Social inequalities in the provision of obstetric services in Norway 1967-2009: a population-based cohort study.

BACKGROUND: Socioeconomic (SE) inequalities have been observed in a number of adverse outcomes of pregnancy and many of the risk factors for such outcomes are associated with a low SE level. However, SE inequalities persist even after adjustment for these risk factors. Less well-off women are more vulnerable, but may also get less adequate health services. The objective of the present study was to assess possible associations between SE conditions in terms of maternal education as well as ethnic background and obstetric care. METHODS: A population-based national cohort study from the Medical Birth Registry of Norway. The study population comprised 2 305 780 births from the observation period 1967-2009. Multilevel analysis was used because of the hierarchical structure of the data. Outcome variables included induction of labour, epidural analgesia, caesarean section, neonatal intensive care and perinatal death. RESULTS: While medical interventions in the 1970s were employed less frequently in women of short education and non-western immigrants, this difference was eliminated or even reversed towards the end of the observation period. However, an excess perinatal mortality in both the short-educated [adjusted relative risk (aRR) = 2.49] and the non-western immigrant groups (aRR = 1.75) remained and may indicate increasing health problems in these groups. CONCLUSION: Even though our study suggests a fair and favourable development during the last decades in the distribution across SE groups of obstetric health services, the results suggest that the needs for obstetric care have increased in vulnerable groups, requiring a closer follow-up.

Low risk pregnancies after a cesarean section: Determinants of trial of labor and its failure.

INTRODUCTION: In pregnancies after a previous cesarean section (CS), a planned repeat CS delivery has been associated with excess risk of adverse outcome. However, also the alternative, a trial of labor after CS (TOLAC), has been associated with excess risks. A TOLAC failure, involving a non-planned CS, carries the highest risk of adverse outcome and a vaginal delivery the lowest. Thus, the decision regarding delivery mode is pivotal in clinical handling of these pregnancies. However, even with a high TOLAC rate, as seen in Norway, repeat CSs are regularly performed for no apparent medical reason. The objective of the present study was to assess to which extent demographic, socioeconomic, and health system factors are determinants of TOLAC and TOLAC failure in low risk pregnancies, and whether any effects observed changed with time. MATERIALS AND METHODS: The study group comprised 24 645 second deliveries (1989-2014) after a first delivery CS. Thus, none of the women had prior vaginal deliveries or more than one CS. Included pregnancies were low risk, cephalic, single, and had gestational age ≥ 37 weeks. Data were obtained from the Medical Birth Registry of Norway (MBRN). The exposure variables were (second delivery) maternal age, length of maternal education, maternal country of origin, size of the delivery unit, health region (South-East, West, Mid, North), and maternal county of residence. The outcomes were TOLAC and TOLAC failure, as rates (%), relative risk (RR) and relative risk adjusted (ARR). Changes in determinant effects over time were assessed by comparing rates in two periods, 1989-2002 vs 2003-2014, and including these periods in an interaction model. RESULTS: The TOLAC rate was 74.9%, with a TOLAC failure rate of 16.2%, resulting in a vaginal birth rate of 62.8%. Low TOLAC rates were observed at high maternal age and in women from East Asia or Latin America. High TOLAC failure rates were observed at high maternal age, in women with less than 11 years of education, and in women of non-western origin. The effects of health system factors, i.e. delivery unit size and administrative region were considerable, on both TOLAC and TOLAC failure. The effects of several determinants changed significantly (P < 0.05) from 1989-2002 to 2003-2014: The association between non-TOLAC and maternal age > 39 years became weaker, the association between short education and TOLAC failure became stronger, and the association between TOLAC failure and small size of delivery unit became stronger. CONCLUSION: Low maternal age, high education, and western country of origin were associated with high TOLAC rates, and low TOLAC failure rates. Maternity unit characteristics (size and region) contributed with effects on the same level as individual determinants studied. Temporal changes were observed in determinant effects.

Perinatal outcome in births after a previous cesarean section at high trial of labor rates.

INTRODUCTION: Trial of labor (TOLAC) is an option in most preganancies after a cesarean section The objective of the study was to compare perinatal outcome in TOLAC and non-TOLAC deliveries in a population with high TOLAC rates. MATERIAL AND METHODS: This was a cohort study based on population data from the Medical Birth Registry of Norway. We included term, cephalic, single, second deliveries, 1989-2009, after a first cesarean section (n = 43 422). TOLAC, TOLAC failure, non-TOLAC deliveries, and after high-risk and low-risk pregnancies (no risk/any risk), were compared with respect to offspring mortality, 5-minute Apgar score Apgar < 7 and < 4, transfer to a neonatal intensive care unit, and neonatal respiratory distress syndrome. RESULTS: Statistically significant differences were observed (P <0.05). In the low-risk group the offspring mortality was 2.3/1000 in TOLAC compared with 0.9/1000 in non-TOLAC. In the high-risk group, the offspring mortality was 3.7/1000 in TOLAC compared with 0.9/1000 in non-TOLAC, and the 5-minute Apgar score < 4 was 3.1/1000 in TOLAC compared with 0.9/1000 in non-TOLAC. In both risk groups, TOLAC delivery had a higher rate of 5-minute Apgar score < 7. In the low-risk group, non-TOLAC deliveries had a higher rate of neonatal respiratory distress syndrome than TOLAC deliveries. CONCLUSIONS: We observed higher risk of offspring mortality and lower 5-minute Apgar score in TOLAC than in non-TOLAC. Possible causes and preventive measures should be explored.

Predicting preeclampsia from a history of preterm birth.

OBJECTIVE: To assess whether women with a history of preterm birth, independent on the presence of prelabour rupture of the membranes (PROM) and growth deviation of the newborn, are more likely to develop preeclampsia with preterm or preterm birth in a subsequent pregnancy. METHODS: We conducted a population-based cohort study, based on Medical Birth Registry of Norway between 1967 and 2012, including 742,980 women with singleton pregnancies who were followed up from their 1st to 2nd pregnancy. In the analyses we included 712,511 women after excluding 30,469 women with preeclampsia in the first pregnancy. RESULTS: After preterm birth without preeclampsia in the first pregnancy, the risk of preterm preeclampsia in the second pregnancy was 4-7 fold higher than after term birth (odds ratios 3.5; 95% confidence interval (CI) 3.0-4.0 to 6.5; 95% CI 5.1-8.2). The risk of term preeclampsia in the pregnancy following a preterm birth was 2-3 times higher than after term birth (odds ratios 1.6; 95% CI 1.5-1.8 to 2.6; 95% CI 2.0-3.4). After spontaneous non-PROM preterm birth and preterm PROM, the risk of preterm preeclampsia was 3.3-3.6 fold higher than after spontaneous term birth. Corresponding risks of term preeclampsia was 1.6-1.8 fold higher. No significant time trends were found in the effect of spontaneous preterm birth in the first pregnancy on preterm or term preeclampsia in the second pregnancy. CONCLUSIONS: The results suggest that preterm birth, regardless of the presence of PROM, and preeclampsia share pathophysiologic mechanisms. These mechanisms may cause preterm birth in one pregnancy and preeclampsia in a subsequent pregnancy in the same woman. The association was particularly evident with preterm preeclampsia.

High birth weight and perinatal mortality among siblings: A register based study in Norway, 1967-2011.

BACKGROUND: Perinatal mortality according to birth weight has an inverse J-pattern. Our aim was to estimate the influence of familial factors on this pattern, applying a cohort sibling design. We focused on excess mortality among macrosomic infants (>2 SD above the mean) and hypothesized that the birth weight-mortality association could be explained by confounding shared family factors. We also estimated how the participant's deviation from mean sibling birth weight influenced the association. METHODS AND FINDINGS: We included 1 925 929 singletons, born term or post-term to mothers with more than one delivery 1967-2011 registered in the Medical Birth Registry of Norway. We examined z-score birth weight and perinatal mortality in random-effects and sibling fixed-effects logistic regression models including measured confounders (e.g. maternal diabetes) as well as unmeasured shared family confounders (through fixed effects models). Birth weight-specific mortality showed an inverse J-pattern, being lowest (2.0 per 1000) at reference weight (z-score +1 to +2) and increasing for higher weights. Mortality in the highest weight category was 15-fold higher than reference. This pattern changed little in multivariable models. Deviance from mean sibling birth weight modified the mortality pattern across the birth weight spectrum: small and medium-sized infants had increased mortality when being smaller than their siblings, and large-sized infants had an increased risk when outweighing their siblings. Maternal diabetes and birth weight acted in a synergistic fashion with mortality among macrosomic infants in diabetic pregnancies in excess of what would be expected for additive effects. CONCLUSIONS: The inverse J-pattern between birth weight and mortality is not explained by measured confounders or unmeasured shared family factors. Infants are at particularly high mortality risk when their birth weight deviates substantially from their siblings. Sensitivity analysis suggests that characteristics related to maternal diabetes could be important in explaining the increased mortality among macrosomic infants.

Risk factors for recurrence of hypertensive disorders of pregnancy, a population-based cohort study.

INTRODUCTION: Hypertensive disorders of pregnancy (HDP) tend to recur from one pregnancy to the next. The aims of the study were to assess the recurrence risk according to type of HDP defined by gestational age at birth and to examine whether recurrence is associated with the following additional risk factors for HDP: maternal age, smoking, inter-delivery interval, diabetes, body mass index, and fetal growth restriction, and to assess temporal trends in these associations. MATERIAL AND METHODS: All women with two singleton births in the Medical Birth Registry of Norway 1967-2012 (n = 742 980) were included in this population-based cohort study. Logistic regression was used to calculate odds ratios for the risk of recurrent HDP according to type of HDP. RESULTS: The highest odds ratio of recurrence was observed for the same type of HDP based on gestational age at delivery. After gestational hypertension and term preeclampsia, the risk for the same type to recur increased 10-fold, whereas after late and early preterm preeclampsia, the risk increased 27- and 97-fold, respectively. The recurrence of early preterm preeclampsia was less influenced by additional risk factors compared with term HDP. Recurrence of early preterm HDP was significantly lower from 1993 onwards. CONCLUSIONS: Recurrent HDP tended to be of the same type as the previous HDP. Risk of recurrence associated with additional risk factors was observed particularly after term. The odds ratio of recurrence of early preterm HDP was significantly lower from 1993 onwards.

Socio-economic risk factors for preterm birth in Norway 1999-2009.

AIMS: Preterm birth is a major cause of perinatal mortality and morbidity and is strongly associated with socio-economic factors. The objective of this study was to examine the associations of maternal education, marital status and ethnicity with preterm birth and to determine the extent to which such associations can be explained by the established risk factors of maternal age, parity and smoking. METHODS: This was a register-based cohort study with data from the Medical Birth Registry of Norway 1999-2009 and Statistics Norway. The sample included all singleton spontaneous births in Norway from 1999 to 2009 (n=494,073). The main outcome measure was preterm birth (gestational age <37 weeks). RESULTS: Low maternal education and single motherhood were associated with preterm birth. After adjustment for the established risk factors, the excess risks were reduced, but remained statistically significant. The relative risk for low education was reduced from 1.50 to 1.36 and for single motherhood from 1.50 to 1.28. Women from Asia had a higher risk of preterm birth than Norwegian-born women (relative risk 1.29) with minor effects of adjustment. CONCLUSIONS SEVERAL SOCIO-ECONOMIC RISK FACTORS ARE ASSOCIATED WITH PRETERM BIRTH IN NORWAY IN ADDITION TO THE ESTABLISHED RISK FACTORS, PRENATAL HEALTH CARE SHOULD FOCUS ON HIGH-RISK GROUPS DEFINED BY MATERNAL EDUCATION, MARITAL STATUS AND ETHNICITY.

Maternal Sick Leave Due to Psychiatric Disorders Following the Birth of a Child With Special Health Care Needs.

OBJECTIVE: Child-related stress following the birth of a child with special health care needs (SHCN) can take a toll on parental health. This study examined how the risk of sick leave due to psychiatric disorders (PD) among mothers of children with SHCN compares with that of mothers of children without SHCN during early motherhood. METHODS: Responses from 58,532 mothers participating in the Norwegian Mother and Child Cohort Study were linked to national registries and monitored for physician-certified sick leave from the month of their child's first birthday until the month of their child's fourth birthday. RESULTS: As compared with mothers of children without SHCN, mothers of children with mild and moderate/severe care needs were at substantial risk of a long-term sick leave due to PD in general and due to depression more specifically. CONCLUSIONS: Extensive childhood care needs are strongly associated with impaired mental health in maternal caregivers during early motherhood.

Breastfeeding surveyed using routine data.

BACKGROUND: The purpose of this study was to investigate breastfeeding as a health indicator through routine data registered at public child health centres. The prevalence and course of breastfeeding were surveyed, as well as factors that affect breastfeeding. MATERIAL AND METHOD: Breastfeeding status at six weeks and six months of age and other routine data were systematically recorded in a newly developed electronic medical records system (Health Profile 0-20 years) for infants attending public child health centres in Bergen in the period 2010-11. This information was linked to data from the Medical Birth Registry. RESULTS: Of 6,093 infants, 73.6% were exclusively breastfed at six weeks of age and 18.9% at six months. In adjusted analyses, there was an association between breastfeeding cessation before six months and the factors smoking, low maternal age, marital status as single, unsatisfactory family situation and social network, and birth weight under 2,500 g. Attendance at a specialist breastfeeding centre and uncertain/abnormal sleep patterns in infants were associated with continued breastfeeding after six months. INTERPRETATION: The medical records system «Health Profile 0-20 years¼, linked to the Medical Birth Registry, was well suited to studying factors that can affect breastfeeding. Mothers and infants with increased need for follow-up were identified.

The association of high birth weight with intelligence in young adulthood: a cohort study of male siblings.

We aimed to explore why, in population studies, the positive association between normal-range birth weight and intelligence becomes negative at the highest birth weights. The study population comprised 217,746 Norwegian male singletons born at term between 1967 and 1976. All had data on birth weight and intelligence quotient (IQ) score at the time of military conscription; 137,574 had data on sibling birth weights; and 62,906 had data on male sibling birth weights. We estimated associations between birth weight and IQ score by ordinary least squares regression for the total study population and by fixed-effects regression for comparisons of brothers. The crude mean IQ score was 1.2 points (95% confidence interval (CI): 0.3, 2.2) lower for those with birth weights of 5,000 g or more compared with the reference group (with birth weights of 4,000-4,499 g). This difference leveled off to 0.0 (95% CI: -0.8, 0.9) in multivariable ordinary least squares regression and reversed to 2.2 points (95% CI: 0.3, 4.2) higher in fixed-effects regression. Results differed mainly because, at a given birth weight, participants who had a sibling with macrosomia had a lower mean IQ score. Nevertheless, within families with 1 or more macrosomic siblings, as in other families, men with higher birth weights tended to have higher IQ scores. Thus, a family-level confounder introduces a cross-level bias that cannot be detected in individual-level studies. We suggest ways in which future studies might elucidate the nature of this confounder.

The Impact of Child Behaviour Problems on Maternal Employment: A Longitudinal Cohort Study.

This prospective population-based study examined associations between children's behaviour problems and maternal employment. Information on children's behaviour problems at 3 years from 22,115 mothers employed before pregnancy and participating in the Norwegian Mother and Child Cohort Study were linked to national register data on employment and relevant social background factors, mothers' self-reported susceptibility to anxiety/depression and mother-reports of day-care attendance and fathers' income. Mothers reporting their child to have severe (>2 SD) internalizing or severe combined behaviour problems (5 %) had excess risk of leaving paid employment irrespective of other important characteristics generally associated with maternal employment (RR 1.24-1.31). The attributable risk percent ranged from 30.3 % (internalizing problems) to 32.4 % (combined problems). Externalizing behaviour problems were not uniquely associated with mothers leaving employment.

Employment trends during preschool years among mothers of term singletons born with low birth weight.

Children born at term with low birth weight (LBW) are regarded growth restricted and are at particular risk of adverse health outcomes requiring a high degree of parental participation in the day-to-day care. This study examined whether their increased risk of special health care needs compared to other children may influence mothers' opportunities for participation in the labor market at different times after delivery. Data from 32,938 participants in the population-based Norwegian Mother and Child Cohort Study with singleton children born at term in 2004-2006 were linked to national registers in order to investigate the mothers' employment status when their children were 1-3 years in 2007 and 4-6 years in 2010. Children weighing less than two standard deviations below the gender-specific mean were defined as LBW children. Although not significantly different from mothers of children in the normal weight range, mothers of LBW children had the overall highest level of non-employment when the children were 1-3 years. At child age 4-6 years on the other hand, LBW was associated with an increased risk of non-employment (RR 1.39: 95 % CI 1.11-1.75) also after adjustment for factors associated with employment in general. In accordance with employment trends in the general population, our findings show that while mothers of normal birth weight children re-enter the labor market as their children grow older, mothers of LBW children born at term participate to a lesser extent in paid employment and remain at levels similar to those of mothers with younger children.

Adaptation to the birth of a child with a congenital anomaly: a prospective longitudinal study of maternal well-being and psychological distress.

This study explores the stability and change in maternal life satisfaction and psychological distress following the birth of a child with a congenital anomaly using 5 assessments from the Norwegian Mother and Child Cohort Study collected from Pregnancy Week 17 to 36 months postpartum. Participating mothers were divided into those having infants with (a) Down syndrome (DS; n = 114), (b) cleft lip/palate (CLP; n = 179), and (c) no disability (ND; n = 99,122). Responses on the Satisfaction With Life Scale and a short version of the Hopkins Symptom Checklist were analyzed using structural equation modeling, including latent growth curves. Satisfaction and distress levels were highly diverse in the sample, but fairly stable over time (retest correlations: .47-.68). However, the birth of a child with DS was associated with a rapid decrease in maternal life satisfaction and a corresponding increase in psychological distress observed between pregnancy and 6 months postpartum. The unique effects from DS on changes in satisfaction (Cohen's d = -.66) and distress (Cohen's d = .60) remained stable. Higher distress and lower life satisfaction at later assessments appeared to reflect a persistent burden that was already experienced 6 months after birth. CLP had a temporary impact (Cohen's d = .29) on maternal distress at 6 months. However, the overall trajectories did not differ between CLP and ND mothers. In sum, the birth of a child with DS influences maternal psychological distress and life satisfaction throughout the toddler period, whereas a curable condition like CLP has only a minor temporary effect on maternal psychological distress.

Risk of cerebral palsy in term-born singletons according to growth status at birth.

AIMS: An excess risk of cerebral palsy (CP) has been reported in children of both low and high birthweight. However, the risk associated with deviations from the mean of other anthropometric measurements has been less well studied. The aim of our study therefore was to determine the association between size measurements at birth and incidence of CP in singletons born at term. METHOD: Standard deviation z-scores for weight, length, head circumference, and ponderal index at birth of term-born singletons born between 1996 and 2006 were calculated using data from the Medical Birth Registry of Norway. The measurements of 398 children with CP recorded in the Cerebral Palsy Registry of Norway were compared with those of 490,022 typically developing infants. RESULTS: Children with low birthweight (p<0.001; <10th centile) as well as low and high z-scores for length (p<0.001 and p<0.001) and head circumference (p<0.001 and p<0.003; <90th centile) had an excess risk of CP, in particular of spastic bilateral CP. Spastic unilateral CP was associated only with low z-scores, whereas children with the greatest body length and largest head circumference, but with low ponderal index, had an excess risk of spastic quadriplegic and dyskinetic CP. INTERPRETATION: Our results are consistent with the notion that most subtypes of CP are due to antenatal factors leading to poor intrauterine growth, whereas CP in children who were large at birth is more likely to be due to intrapartum factors.

Mediators of the association between pre-eclampsia and cerebral palsy: population based cohort study.

OBJECTIVE: To test the hypothesis that pre-eclampsia is a risk factor for cerebral palsy mediated through preterm birth and being born small for gestational age. DESIGN: Population based cohort study. SETTING: Clinical data from the Norwegian Cerebral Palsy Registry were linked with perinatal data prospectively recorded by the Medical Birth Registry of Norway. PARTICIPANTS: All singleton babies who survived the neonatal period during 1996-2006 (849 children with cerebral palsy and 616,658 control children). MAIN OUTCOME MEASURES: Cerebral palsy and cerebral palsy subtypes. RESULTS: Children exposed to pre-eclampsia had an excess risk of cerebral palsy (unadjusted odds ratio 2.5, 95% confidence interval 2.0 to 3.2) compared with unexposed children. Among children born at term (≥ 37 weeks), exposure to pre-eclampsia was not associated with an excess risk of cerebral palsy in babies not born small for gestational age (1.2, 0.7 to 2.0), whereas children exposed to pre-eclampsia and born small for gestational age had a significantly increased risk of cerebral palsy (3.2, 1.5 to 6.7). Non-small for gestational age babies born very preterm (<32 weeks) and exposed to pre-eclampsia had a reduced risk of cerebral palsy compared with unexposed children born at the same gestational age (0.5, 0.3 to 0.8), although the risk was not statistically significantly reduced among children exposed to pre-eclampsia and born small for gestational age (0.7, 0.4 to 1.3). Exposure to pre-eclampsia was not associated with a specific cerebral palsy subtype. CONCLUSIONS: Exposure to pre-eclampsia was associated with an increased risk of cerebral palsy, and this association was mediated through the children being born preterm or small for gestational age, or both. Among children born at term, pre-eclampsia was a risk factor for cerebral palsy only when the children were small for gestational age.

The impact of a child's special health care needs on maternal work participation during early motherhood.

BACKGROUND: Many women temporarily reduce work hours or stop working when caring for small children. However, mothers of children with special health care needs may face particular challenges balancing childrearing responsibilities and employment demands. This study examines how the work participation among mothers of children with special health care needs compares with that of mothers in general during early motherhood, focusing in particular on the extent of the child's additional health care needs. METHODS: By linkage of the population-based Norwegian Mother and Child Cohort Study with national registers on employment, child health care needs, and social background factors, 41,255 mothers employed prior to childbirth were followed until child age 3 years to investigate associations between the child's care needs and mother's dropping out of employment. RESULTS: In total, 16.3% of the formerly employed mothers were no longer employed at child age 3 years. Mothers of children with mild care needs did not differ from mothers in general, whereas mothers of children with moderate [Risk Ratio (RR) 1.45; 95% confidence interval (CI) 1.17, 1.80] and severe care needs [RR 2.19; 95% CI 1.67, 2.87] were at substantial risk of not being employed at follow-up. The impact of the child's health care needs remained strong also after adjusting for several factors associated with employment in general. CONCLUSIONS: Extensive childhood health care needs are associated with reduced short-term employment prospects and remain a substantial influence on mothers' work participation during early motherhood, irrespective of other important characteristics associated with maternal employment.

Cerebral palsy and neonatal death in term singletons born small for gestational age.

BACKGROUND AND OBJECTIVES: To investigate the probable timing of events leading to cerebral palsy (CP) in singletons born small for gestational age (SGA) at term, taking neonatal death into consideration. METHODS: In this registry-based cohort study, data on 400 488 singletons born during 1996-2003 were abstracted from the Medical Birth and the CP registries of Norway. Among 36 604 SGA children (birth weight <10th percentile), 104 died in the neonatal period and 69 developed CP. Apgar scores at 5 minutes, risk factors, MRI findings, and CP subtypes were used to assess the timing of events leading to CP or neonatal death. RESULTS: Intrapartum origin of CP was considered in 5 SGA children (7%; 95% confidence interval: 3-16) in comparison with 31 of 263 (12%; 95% confidence interval: 8-16) non-SGA children (P = .28). The proportions of children who died in the neonatal period after a probable intrapartum event did not differ between the groups when children with congenital malformations were excluded. Probable antenatal events leading to CP and neonatal death were more common among SGA than non-SGA children (P < .001). CONCLUSIONS: In ~90% of children born SGA the event leading to CP is of probable antenatal origin. The low proportion of SGA children with CP after a probable intrapartum event was not outweighed by a higher neonatal mortality rate when congenital malformations were excluded. The higher risk of CP among SGA than among non-SGA children is probably due to a higher prevalence of antenatal risk factors.

Cardiovascular mortality after pre-eclampsia in one child mothers: prospective, population based cohort study.

OBJECTIVE: To assess the association of pre-eclampsia with later cardiovascular death in mothers according to their lifetime number of pregnancies, and particularly after only one child. DESIGN: Prospective, population based cohort study. SETTING: Medical Birth Registry of Norway. PARTICIPANTS: We followed 836,147 Norwegian women with a first singleton birth between 1967 and 2002 for cardiovascular mortality through linkage to the national Cause of Death Registry. About 23,000 women died by 2009, of whom 3891 died from cardiovascular causes. Associations between pre-eclampsia and cardiovascular death were assessed by hazard ratios, estimated by Cox regression analyses. Hazard ratios were adjusted for maternal education (three categories), maternal age at first birth, and year of first birth RESULTS: The rate of cardiovascular mortality among women with preterm pre-eclampsia was 9.2% after having only one child, falling to 1.1% for those with two or more children. With term pre-eclampsia, the rates were 2.8% and 1.1%, respectively. Women with pre-eclampsia in their first pregnancy had higher rates of cardiovascular death than those who did not have the condition at first birth (adjusted hazard ratio 1.6 (95% confidence interval 1.4 to 2.0) after term pre-eclampsia; 3.7 (2.7 to 4.8) after preterm pre-eclampsia). Among women with only one lifetime pregnancy, the increase in risk of cardiovascular death was higher than for those with two or more children (3.4 (2.6 to 4.6) after term pre-eclampsia; 9.4 (6.5 to 13.7) after preterm pre-eclampsia). The risk of cardiovascular death was only moderately elevated among women with pre-eclamptic first pregnancies who went on to have additional children (1.5 (1.2 to 2.0) after term pre-eclampsia; 2.4 (1.5 to 3.9) after preterm pre-eclampsia). There was little evidence of additional risk after recurrent pre-eclampsia. All cause mortality for women with two or more lifetime births, who had pre-eclampsia in first pregnancy, was not elevated, even with preterm pre-eclampsia in first pregnancy (1.1 (0.87 to 1.14)). CONCLUSIONS: Cardiovascular death in women with pre-eclampsia in their first pregnancy is concentrated mainly in women with no additional births. This association might be due to health problems that discourage or prevent further pregnancies rather than to pre-eclampsia itself. As a screening criterion for cardiovascular disease risk, pre-eclampsia is a strong predictor primarily among women with only one child-particularly with preterm pre-eclampsia.

Familial factors in the association between preeclampsia and later ESRD.

BACKGROUND AND OBJECTIVES: Women with preeclampsia have increased risk of developing ESRD. This study assessed whether this can be explained by preeclampsia itself or by familial aggregation of common risk factors. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Since 1967, the Medical Birth Registry of Norway has registered data on all births in the country. By linkage with the Norwegian Population Registry, different, but overlapping, cohorts were defined: the first and second cohorts included women and a sibling (first cohort) or child (second cohort) with a registered first birth between 1967 and 2008. Similar cohorts were defined for men. The Norwegian Renal Registry provided data on ESRD from 1980 to June 2009. RESULTS: Cohort 1 was used for the main analyses and included 570,675 women, 291 of whom developed ESRD after a median 18.2 years. Compared with women without preeclampsia and no siblings with preeclampsia, women without preeclampsia but a sibling with preeclampsia had a relative risk (RR) of ESRD of 0.96 (95% confidence interval, 0.59-1.6), women with preeclampsia but no siblings with preeclampsia had a RR of 6.0 (4.4-8.1), and women with preeclampsia and a sibling with preeclampsia had a RR of 2.8 (0.88-8.6). Further analyses of women showed no increased risk of ESRD if a child had preeclampsia in first pregnancy. CONCLUSIONS: Familial aggregation of risk factors does not seem to explain increased ESRD risk after preeclampsia. These findings support the hypothesis that preeclampsia per se may lead to kidney damage.