnant women co-existing with multiple risk factors.

Fetal sex and risk of preeclampsia: Dose maternal race matter?

OBJECTIVE

To examine whether maternal race could affect the relationship between fetal sex and preeclampsia.

MATERIAL AND METHODS

This study was a cohort analysis using prospectively collected data from pregnant women who participated in the Vitamin Antenatal Asthma Reduction Trial (VDAART). Preeclampsia was the secondary outcome of VDAART. We examined the association of fetal sex with preeclampsia and its potential interaction with maternal race in 813 pregnant women (8% with preeclampsia) in logistic regression models with adjustment for preterm birth (<37 weeks of gestation), maternal age, education, and body mass index at enrollment and clinical center. We further conducted a race stratified analysis and also examined whether any observed association was dependent on the gestational age at delivery and prematurity.

RESULTS

In an analysis of all races combined, preeclampsia was not more common among pregnant women with a male fetus compared to those with a female fetus (odds ratio [OR] = 1.3, 95% CI = 0.81, 2.24). There was an interaction between African American race and fetal sex in association with preeclampsia after adjustment for preterm delivery and other potential confounders (p = .014). In race stratified analyses, we observed higher odds of preeclampsia among African American pregnant women who carried male fetuses after adjustment for preterm delivery and other potential confounders (adjusted OR = 2.4, 95% CI = 1.12, 5.60).

CONCLUSION

We observed fetal sexual dimorphic differences in the occurrence of preeclampsia in African American women, but not in Whites. Information on fetal sex may ultimately improve the prediction of pre-eclampsia in African American mothers, who might be at higher risk for this adverse condition in pregnancy.

Recording of Chronic Diseases and Adverse Obstetric Outcomes during Hospitalizations for a Delivery in the National Swiss Hospital Medical Statistics Dataset between 2012 and 2018: An Observational Cross-Sectional Study

The prevalence of chronic diseases during pregnancy and adverse maternal obstetric outcomes in Switzerland has been insufficiently studied. Data sources, which reliably capture these events, are scarce. We conducted a nationwide observational cross-sectional study (2012−2018) using data from the Swiss Hospital Medical Statistics (MS) dataset. To quantify the recording of chronic diseases and adverse maternal obstetric outcomes during delivery in hospitals or birthing centers (delivery hospitalization), we identified women who delivered a singleton live-born infant. We quantified the prevalence of 23 maternal chronic diseases (ICD-10-GM) and compared results to a nationwide Danish registry study. We further quantified the prevalence of adverse maternal obstetric outcomes (ICD-10-GM/CHOP) during the delivery hospitalization and compared the results to existing literature from Western Europe. We identified 577,220 delivery hospitalizations, of which 4.99% had a record for ≥1 diagnosis of a chronic disease (versus 15.49% in Denmark). Moreover, 13 of 23 chronic diseases seemed to be substantially under-recorded (8 of those were >10-fold more frequent in the Danish study). The prevalence of three of the chronic diseases was similar in the two studies. The prevalence of adverse maternal obstetric outcomes was comparable to other European countries. Our results suggest that chronic diseases are under-recorded during delivery hospitalizations in the MS dataset, which may be due to specific coding guidelines and aspects regarding whether a disease generates billable effort for a hospital. Adverse maternal obstetric outcomes seemed to be more completely captured.

Immunity at maternal-fetal interface: KIR/HLA (Allo)recognition

Both KIR and HLA are the most variable gene families in the human genome. The recognition of the semi-allogeneic embryo-derived trophoblasts by maternal decidual NK (dNK) cells is essential for the establishment of the functional placenta. This recognition is based on the KIR-HLA interactions and trophoblast expresses a specific HLA profile that constitutes classical polymorphic HLA-C and non-classical oligomorphic HLA-E, HLA-F, and HLA-G molecules. This review highlights some features of the KIR/HLA-C (allo)recognition by decidual NK (dNK) cells as a main immune cell population specifically enriched at maternal-fetal interface during human early pregnancy. How KIR/HLA-C axis operates in pregnancy disorders and in the context of transplacental infections is discussed as well. We summarized old and new data on dNK-cell functional plasticity, their selective expression of KIR and fetal maternal/paternal HLA-C haplotypes present. Results showed that KIR-HLA-C combinations and the corresponding axis operate differently in each pregnancy, determined by the variability of both maternal KIR haplotypes and fetus' maternal/paternal HLA-C allotype combinations. Moreover, the maturation of NK cells strongly depends on if or not HLA allotypes for certain KIR are present. We suggest that the unique KIR/HLA combinations reached in each pregnancy (normal and pathological) should be studied according to well-defined guidelines and unified methodologies to have comparable results ease to interpret and use in clinics.

Cesarean delivery in Norwegian nulliparous women with singleton cephalic term births, 1967-2020: a population-based study

Background

Nulliparous women contribute to increasing cesarean delivery in the Nordic countries and advanced maternal age has been suggested as responsible for rise in cesarean delivery rates in many developed countries. The aim was to describe changes in cesarean delivery rates among nulliparous women with singleton, cephalic, term births by change in sociodemographic factors across 50 years in Norway.

Methods

We used data from the Medical Birth Registry of Norway and included 1 067 356 women delivering their first, singleton, cephalic, term birth between 1967 and 2020. Cesarean delivery was described by maternal age (5-year groups), onset of labor (spontaneous, induced and pre-labor CD), and time periods: 1967–1982, 1983–1998 and 1999–2020. We combined women’s age, onset of labor and time period into a compound variable, using women of 20–24 years, with spontaneous labor onset during 1967–1982 as reference. Multivariable regression models were used to estimate adjusted relative risk (ARR) of cesarean delivery with 95% confidence interval (CI).

Results

Overall cesarean delivery increased both in women with and without spontaneous onset of labor, with a slight decline in recent years. The increase was mainly found among women < 35 years while it was stable or decreased in women >  = 35 years. In women with spontaneous onset of labor, the ARR of CD in women >  = 40 years decreased from 14.2 (95% CI 12.4–16.3) in 1967–82 to 6.7 (95% CI 6.2–7.4) in 1999–2020 and from 7.0 (95% CI 6.4–7.8) to 5.0 (95% CI 4.7–5.2) in women aged 35–39 years, compared to the reference population. Despite the rise in induced onset of labor over time, the ARR of CD declined in induced women >  = 40 years from 17.6 (95% CI 14.4–21.4) to 13.4 (95% CI 12.5–14.3) while it was stable in women 35–39 years.

Conclusion

Despite growing number of Norwegian women having their first birth at a higher age, the increase in cesarean delivery was found among women < 35 years, while it was stable or decreased in older women. The increase in cesarean delivery cannot be solely explained by the shift to an older population of first-time mothers.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04755-3.

Substantial decrease in preeclampsia prevalence and risk over two decades: A population-based study of 1,153,227 deliveries in Norway

OBJECTIVES

Analyze secular trends of preeclampsia in Norway based on risk factors.

STUDY DESIGN

Population-based cohort study of 1,153,227 women using data from Medical Birth Registry of Norway from 1999 to 2018. Aggregated data from Norwegian Prescription Database from 2004 to 2018 were used. Main exposure variable was time period. Descriptive statistics identified the prevalence of preeclampsia, labor induction and aspirin use. Multiple logistic regression analysis was performed to estimate the risk of preeclampsia during the time periods.

MAIN OUTCOME MEASURES

Preeclampsia.

RESULTS

Overall preeclampsia prevalence decreased from 4.3% in 1999-2002 to 2.7% in 2015-2018. A reduction was observed in all subgroups of women with known risk factors (age, nulliparity, diabetes, chronic hypertension, assisted reproduction, twin pregnancy). Adjusted risk of preeclampsia was reduced by 44% from 1999-2002 to 2015-2018 (aOR = 0.56, 95%CI 0.54, 0.58), while the net prevalence of gestational hypertension remained stable over the study period. Labor induction increased 104%. Aspirin prescriptions increased among fertile women in the general Norwegian population.

CONCLUSIONS

Preeclampsia prevalence and risk were reduced regardless of risk factors and despite an increased proportion of high-risk parturients (advanced age, lower parity, use of assisted reproduction). A corresponding increase in aspirin prescriptions among fertile women and an overall increase in labor inductions were also observed, suggesting that clinical interventions may partly explain the observed reduction in preeclampsia prevalence. Lower average blood pressure and improved health in the population may also explain some of the reduction.

Association of family history with incidence and gestational hypertension outcomes of preeclampsia

Background

Gestational hypertension and preeclampsia are hypertensive disorders related to pregnancy that can cause maternal morbidity and fetal growth retardation. The association of these disorders with family history remains unclear.

Objectives

To examine the degree of family aggregation of preeclampsia and gestational hypertension in Taiwan.

Methods

The study was conducted using the data from the National Health Insurance Database of Taiwan. Delivery events in Taiwan from 1999 to 2013 were collected. Preeclampsia was identified based on the hospital diagnosis of index delivery. The family aggregation pattern of preeclampsia was assessed and analyzed using the relationship registered in the database with the patients.

Results

A total of 60,314 preeclampsia events were identified among 4,091,641 deliveries, accounting for 1.5% of the cohort. The incidence of preeclampsia increased with maternal age. A total of 768 preeclampsia events occurred in mothers who had a sororal history of preeclampsia (n = 20,704), accounting for 1.3% of all preeclampsia events (n = 60,314). Mothers who had a sororal history of preeclampsia had a relative risk (RR) of 2.6 (95% confidence interval [CI]: 2.41-2.80) for preeclampsia compared with mothers who did not have a sororal history of preeclampsia. The RR for gestational hypertension was 2.79 (95% CI: 2.36-3.3) in mothers with a positive sororal history of gestational hypertension.

Conclusions

Having a sororal history of preeclampsia was a strong risk factor for preeclampsia and gestational hypertension in mothers in Taiwan. The pattern of family aggregation was similar at all maternal ages.

Clustering Longitudinal Blood Pressure Trajectories to Examine Heterogeneity in Outcomes Among Preeclampsia Cases and Controls

[Figure: see text].

Cardiovascular Health After Preeclampsia: Patient and Provider Perspective

Background: Preeclampsia predicts future cardiovascular disease (CVD) yet few programs exist for post-preeclampsia care. Methods: The Health after Preeclampsia Patient and Provider Engagement Network workshop was convened at the Radcliffe Institute for Advanced Study in June 2018. The workshop sought to identify: 1) patient perspectives on barriers and facilitators to CVD risk reduction; 2) clinical programs specialized in post-preeclampsia care; 3) recommendations by national organizations for risk reduction; and 4) next steps. Stakeholders included the Preeclampsia Foundation, patients, clinicians who had initiated CVD risk reduction programs for women with prior preeclampsia, researchers, and national task force members. Results: Participants agreed there is insufficient awareness and action to prevent CVD after preeclampsia. Patients suggested a clinician checklist to ensure communication of CVD risks, enhanced training for clinicians on the link between preeclampsia and CVD, and a post-delivery appointment with a clinician knowledgeable about this link. Clinical programs primarily served patients in the first postpartum year, bridging obstetrical and primary care. They recommended CVD risk modification with periodic blood pressure, weight, lipid and diabetes screening. Barriers included the paucity of programs designed for this population and gaps in insurance coverage after delivery. The American Heart Association, the American College of Obstetricians and Gynecologists, and the Preeclampsia Foundation have developed guidelines and materials for patients and providers to guide management of women with prior preeclampsia. Conclusions: Integrated efforts of patients, caregivers, researchers, and national organizations are needed to improve CVD prevention after preeclampsia. This meeting's recommendations can serve as a resource and catalyst for this effort.

Pregnancy in Patients With AQP4-Ab, MOG-Ab, or Double-Negative Neuromyelitis Optica Disorder

OBJECTIVE

To analyze the effects of pregnancy on neuromyelitis optica spectrum disorder (NMOSD) according to patients' serostatus and immunosuppressive therapy (IST).

METHODS

We performed a retrospective multicenter international study on patients with NMOSD. Patients were tested for aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) antibodies (Ab). Informative pregnancies were reported when NMOSD onset occurred before or during pregnancy or up to 12 months postpartum. The mean annualized relapse rate (ARR) was calculated for the 12 months before conception, for each trimester of pregnancy, and postpartum. Events such as miscarriage, abortion, and preeclampsia were reported. IST was considered if taken in the 3 months before or during pregnancy.

RESULTS

We included 89 pregnancies (46 with AQP4-Ab, 30 with MOG-Ab, and 13 without either Ab) in 58 patients with NMOSD. Compared to the prepregnancy period, the ARR was lower during pregnancy in each serostatus group and higher during the postpartum period in patients with AQP4-Ab (p < 0.01). Forty-eight percent (n = 31) of pregnancies occurred during IST and these patients presented fewer relapses during pregnancy and the 12 months postpartum than untreated patients (26% vs 53%, p = 0.04). Miscarriages occurred in 10 (11%) pregnancies, and were mainly in patients with AQP4-Ab (with or without IST) and a previous history of miscarriage. Preeclampsia was reported in 2 (2%) patients who were AQP4-Ab-positive.

CONCLUSION

We found a rebound in the ARR during the first postpartum trimester that was higher than the prepregnancy period only in AQP4-Ab-positive patients. Taking IST just before or during pregnancy reduces the risk of relapses in these conditions.

Prevalence of hypertensive disorders in pregnancy in China: A systematic review and meta-analysis

Hypertensive disorders in pregnancy (HDP) are associated with various maternal and fetal adverse outcomes and become an increasingly significant threat to Chinese pregnant women. Yet, the prevalence of HDP in China is not clear. We conducted this meta-analysis to estimate the prevalence of HDP and specific subtypes in China. We searched PubMed, Embase, Web of Science, CNKI, Wangfang, and CMB for studies on prevalence of HDP and specific subtypes, published from 1990 to Jan 21, 2020, without language restrictions. We included all studies reported the prevalence of HDP and specific subtypes in Chinese pregnant women. We excluded qualitative studies, case reports, reviews, conference presentations, and studies only provided abstracts. We using a standard self-developed form to extract information from eligible studies. We did meta-analyses by random-effect models and estimated the pooled prevalence of HDP and specific subtypes. In order to explore potential sources of heterogeneity and subgroup effects, we did and meta-regression and subgroup analyses by pre-specified covariates. This study is registered with PROSPERO, number CRD42020166001. We initially identified 4179 records, of which 92 studies with 1,377,448 participants were eligible in the final systematic review and meta-analyses. The pooled prevalence (95% CI) of HDP, gestational hypertension, preeclampsia, mild preeclampsia, severe preeclampsia, eclampsia, chronic hypertension, and chronic hypertension with superimposed preeclampsia were 7.30% (6.60%-8.00%), 3.30% (2.90%-3.70%), 4.50% (4.00%-5.00%), 2.00% (1.70%-2.30%), 2.60% (2.10%-3.00%), 0.11% (0.08%-0.15%), 0.60% (0.30%-0.90%), and 0.60% (0.40%-0.80%), respectively. No publication bias was identified, although heterogeneity was high (I² statistics: 92.0%-99.3%). High prevalence of HDP and the subtypes frequently reported in Western and Northern China. Pregnant women who were aged 35 years and above had high prevalence of HDP and subtypes; women who were overweight or obese had high prevalence of HDP, gestational hypertension and preeclampsia. The prevalence of HDP and the subtypes vary in different areas in China. Given to increasingly prevalent of the risk factors, such as overweight, obesity, and advance maternal age, strategies to prevent and manage HDP need to be improved, especially for women living in Western and Northern China.

Does caesarean delivery in the first pregnancy increase the risk for adverse outcome in the second? A registry-based cohort study on first and second singleton births in Norway

OBJECTIVE

To explore if newborns in the second pregnancy following a previous caesarean delivery (CD) have higher risk of perinatal mortality or cerebral palsy than newborns in pregnancies following a previous vaginal delivery (VD).

DESIGN

Cohort study with information from the Medical Birth Registry of Norway and the Cerebral Palsy Registry of Norway.

SETTING

Births in Norway.

PARTICIPANTS

294 598 women with their first and second singleton delivery during 1996-2015.

MAIN OUTCOME MEASURES

Stillbirth, perinatal mortality, neonatal mortality and cerebral palsy.

RESULTS

Among 294 598 included women, 42 962 (15%) had a CD in their first pregnancy while 251 636 (85%) had a VD. Compared with the second delivery of mothers with a previous VD, the adjusted OR (adjOR), for stillbirth in the second pregnancy following a previous CD was 1.45, 95% CI 1.22 to 1.73; for perinatal death the adjOR was 1.42 (1.22 to 1.73) and for neonatal death 1.13 (0.86 to 1.49). Among children who survived the neonatal period, the adjOR for cerebral palsy was 1.27 (0.99 to 1.64). Secondary outcomes, including small for gestational age, preterm and very preterm birth, uterine rupture and placental complications (eg, postpartum haemorrhage and pre-eclampsia) were more frequent in the subsequent pregnancy following a previous CD compared with a previous VD, in particular for uterine rupture adjOR 86.7 (48.2 to 156.1). Adjustment for potential confounders attenuated the ORs somewhat, but the excess risk in the second pregnancy persisted for all outcomes.

CONCLUSION

A previous CD was in this study associated with increased risk for stillbirth and perinatal death compared with a previous VD. Although less robust, we also found that a previous CD was associated with a slightly increased risk of cerebral palsy among children surviving the neonatal period. The aetiology behind these associations needs further investigation.

Stumped by the Hump: The Curious Rise and Fall of Norwegian Birthweights, 1991-2007

BACKGROUND

There was a distinct rise in mean birthweights in Norway starting in 1991 that plateaued in 1996-2002 and then declined to previous levels. We investigated whether these changes corresponded to trends in neonatal mortality or other birthweight-associated pregnancy outcomes. We also explored known predictors of birthweight and examined whether these could explain the birthweight trends.

METHODS

We calculated mean birthweight for all live births in Norway in each year from 1982 to 2016, together with annual neonatal mortality and proportion of infants born preterm, or with low Apgar score. We stratified mean birthweight over time by factors including parity, gestational age, and Scandinavian versus non-Scandinavian origin of mother, to test robustness of the pattern. In addition, we used multivariable linear regression to obtain adjusted estimates for mean birthweight per year.

RESULTS

A 50-g rise and fall of mean birthweights during a 25-year period was not accompanied by corresponding changes in neonatal mortality, preterm births, or Apgar scores. The distinct hump pattern was restricted to term births and was not apparent among infants of mothers born outside Scandinavia. We saw a similar pattern for Sweden but not Finland. Known predictors of birthweight (such as parity, mode of onset of delivery, and marital status) did not explain the hump.

CONCLUSIONS

A distinct temporal hump in mean birthweight among Norwegian term births had no obvious explanations. Furthermore, these fluctuations in birthweight were not associated indirectly with adverse outcomes in measures of infant health.

TLR3 expression by maternal and fetal cells at the maternal-fetal interface in normal and preeclamptic pregnancies

Inflammation and oxidative stress at the maternal-fetal interface characterize the placental dysfunction that underlies the pregnancy disorder preeclampsia. Specialized fetal trophoblasts directly interact with leukocytes at both sites of the maternal-fetal interface; the uterine wall decidua; and the placenta. TLR3 has been implicated in the harmful inflammation at the maternal-fetal interface in preeclampsia, but the cellular involvement in the decidua and placenta has not been determined. This study aimed to characterize and quantify cell-specific TLR3 expression and function at the maternal-fetal interface in normal and preeclamptic pregnancies. TLR3 expression was assessed by immunohistochemistry and quantified by a novel image-based and cell-specific quantitation method. TLR3 was expressed at the maternal-fetal interface by all decidual and placental trophoblast types and by maternal and fetal leukocytes. Placental, but not decidual, TLR3 expression was significantly higher in preeclampsia compared to normal pregnancies. This increase was attributed to placental intravillous tissue and associated with both moderate and severe placental dysfunction. TLR3 pathway functionality in the decidua and placenta was confirmed by TLR3 ligand-induced cytokine response, but the TLR3 expression levels did not correlate between the two sites. In conclusion, functional TLR3 was broadly expressed by maternal and fetal cells at both sites of the maternal-fetal interface and the placental intravillous expression was increased in preeclampsia. This suggests TLR3-mediated inflammatory involvement with local regulation at both sites of the maternal-fetal interface in normal and preeclamptic pregnancies.

Postpartum lifestyle interventions among women with pre-eclampsia: a scoping review protocol

INTRODUCTION

Compared to women with normotensive pregnancies, women with a history of pre-eclampsia have a roughly fourfold increased risk of developing chronic arterial hypertension and a twofold increased risk of developing cardiovascular disease (CVD). Lifestyle changes, such as increased physical activity, weight loss, smoking cessation and healthy diet, are effective for CVD prevention in the general population. However, no scoping review or systematic review of postpartum lifestyle interventions among women with pre-eclampsia have, to our best knowledge, been performed. The objective of this scoping review is to provide an overview of the available research literature on postpartum lifestyle interventions to reduce the risk of CVD among women with pre-eclampsia.

METHODS AND ANALYSIS

The protocol is based on the framework outlined by Arksey and O'Malley. Databases to be searched include: PubMed, Embase CINAHL and the JBI Database of Systematic Reviews and Implementation Reports. The search will be performed after the publication of this protocol (estimated to be 1 June 2020) and will be repeated 1 month prior to the submission for publication of the final review (estimated to be 1 January 2021). The review will consider studies that include women in the postpartum period (in particular, but not restricted to, the first 12 months after delivery), with a history of pre-eclampsia. Data will be extracted by two independent reviewers using a data extraction tool including specific details about the population, concept, context, study methods and key findings relevant to the review objective. Any disagreements between the reviewers will be resolved through discussion, or with a third reviewer. The extracted data will be presented in diagrammatic or tabular form that align with the objective of this scoping review. A narrative summary will accompany the tabulated and/or charted results and will describe how the results relate to the reviews objective and questions.

ETHICS AND DISSEMINATION

Since all data will be obtained from publicly available materials, the proposed scoping review does not require ethical approval. The results will be submitted for publication in an open-access peer-reviewed journal and presented at relevant conferences.

Term complications and subsequent risk of preterm birth: registry based study

OBJECTIVE

To explore conditions and outcomes of a first delivery at term that might predict later preterm birth.

DESIGN

Population based, prospective register based study.

SETTING

Medical Birth Registry of Norway, 1999-2015.

PARTICIPANTS

302 192 women giving birth (live or stillbirth) to a second singleton child between 1999 and 2015.

MAIN OUTCOME MEASURES

Main outcome was the relative risk of preterm delivery (<37 gestational weeks) in the birth after a term first birth with pregnancy complications: pre-eclampsia, placental abruption, stillbirth, neonatal death, and small for gestational age.

RESULTS

Women with any of the five complications at term showed a substantially increased risk of preterm delivery in the next pregnancy. The absolute risks for preterm delivery in a second pregnancy were 3.1% with none of the five term complications (8202/265 043), 6.1% after term pre-eclampsia (688/11 225), 7.3% after term placental abruption (41/562), 13.1% after term stillbirth (72/551), 10.0% after term neonatal death (22/219), and 6.7% after term small for gestational age (463/6939). The unadjusted relative risk for preterm birth after term pre-eclampsia was 2.0 (95% confidence interval 1.8 to 2.1), after term placental abruption was 2.3 (1.7 to 3.1), after term stillbirth was 4.2 (3.4 to 5.2), after term neonatal death was 3.2 (2.2 to 4.8), and after term small for gestational age was 2.2 (2.0 to 2.4). On average, the risk of preterm birth was increased 2.0-fold (1.9-fold to 2.1-fold) with one term complication in the first pregnancy, and 3.5-fold (2.9-fold to 4.2-fold) with two or more complications. The associations persisted after excluding recurrence of the specific complication in the second pregnancy. These links between term complications and preterm delivery were also seen in the reverse direction: preterm birth in the first pregnancy predicted complications in second pregnancies delivered at term.

CONCLUSIONS

Pre-eclampsia, placental abruption, stillbirth, neonatal death, or small for gestational age experienced in a first term pregnancy are associated with a substantially increased risk of subsequent preterm delivery. Term complications seem to share important underlying causes with preterm delivery that persist from pregnancy to pregnancy, perhaps related to a mother's predisposition to disorders of placental function.

Implementing a healthy postpartum lifestyle after gestational diabetes or preeclampsia: a qualitative study of the partner's role

Background

Women with preeclampsia (PE) and gestational diabetes mellitus (GDM) are at increased risk for later cardiovascular disease, and lifestyle measures are recommended to prevent subsequent disease. Partner support has been shown to be important in lifestyle modification in other diseases, but there is a lack of knowledge of partner involvement in PE and GDM. The aim of this study was to explore the partner’s experiences and knowledge of gestational diseases, and how the partner wishes to contribute to lifestyle change.

Methods

A qualitative study with one focus group interview and seven in-depth individual interviews, involving eleven partners of women with a pregnancy complicated by GDM or PE. The interview data were inductively analysed using four-step systematic text condensation, supported by interdependence theory.

Results

Partners experienced a strong “we-feeling” and wanted to support the woman in lifestyle changes. At the same time, they felt insecure, worried, foolish and left out and they missed information from clinicians. The partners felt that their involvement was crucial to lasting lifestyle changes and expected that the clinicians would routinely invite them to discuss lifestyle change.

Conclusions

Partners considered themselves an important resource for lifestyle changes for women with PE and GDM, but missed being more directly invited, informed and included in maternity care and wanted to participate in the care that followed the gestational disease. This study can help health professionals to realize that partners are an overlooked resource that can make important contributions to improve the health of the whole family if they are involved and supported by health services.

Preeclampsia, gestational diabetes and later risk of cardiovascular disease: Women's experiences and motivation for lifestyle changes explored in focus group interviews

BACKGROUND

Preeclampsia (PE) and gestational diabetes mellitus (GDM) are both associated with increased risk of future cardiovascular disease (CVD). Knowledge of the relationship between these pregnancy complications and increased CVD risk enables early prevention through lifestyle changes. This study aimed to explore women's experiences with PE and/or GDM, and their motivation and need for information and support to achieve lifestyle changes.

METHODS

Systematic text condensation was used for thematic analysis of meaning and content of data from five focus group interviews with 17 women with PE and/or GDM, with a live birth between January 2015 and October 2017.

RESULTS

This study provides new knowledge of how women with GDM and/or PE experience pregnancy complications in a Nordic healthcare model. It reveals the support they want and the important motivating factors for lifestyle change. We identified six themes: Trivialization of the diagnosis during pregnancy; Left to themselves to look after their own health; The need to process the shock before making lifestyle changes (severe PE); A desire for information about future disease risk and partner involvement; Practical solutions in a busy life with a little one, and; Healthcare professionals can reinforce the turning point. The women with GDM wanted healthcare professionals to motivate them to continue the lifestyle changes introduced during pregnancy. Those with severe PE felt a need for individualized care to ensure that they had processed their traumatic labor experiences before making lifestyle changes. Participants wanted their partner to be routinely involved to ensure a joint understanding of the need for lifestyle changes. Motivation for lifestyle changes in pregnancy was linked to early information and seeing concrete results.

CONCLUSIONS

Women with PE and GDM have different experiences of diagnosis and treatment, which will affect the follow-up interventions to reduce future CVD risk through lifestyle change. For GDM patients, lifestyle changes in pregnancy should be reinforced and continued postpartum. Women with PE should be informed by their general practitioner after birth, and given a plan for lifestyle change. Those with severe PE will need help in processing the trauma, and stress management should be routinely offered.

The two-stage placental model of preeclampsia: An update

Early-onset preeclampsia has been linked to poor placentation and fetal growth restriction, whereas late-onset preeclampsia was suggested to result from maternal factors. We have proposed an alternative model, suggesting that both early- and late-onset preeclampsia result from placental syncytiotrophoblast stress. This stress represents a common endpoint of several Stage 1 processes, promoting the clinical stage 2 of preeclampsia (new-onset hypertension and proteinuria or other signs of end-organ dysfunction), but the causes and timing of placental malperfusion differ. We have suggested that late-onset preeclampsia, without evidence of poor spiral artery remodelling, may be secondary to intraplacental (intervillous) malperfusion due to mechanical restrictions. As the growing placenta reaches its size limit, malperfusion and hypoxia occurs. This latter pathway reflects what is observed in postmature or multiple pregnancies. Our revised two-stage model accommodates most risk factors for preeclampsia including primiparity, chronic pre-pregnancy disease (e.g. obesity, diabetic-, chronic hypertensive-, and some autoimmune diseases), and pregnancy risk factors (e.g. multiple or molar pregnancies, gestational diabetes or hypertension, and low circulating Placental Growth Factor). These factors may increase the risk of progressing to the second stage of preeclampsia (both early- and late-onset) by affecting one of or both pathways leading to Stage 1, as well as potentially accelerating the steps towards Stage 2, including priming the maternal cardiovascular susceptibility to inflammatory factors shed by the placenta. This paper reviews previous preeclampsia findings and concepts, which fit with the revised two-stage model, and argues that "maternal" preeclampsia does not exist, as all preeclampsia requires a placenta.

Prevalence and risk of pre-eclampsia and gestational hypertension in twin pregnancies: a population-based register study

OBJECTIVES

The aim of this study was to assess the prevalence and risk of pre-eclampsia and gestational hypertension in twin pregnancies compared with singleton pregnancies.

DESIGN

Population-based cohort study.

SETTING

Medical Birth Registry of Norway and Statistics Norway.

PARTICIPANTS

929 963 deliveries with 16 174 twin pregnancies in 1999-2014.

METHODS

Pre-eclampsia prevalences in twin and singleton pregnancies were described in percentages. Multivariable regression analyses were performed to assess the risks of pre-eclampsia and gestational hypertension in twin pregnancies compared with those in singleton pregnancies, adjusted for previously known risk factors.

PRIMARY AND SECONDARY OUTCOME MEASURES

Prevalence and risk of pre-eclampsia and gestational hypertension.

RESULTS

The prevalence of pre-eclampsia in the study population was 3.7% (3.4% in singleton pregnancies, 11.8% in twin pregnancies (p=0.001)). The OR for pre-eclampsia in twin pregnancies was three to fourfold compared with singleton pregnancies (OR 3.78; 95% CI 3.59 to 3.96). After adjustment for known risk factors, twin pregnancy remained an independent risk factor for pre-eclampsia (adjusted OR 4.07; 95% CI 3.65 to 4.54). The prevalence of gestational hypertension was 1.7% in women with singleton pregnancies and 2.2% in those with twin pregnancies (OR 1.27; 95% CI 1.14 to 1.41). After adjustment for known risk factors, gestational hypertension was not significantly associated with twin pregnancy.

CONCLUSIONS

The risk of pre-eclampsia in twin pregnancies was three to fourfold compared with singleton pregnancies, regardless of maternal age, parity, educational level, smoking, maternal comorbidity or in vitro fertilisation. The risk of gestational hypertension was not increased in women with twin pregnancies after adjustment for the main risk factors.

Prevalence and associated factors of pre-eclampsia among pregnant women attending anti-natal care at Mettu Karl referal hospital, Ethiopia: cross-sectional study

Background

Preeclampsia is leading causes of maternal and perinatal morbidity and mortality worldwide and it is a hypertensive disorder which usually occurs after 20 weeks of gestation. In Ethiopia, according to Ethiopian National Emergency Obstetric and Newborn Care about 10% of all maternal mortality (direct and indirect) were due to preeclampsia. Despite this condition has adverse effects on the maternal and child health, its prevalence is still significant especially in developing countries including Ethiopia.

Objectives

The aim of the study is to assess the prevalence and associated factors of preeclampsia among pregnant women attending antenatal care at Mettu Karl referral hospital.

Method

The study was conducted at Mettu Karl referral hospital using institutional based cross sectional study design among women whose age was greater or equal to eighteen from March to April 2018. Data were collected from 129 participants by face to face interview technique using structured and pretested questionnaire. Logistic regression analysis was used to identify the factors associated with preeclampsia development.

Result

A total of 129 participants were enrolled in the study with the mean age of 25.87 [SD ± 4.757]. Prevalence of preeclampsia among the current pregnant women who attend ANC in Mettu Karl Hospital were 16 (12.4%) with 95% CI (7, 18). Predictor variables like respondents age (AOR = .009, 95% CI = [.000, .317]), current multiple pregnancy (AOR = .071, 95% CI = [.007, .773]) and history of diabetes mellitus (AOR = .058, 95% CI = [.007–.465]) were significantly associated with the current preeclampsia.

Conclusion

The finding of this study showed that a considerable proportion of women had preeclampsia. Health seeking behavior towards pregnant women’s should be encouraged for both urban and rural residents, which provide a chance to diagnose preeclampsia as early as possible and to prevent the coming complication towards preeclampsia.

Early pregnancy serum levels of perfluoroalkyl substances and risk of preeclampsia in Swedish women

Preeclampsia is a major cause of maternal and fetal morbidity. Emerging research shows an association with environmental exposures. The present aim was to investigate associations between early pregnancy serum levels of perfluoroalkyl substances (PFAS) and preeclampsia. Within the Swedish SELMA study, eight PFAS were measured at median 10 gestational weeks and cases of preeclampsia were postnatally identified from registers. Associations between individual PFAS and preeclampsia were assessed, adjusting for parity, age, weight and smoking. Out of 1,773 women in the study group, 64 (3.6%), developed preeclampsia. A doubling of PFOS and PFNA exposure, corresponding to an inter-quartile increase, was associated with an increased risk for preeclampsia of about 38–53% respectively. Serum PFOS within the highest quartile was associated with an odds ratio of 2.68 (CI 95%: 1.17–6.12), equal to the increased risk associated with nulliparity, when compared to exposure in the first quartile. The same associations were identified, although with higher risk estimates, in analyses restricted to nulliparous women. For other PFAS, there were no associations. In conclusion and consistent with limited previous research only on PFOS, increasing serum levels of PFOS and PFNA during early pregnancy were associated with a clinically relevant risk of preeclampsia, adjusting for established confounders.

Hypertensive disorders of pregnancy and cardiometabolic outcomes in childhood: A systematic review

Background

Hypertensive disorders of pregnancy (HDPs) are among the leading causes of maternal and perinatal morbidity and mortality worldwide and have been suggested to increase long-term cardiovascular disease risk in the offspring.

Objective

The objective of this study was to investigate whether HDPs are associated with cardiometabolic markers in childhood.

Search strategy

PubMed, The Cochrane Library and reference lists of included studies up to January 2019.

Selection criteria

Studies comparing cardiometabolic markers in 2–18-year-old children of mothers with HDP in utero, to children of mothers without HDP.

Data collection and analysis

Sixteen studies reported in 25 publications were included in this systematic review, of which three were considered as having high risk of bias. Thus 13 studies were included in the evidence synthesis: respectively two and eight reported pregnancy induced hypertension and preeclampsia, and three studies reported on both HDPs.

Main results

Most studies (n = 4/5) found a higher blood pressure in children exposed to pregnancy induced hypertension. Most studies (n = 7/10) found no statistically significantly higher blood pressure in children exposed to preeclampsia. No association was found between exposure to HDP and levels of cholesterol, triglycerides or glucose (n = 5/5). No studies investigated an association with (carotid) intima-media thickness, glycated haemoglobin or diabetes mellitus type 2.

Conclusions

Most studies showed that exposure to pregnancy induced hypertension is associated with a higher offspring blood pressure. There is no convincing evidence for an association between exposure to preeclampsia and blood pressure in childhood. Based on current evidence, exposure to HDP is not associated with blood levels of cholesterol, triglycerides and glucose in childhood.

Dietary patterns before and during pregnancy and maternal outcomes: a systematic review

BACKGROUND

Hypertensive disorders of pregnancy (HDP) and gestational diabetes mellitus (GDM) are common maternal complications during pregnancy, with short- and long-term sequelae for both mothers and children.

OBJECTIVE

Two systematic review questions were used to examine the relation between 1) dietary patterns before and during pregnancy, 2) HDP, and 3) GDM.

METHODS

A search was conducted from January 1980 to January 2017 in 9 databases including PubMed, Embase, and Cochrane. Two analysts independently screened articles using a priori inclusion and exclusion criteria; data were extracted from included articles, and risk of bias was assessed. After qualitative synthesis, a conclusion statement was drafted for each question and the evidence supporting the conclusion was graded.

RESULTS

Of the 9103 studies identified, 8 [representing 4 cohorts and 1 randomized controlled trial (RCT)] were included for HDP and 11 (representing 6 cohorts and 1 RCT) for GDM. Limited evidence in healthy Caucasian women with access to health care suggests dietary patterns before and during pregnancy that are higher in vegetables, fruits, whole grains, nuts, legumes, fish, and vegetable oils and lower in meat and refined grains are associated with reduced risk of HDP, including preeclampsia and gestational hypertension. Limited but consistent evidence suggests certain dietary patterns before pregnancy are associated with reduced risk of GDM. These protective dietary patterns are higher in vegetables, fruits, whole grains, nuts, legumes, and fish and lower in red and processed meats. Most of the research was conducted in healthy, Caucasian women with access to health care. Insufficient evidence exists on the associations between dietary patterns before and during pregnancy and risk of HDP in minority women and those of lower socioeconomic status, and dietary patterns during pregnancy and risk of GDM.

CONCLUSIONS

Although some conclusions were drawn from these systematic reviews, more research is needed to address gaps and limitations in the evidence.

Risk of having one lifetime pregnancy and modification by outcome of pregnancy and perinatal loss

INTRODUCTION

With increasing cesarean section rates, adverse pregnancy outcomes such as preterm delivery and small-for-gestational-age continue to be public health challenges. Besides having high co-occurrence and interrelation, it is suggested that these outcomes, along with preeclampsia, are associated with reduced subsequent fertility. On the other hand, the loss of a child during the perinatal period is associated with increased reproduction. Failure to consider this factor when estimating the effects of pregnancy outcomes on future reproduction may lead to erroneous conclusions. However, few studies have explored to what degree a perinatal loss contributes to having a next pregnancy in various adverse pregnancy outcomes.

MATERIAL AND METHODS

This was a population-based study of mothers giving birth to their first singleton infant (≥22 gestational weeks) during 1967-2007 who were followed for the occurrence of a second birth in the Medical Birth Registry of Norway until 2014. Relative risks with 95% confidence intervals for having one lifetime pregnancy by preterm delivery, small-for-gestational-age, preeclampsia and cesarean section were obtained by generalized linear models for the binary family and adjusted for maternal age at first birth, education and year of first childbirth. Main outcome measure was having one lifetime pregnancy.

RESULTS

Nearly 900 000 women gave birth to their first singleton infant in 1967-2007, of which 16% had only one lifetime pregnancy. These women were older at first delivery, had less education and there was a higher proportion of unmarried women than women with two or more births. In women with pregnancy complications where the infant survived the perinatal period, there were the following relative risks for one lifetime pregnancy: increased preterm delivery: 1.21 (1.19-1.22)], small-for-gestational-age: 1.13 (1.12-1.15), preeclampsia: 1.09 (1.07-1.11), cesarean section: 1.24 (1.23-1.25). The risk was significantly reduced if the child was lost (preterm delivery: 0.63 [0.59-0.68], small-for-gestational-age: 0.57 [0.51-0.63], preeclampsia: 0.69 [0.59-0.80], cesarean section: 0.67 [0.56-0.79]), compared with women with no perinatal loss and no adverse outcome.

CONCLUSIONS

The associations between adverse outcomes of pregnancy and the risk of having one lifetime pregnancy were strongly modified by child survival in the perinatal period.

Hypertensive complications of pregnancy: A clinical overview

Hypertensive disorders in pregnancy are a worldwide health problem for women and their infants complicating up to 10% of pregnancies and associated with increased maternal and neonatal morbidity and mortality. In Europe, 2.3-3% of pregnancies are complicated by preeclampsia. Gestational diabetes, obesity, no previous or multiple births, maternal age less than 20 or greater than 35years old and thrombophilia can be some of the possible factors related to increased risk for hypertension in pregnancy. Complications of hypertension during pregnancy affect both mothers and their infants. Ambulatory blood pressure monitoring helps to distinguish true hypertension from the white coat as pregnant women with office abnormal values may have normal out of office blood pressure. Imbalance between proangiogenic and antiangiogenic factors in placenta may lead to endothelial dysfunction, vasoconstriction, activation of the coagulation system, and hemolysis. Carotid intima-media thickness, pulse wave velocity, augmentation index, and arterial wall tension were found to be significantly increased in women with preeclampsia compared to normotensive pregnant women. Uterine artery Doppler and serum biomarkers can be used to evaluate the probability of hypertension and complications during pregnancy, but further research in the field is needed. Lately, micro ribonucleic acids have also been the focus of research as potential biomarkers.

Pre-pregnancy and early pregnancy dietary behavior in relation to maternal and newborn health in the Norwegian Fit for Delivery study - a post hoc observational analysis

Background

Randomized controlled trials targeting maternal dietary and physical activity behaviors during pregnancy have generally failed to accomplish reductions in the prevalence of adverse maternal and neonatal outcomes. Interventions carried out during pregnancy could thus be missing the mark in maximizing intervention health benefit.

Objective

To investigate whether pre-pregnancy and early pregnancy dietary behavior as reported at inclusion into the Norwegian Fit for Delivery (NFFD) trial was associated with maternal and neonatal outcomes irrespective of subsequent randomization assignment.

Design

The study is a post-hoc observational analysis of data from a randomized controlled lifestyle intervention. We constructed two diet scores from participant responses to a 43-item questionnaire that addressed dietary behavior in retrospect (pre-pregnancy diet score) and dietary behavior at inclusion (early pregnancy diet score), respectively. The diet scores ranged from 0 to 10, with higher score reflecting healthier dietary behavior. Associations between diet scores and maternal and neonatal health outcomes were estimated in multivariate logistic regression models.

Results

A total of 591 women were eligible for analysis. A one-point increase in pre-pregnancy diet score was associated with lower odds of excessive gestational weight gain (GWG) (odds ratio [OR]_adj: 0.92; 95% confidence interval [CI]: 0.84-1.00, p = 0.050), preterm delivery (OR_adj: 0.81; 95% CI: 0.68-0.97, p = 0.019), and birthweight ≥ 4,000 g (OR_adj: 0.88; 95% CI: 0.78-0.99, p = 0.038). A one-point increase in early pregnancy diet score was associated with lower odds of excessive GWG (OR_adj: 0.88; 95% CI: 0.79-0.97, p = 0.009), preterm delivery (OR_adj: 0.82; 95% CI: 0.67-0.99, p = 0.038), and preeclampsia (OR_adj: 0.78; 95% CI: 0.62-0.99, p = 0.038).

Discussion

Higher diet score either pre-pregnancy or in early pregnancy was protectively associated with excessive GWG and preterm delivery, whereas the protective association with high birthweight was confined to pre-pregnancy diet and with preeclampsia to early pregnancy diet.

Conclusions

Both pre-pregnancy and early pregnancy dietary behavior was associated with important maternal and neonatal health outcomes in the NFFD dataset.

Preeclampsia and gestational weight gain in the Norwegian Fit for Delivery trial

Objective

Excessive gestational weight gain is linked to risk of preeclampsia, but it is not clear whether the association is causal. The purpose of this paper was to examine gestational weight gain in the Norwegian Fit for Delivery study among women who developed preeclampsia compared to those who did not, and to further explore associations between weight gain and preeclampsia by including data on body composition (bioimpedance) assessed in the last trimester of pregnancy.

Results

A total of 550 women were eligible for the study. Women who developed preeclampsia gained more weight than women who did not (difference 3.7 kg, p = 0.004), with a 3.5 kg difference in total body water observed in week 36 (p = 0.040). Adjusted for age, education, pre-pregnancy body mass index (BMI), randomization, and fat mass, a one kg increase in GWG was associated with 1.3 times higher odds of preeclampsia (OR: 1.31, 95% CI 1.15–1.49, p < 0.001). An independent inverse association between fat mass in week 36 and odds of preeclampsia was observed (OR: 0.79, 95% CI 0.68–0.92, p = 0.002). Given the observed difference in total body water, these findings point to excess fluid as the component driving the association between gestational weight gain and preeclampsia in the present study.

Trial registration The NFFD trial has the Clinical Trials registration: clinicaltrial.gov NCT0100168

Hypertensive pregnancy complications in women with epilepsy and antiepileptic drugs: a population-based cohort study of first pregnancies in Norway

OBJECTIVES

To estimate the risk of hypertensive pregnancy complications in women with epilepsy, with and without antiepileptic drugs, and assess the risk associated with the four most common antiepileptic drugs.

DESIGN

A population-based cohort study using linked data from the Medical Birth Registry of Norway and the Norwegian Prescription Database. Women with epilepsy with and without antiepileptic drugs were compared with women without epilepsy.

SETTING

Norway, 2004-2012.

PARTICIPANTS

All first pregnancies of women with epilepsy and women without epilepsy were included.

PRIMARY AND SECONDARY OUTCOME MEASURES

Main outcome measures were hypertensive pregnancy complications: a compound variable of any hypertensive disorder, gestational hypertension, mild pre-eclampsia, severe pre-eclampsia, early onset pre-eclampsia, eclampsia and HELLP syndrome (haemolysis, elevated liver enzymes, low platelets).

RESULTS

In total, 1778 pregnancies in women with epilepsy and 221 662 in women without epilepsy were analysed. 682 of the women with epilepsy used antiepileptic drugs, the most common in monotherapy being: lamotrigine (n=280), carbamazepine (n=94), levetiracetam (n=71) and valproate (n=51). There was an increased risk of any hypertensive disorder in women with epilepsy (adjusted OR (aOR) 1.2, 95% CI 1.0 to 1.5) and in the subcategory using valproat (aOR 2.9, 95% CI 1.3 to 6.4). The most frequent hypertensive complication was mild pre-eclampsia and the risk was increased in women with epilepsy (aOR 1.4, 95% CI 1.1 to 1.8) and women with epilepsy with valproat (aOR 3.3, 95% CI 1.2 to 9.4).

CONCLUSIONS

Women with epilepsy have an increased risk of mild pre-eclampsia, but not for the severe types of hypertensive pregnancy complications. Lamotrigine and levetiracetam do not predispose for mild pre-eclampsia, whereas valproate was associated with an increased risk of mild pre-eclampsia.

Maternal allergy as an isolated risk factor for early-onset preeclampsia: An epidemiological study

Immunological mechanisms underlying the development of preeclampsia are well known, but no association to allergy has yet been demonstrated. The aim of this study was to assess the correlation between maternal pre-gestational allergy, and early-onset and late-onset preeclampsia, respectively. It was a retrospective cohort study including all women giving birth in the Norwegian cities of Stavanger (1996-2014) and Bergen (2009-2014). Pre-gestational asthma, allergy, other known risk factors for preeclampsia, maternal age and parity were obtained from the electronic medical record system. The main outcome variables were early-onset and late-onset preeclampsia (before and after 34 completed weeks of gestation, respectively). We used multinomial logistic regression to estimate odds ratios (OR) with 95% confidence intervals (95% CI) for early and late-onset preeclampsia in women with pre-gestational allergy when compared to women without allergy, adjusting for covariates. Predicted probabilities for the outcomes were also calculated. Of the 110 064 included pregnancies, 2 799 developed late-onset preeclampsia (2.5%) and 348 developed early-onset preeclampsia (0.3%). Pre-gestational allergy increased the risk of early-onset preeclampsia (OR 1.7, 95% CI 1.3-2.4), and reduced the risk of late-onset preeclampsia (OR 0.8, 95% CI 0.7-0.9). These findings add valuable information on preeclampsia as an immunological complication of pregnancy and corroborate the understanding of early- and late-onset preeclampsia as two different entities.

The limitations of some European healthcare databases for monitoring the effectiveness of pregnancy prevention programmes as risk minimisation measures

PURPOSE

Pregnancy prevention programmes (PPPs) exist for some medicines known to be highly teratogenic. It is increasingly recognised that the impact of these risk minimisation measures requires periodic evaluation. This study aimed to assess the extent to which some of the data needed to monitor the effectiveness of PPPs may be present in European healthcare databases.

METHODS

An inventory was completed for databases contributing to EUROmediCAT capturing pregnancy and prescription data in Denmark, Norway, the Netherlands, Italy (Tuscany/Emilia Romagna), Wales and the rest of the UK, to determine the extent of data collected that could be used to evaluate the impact of PPPs.

RESULTS

Data availability varied between databases. All databases could be used to identify the frequency and duration of prescriptions to women of childbearing age from primary care, but there were specific issues with availability of data from secondary care and private care. To estimate the frequency of exposed pregnancies, all databases could be linked to pregnancy data, but the accuracy of timing of the start of pregnancy was variable, and data on pregnancies ending in induced abortions were often not available. Data availability on contraception to estimate compliance with contraception requirements was variable and no data were available on pregnancy tests.

CONCLUSION

Current electronic healthcare databases do not contain all the data necessary to fully monitor the effectiveness of PPP implementation, and thus, special data collection measures need to be instituted.

Influence of disease activity and medications on offspring birth weight, pre-eclampsia and preterm birth in systemic lupus erythematosus: a population-based study

Objectives

Exploring the associations between disease activity and medications with offspring birth weight, pre-eclampsia and preterm birth in systemic lupus erythematosus (SLE).

Methods

Data from the Medical Birth Registry of Norway (MBRN) were linked with data from RevNatus, a nationwide observational register recruiting women with inflammatory rheumatic diseases. Singleton births in women with SLE included in RevNatus 2006–2015 were cases (n=180). All other singleton births registered in MBRN during this time (n=498 849) served as population controls. Z-score for birth weight adjusted for gestational age and gender was calculated. Disease activity was assessed using Lupus Activity Index in Pregnancy. We compared z-scores for birth weight, pre-eclampsia and preterm birth in cases with inactive disease, cases with active disease and population controls.

Results

Z-scores for birth weight in offspring were lower in inactive (−0.64) and active (−0.53) diseases than population controls (−0.11). Inactive disease did not predict pre-eclampsia while active disease yielded OR 5.33 and OR 3.38 compared with population controls and inactive disease, respectively. Preterm birth occurred more often in inactive (OR 2.57) and active (OR 8.66) diseases compared with population controls, and in active compared with inactive disease (OR 3.36).

Conclusions

SLE has an increased odds for low birth weight and preterm birth, amplified by active disease. The odds for pre-eclampsia is elevated in active, but not inactive disease. This calls for tight follow-up targeting inactive disease before and throughout pregnancy.

The role of KIR and HLA interactions in pregnancy complications

Combinations of KIR and HLA genes associate with pregnancy complications as well as with many other clinical scenarios. Understanding how certain KIR and HLA genes influence the biology of a disease is, however, a formidable challenge. These are the two most variable gene families in the human genome. Moreover, the biology of a disease is best understood by studying the cells of the affected tissue. Natural Killer (NK) cells express KIR and are the most abundant leukocytes in the uterus. Most of our knowledge of NK cells is based on what we have learned from cells isolated from blood, but these are different from their tissue resident counterparts, including uterine NK (uNK) cells. Reproductive immunology faces an additional challenge: Two genotypes must be considered because both maternal and foetal HLA class I molecules may influence the outcome of pregnancy, most likely through interactions with maternal KIR expressed on uNK cells. Maternal uNK cells are not spontaneously cytotoxic and instead engage in interactions with trophoblast. We hypothesise that these interactions regulate allocation of resources between the foetus and the mother and may go wrong in diseases of pregnancy.

Maternal Preeclampsia and Odds of Childhood Cancers in Offspring: A California Statewide Case-Control Study

BACKGROUND

Preeclampsia is a major cause of adverse effects on fetal health. We examined associations between fetal exposure to preeclampsia and subsequent odds of childhood cancers.

METHODS

We obtained childhood cancer cases (n = 13 669) diagnosed at 5 years old or younger between 1988 and 2012 from the California Cancer Registry and linked them to birth certificates. Controls (n = 271 383) were randomly selected from all California births and frequency matched to cases by birth year. We obtained data regarding preeclampsia during pregnancy, labour, and delivery from the medical worksheet of the electronic birth record. We used unconditional logistic regression models with stabilised inverse probability weights to estimate the effect of preeclampsia on each subtype of childhood cancer, taking into account potential confounding by pregnancy characteristics. Marginal structural models were fitted to assess the controlled direct effects of preeclampsia, independent of preterm delivery and NICU admission.

RESULTS

Although a null association was observed for all cancer subtypes combined (odds ratio (OR) 1.0, 95% confidence interval (CI) 0.9, 1.2), preeclampsia was found to be associated with increased odds of two histological subtypes of germ cell tumours: seminomas (OR 8.6, 95% CI 1.9, 38.4) and teratoma (OR 3.0, 95% CI 1.7, 5.4), but not yolk sac tumours in children. Odds remained elevated after adjusting for preterm delivery and NICU admission. Increases in odds were also observed for hepatoblastoma, however this association was attenuated in marginal structural models after accounting for NICU admission.

CONCLUSIONS

These findings suggest that maternal preeclampsia is associated with higher odds of some rare childhood cancers and may shed light on new aetiological factors for these cancers.

Hypertension in Pregnancy and Offspring Cardiovascular Risk in Young Adulthood: Prospective and Sibling Studies in the HUNT Study (Nord-Trøndelag Health Study) in Norway

Women with hypertensive disorders in pregnancy are at increased lifetime risk for cardiovascular disease. We examined the offspring's cardiovascular risk profile in young adulthood and their siblings' cardiovascular risk profile. From the HUNT study (Nord-Trøndelag Health Study) in Norway, 15 778 participants (mean age: 29 years), including 210 sibling groups, were linked to information from the Medical Birth Registry of Norway. Blood pressure, anthropometry, serum lipids, and C-reactive protein were assessed. Seven hundred and six participants were born after exposure to maternal hypertension in pregnancy: 336 mothers had gestational hypertension, 343 had term preeclampsia, and 27 had preterm preeclampsia. Offspring whose mothers had hypertension in pregnancy had 2.7 (95% confidence interval, 1.8-3.5) mm Hg higher systolic blood pressure, 1.5 (0.9-2.1) mm Hg higher diastolic blood pressure, 0.66 (0.31-1.01) kg/m² higher body mass index, and 1.49 (0.65-2.33) cm wider waist circumference, compared with offspring of normotensive pregnancies. Similar differences were observed for gestational hypertension and term preeclampsia. Term preeclampsia was also associated with higher concentrations of non-high-density lipoprotein cholesterol (0.14 mmol/L, 0.03-0.25) and triglycerides (0.13 mmol/L, 0.06-0.21). Siblings born after a normotensive pregnancy had nearly identical risk factor levels as siblings born after maternal hypertension. Offspring born after maternal hypertension in pregnancy have a more adverse cardiovascular risk profile in young adulthood than offspring of normotensive pregnancies. Their siblings, born after a normotensive pregnancy, have a similar risk profile, suggesting that shared genes or lifestyle may account for the association, rather than an intrauterine effect. All children of mothers who have experienced hypertension in pregnancy may be at increased lifetime risk of cardiovascular disease.

Validation of hospital discharge diagnoses for hypertensive disorders of pregnancy

INTRODUCTION

A correct diagnosis of preeclampsia and gestational hypertension is important for treatment and epidemiological studies. Changes in diagnostic criteria and underreporting in certain subsets of patients may hamper validity of the diagnoses.

MATERIALS AND METHODS

We validated the discharge diagnoses of preeclampsia and gestational hypertension, which are reported to the Danish National Patient Registry, in a cohort of 2163 pregnant women by retrospective evaluation of electronic hospital data.

RESULTS

A preeclampsia discharge diagnosis was found in 113 (5.2%) of the participants. After validation, significantly more patients fulfilled criteria for diagnosis of preeclampsia (n = 163, 7.5%, p = 0.002); more had severe preeclampsia, 14 (0.6%) vs. 70 (3.2%), p < 0.001 and gestational hypertension, 62 (2.9%) vs. 46 (2.1%), p = 0.12. The diagnostic sensitivity for preeclampsia by discharge diagnosis was 55.8%; severe preeclampsia 18.6%; gestational hypertension 39.1%. Corresponding positive predictive values were 80.5, 92.9 and 29.0%. Misclassification occurred in 4.3, 2.7 and 3.3%, respectively. Misclassification was more prevalent in obese compared to lean women (10% vs. 3.6%, p < 0.0001).

CONCLUSIONS

Discharge diagnoses substantially underestimated the prevalence of preeclampsia, especially severe preeclampsia. Misclassification was most common in obese preeclamptic women. These findings depict the limitations associated with the direct use of discharge diagnoses of hypertensive disorders in pregnancy for research purposes.

Early-onset preeclampsia appears to discourage subsequent pregnancy but the risks may be overestimated

BACKGROUND

Early-onset preeclampsia is associated with adverse maternal and perinatal outcomes. For women who consider another pregnancy after one complicated by early-onset preeclampsia, the likelihood of recurrence and the subsequent pregnancy outcome for themselves and their babies are pertinent considerations.

OBJECTIVES

The purpose of this study was to determine the subsequent pregnancy rate after a nulliparous pregnancy that was complicated by early-onset preeclampsia and among those who have a subsequent pregnancy, the risk of recurrence by gestational week, and adverse pregnancy outcomes.

STUDY DESIGN

This was a population-based record linkage cohort study. The study population included nulliparous women with a singleton pregnancy and early-onset preeclampsia (<34 weeks gestation) who gave birth in New South Wales Australia from 2001-2010 (the index birth), with follow-up data for a subsequent birth through 2012. Early-onset in the index birth was further categorized as <28 vs 28-33 weeks gestation. Subsequent pregnancy outcomes that were assessed included the pregnancy rate, preeclampsia recurrence, and maternal and perinatal morbidity and mortality rates. The risk of preeclampsia necessitating delivery at each gestational week for women who were at risk was plotted, and the net gain or loss of gestational age when comparing the index with the subsequent pregnancy was calculated.

RESULTS

Among 361,031 nulliparous women with singleton pregnancies, 1473 (0.4%) had early-onset preeclampsia. Women with early-onset preeclampsia in their first pregnancy had a lower subsequent pregnancy rate (59.7%) than women without preeclampsia (67.7%). Of the 758 women with a subsequent singleton birth, 256 (33.8%) experienced preeclampsia in the next pregnancy; 57 women (7.5%) with recurrent early-onset preeclampsia were included. Cumulative rates of preeclampsia in the subsequent pregnancy were higher at every gestation from 23 weeks gestation when the index birth was <28 weeks compared with 28-33 weeks gestation. The cumulative rate and gestation-specific risk of recurrent preeclampsia rose most steeply at 32-38 weeks gestation. Most women (94.6%) progressed to a later gestational age in their subsequent pregnancy. The median overall increase in gestational age at delivery was 6 weeks (interquartile range, 4-8); among women with recurrent preeclampsia, the median increase was 5 weeks (interquartile range, 2-7). Women with index birth <28 weeks gestation compared with 28-33 weeks gestation were more likely to deliver preterm (38.8% vs 28.7%; relative risk, 1.35; 95% confidence interval, 1.04-1.75) and have a perinatal death (4.3% vs 1.2%; relative risk, 3.46; 95% confidence interval, 1.15-10.39) at the subsequent birth, but live born infants had similar rates of severe morbidity (17.1% vs 15.0%; relative risk, 1.14; 95% confidence interval, 0.73-1.79).

CONCLUSION

Women with early-onset preeclampsia in a first pregnancy appear less likely than women without preeclampsia to have a subsequent pregnancy. Maternal and perinatal outcomes in the subsequent pregnancy are generally better than in the first; most women will not have recurrent preeclampsia, and those who do usually will give birth at a greater gestational age compared with their index birth.

Serious maternal complications in relation to severe pre-eclampsia: a retrospective cohort study of the impact of hospital volume

OBJECTIVE

We examined rates of serious maternal complications in relation to severe pre-eclampsia based on the delivering hospital's annualised volume.

DESIGN

Retrospective cohort study.

POPULATION AND SETTING

Singleton deliveries (n = 25 782 235) in 439 hospitals in the USA.

METHODS

Annualised hospital volume was categorised as 25-500, 501-1000, 1001-2000 and >2000.

MAIN OUTCOME MEASURES

Rates of in-hospital maternal death and serious maternal complications, including puerperal cerebrovascular disorders, pulmonary oedema, disseminated intravascular coagulation, acute renal, heart and liver failure, sepsis, haemorrhage and intubation in relation to severe pre-eclampsia. We derived adjusted risk ratio (RR) and 95% confidence interval (CI), from hierarchical Poisson regression models.

RESULTS

Severe pre-eclampsia was associated with an 8.7-fold (95% CI 7.6, 10.1) risk of composite maternal complications, with similar RRs across levels of hospital volumes. However, compared with hospitals with low annual volume (<2000), maternal mortality rates in relation to severe pre-eclampsia were lower in high volume hospitals. The rates of serious maternal complications were 410.7 per 10 000 to women who delivered in hospitals with a high rate of severe pre-eclampsia (≥2.12%) and 584.8 per 10 000 to women who delivered in hospitals with low severe pre-eclampsia rates (≤0.41; RR 1.75, 95% CI 1.24, 2.45).

CONCLUSIONS

While the risks of serious maternal complications in relation to severe pre-eclampsia was similar across hospital delivery volume categories, deaths showed lower rates in large delivery volume hospitals than in smaller volume hospitals. The risk of complications was increased in hospitals with low compared with high severe pre-eclampsia rates.

TWEETABLE ABSTRACT

Hospital volume had little impact on the association between severe pre-eclampsia and maternal complications.

Co-evolution of NK receptors and HLA ligands in humans is driven by reproduction

Allogeneic individuals co-exist during pregnancy in eutherian mammals. Maternal and fetal cells intermingle at the site of placental attachment in the uterus, where the arteries are remodeled to supply the fetus with oxygen and nutrients. This access by placental cells to the maternal supply line determines the growth and birth weight of the baby and is subject to stabilizing selection. Invading placental trophoblast cells express human leukocyte antigen class I ligands (HLA-E, HLA-G, and HLA-C) for receptors on maternal uterine natural killer (NK) and myelomonocytic cells, CD94/NKG2, leukocyte immunoglobulin-like receptor (LILR), and killer immunoglobulin receptor (KIR). Of these, only the KIR/HLA-C system is highly polymorphic. Different combinations of maternal KIR and fetal HLA-C variants are correlated with low birth weight and pre-eclampsia or high birth weight and obstructed labor, the two extremes of the obstetric dilemma. This situation has arisen because of the evolution of bipedalism and subsequently, in the last million years, larger brains. At this point, the human system began to reach a balance between KIR A and KIR B haplotypes and C1 and C2 epitopes of HLA-C alleles that reflects a functional compromise between the competing demands of immunity and reproduction.