Chronic Kidney Disease and Adverse Pregnancy Outcomes: A Systematic Review and Meta-analysis

Objective

Chronic kidney disease (CKD) has been linked with adverse pregnancy outcomes, but few studies have examined the influence of cause and severity. The aim of this meta-analysis was to synthesize the evidence on CKD and adverse pregnancy outcome, by cause and severity of CKD where reported.

Data sources

We searched PubMed, Embase, and Web of Science from inception to May 2021. Study selection and Data Extraction: Studies reporting associations between CKD and adverse pregnancy outcomes were included according to pre-defined eligibility criteria (PROSPERO protocol registration: CRD42020211925). Two reviewers independently screened titles, abstracts, and full-text articles and performed data extraction. The certainty of the evidence was assessed using the GRADE approach.

Main Outcomes and Measures: We used random-effects meta-analyses to calculate pooled estimates. Primary outcomes included pre-eclampsia, Caesarean section (CS), preterm birth (PTB <37 wk.) and small for gestational age (SGA).

Results

In total, 31 studies were included. The certainty of the evidence was deemed to be ‘very low' for all outcomes using the GRADE approach as expected given the observational study design. Pre-pregnancy CKD was associated with pre-eclampsia [pooled adjusted odds ratio (aOR)=2.58 (1.33-5.01)], CS [aOR=1.65 (1.21-2.25)], PTB [aOR=1.73 (1.31-2.27)] and SGA [aOR= 1.93 (1.06-3.52)]. Subgroup analyses suggested that different causes of CKD had differing risks for adverse pregnancy outcomes, and later stages of CKD, compared to earlier stages, were associated with higher odds of pre-eclampsia [crude OR = 2.77 (1.73-4.44)], PTB [4.21 (2.99-5.92)], and SGA [2.43 (1.33-4.46)].

Conclusions

CKD was associated with a higher risk of adverse pregnancy outcomes, and the degree of risk varied by cause and severity. These findings highlight the need for further studies of a more robust quality evaluating the effects of cause and severity of kidney disease on adverse pregnancy outcomes.

Key messages

Pre-pregnancy CKD was associated with higher risk of adverse pregnancy outcomes. The risk of adverse pregnancy outcomes varied by CKD cause and severity.

Placental growth factor in assessment of women with suspected pre-eclampsia to reduce maternal morbidity: a stepped wedge cluster randomised control trial (PARROT Ireland)

OBJECTIVE

To determine whether the addition of placental growth factor (PlGF) measurement to current clinical assessment of women with suspected pre-eclampsia before 37 weeks' gestation would reduce maternal morbidity without increasing neonatal morbidity.

DESIGN

Stepped wedge cluster randomised control trial from 29 June 2017 to 26 April 2019.

SETTING

National multisite trial in seven maternity hospitals throughout the island of Ireland PARTICIPANTS: Women with a singleton pregnancy between 20⁺⁰ to 36⁺⁶ weeks' gestation, with signs or symptoms suggestive of evolving pre-eclampsia. Of the 5718 women screened, 2583 were eligible and 2313 elected to participate.

INTERVENTION

Participants were assigned randomly to either usual care or to usual care plus the addition of point-of-care PlGF testing based on the randomisation status of their maternity hospital at the time point of enrolment.

MAIN OUTCOMES MEASURES

Co-primary outcomes of composite maternal morbidity and composite neonatal morbidity. Analysis was on an individual participant level using mixed-effects Poisson regression adjusted for time effects (with robust standard errors) by intention-to-treat.

RESULTS

Of the 4000 anticipated recruitment target, 2313 eligible participants (57%) were enrolled, of whom 2219 (96%) were included in the primary analysis. Of these, 1202 (54%) participants were assigned to the usual care group, and 1017 (46%) were assigned the intervention of additional point-of-care PlGF testing. The results demonstrate that the integration of point-of-care PlGF testing resulted in no evidence of a difference in maternal morbidity-457/1202 (38%) of women in the control group versus 330/1017 (32%) of women in the intervention group (adjusted risk ratio (RR) 1.01 (95% CI 0.76 to 1.36), P=0.92)-or in neonatal morbidity-527/1202 (43%) of neonates in the control group versus 484/1017 (47%) in the intervention group (adjusted RR 1.03 (0.89 to 1.21), P=0.67).

CONCLUSIONS

This was a pragmatic evaluation of an interventional diagnostic test, conducted nationally across multiple sites. These results do not support the incorporation of PlGF testing into routine clinical investigations for women presenting with suspected preterm pre-eclampsia, but nor do they exclude its potential benefit.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02881073.

Association between preeclampsia and attention-deficit hyperactivity disorder: a population-based and sibling-matched cohort study

OBJECTIVE

To examine the association between preeclampsia and attention-deficit hyperactivity disorder (ADHD), using a large Swedish-based registry cohort.

METHODS

This study comprised 2 047 619 children, with 114 934 (5.6%) cases of ADHD. Preeclampsia was based on two alternate definitions: (i) preeclampsia (using ICD-9/ICD-10) and (ii) preeclampsia and small for gestational age (SGA) combined. ADHD was determined in one of two ways: (i) if a diagnosis of ADHD was present in the National Patient Register or (ii) if an individual was in receipt of ADHD medication in the Prescribed Drug Register. Multivariate Cox proportional hazards regression analysis allowed adjustment for several perinatal/sociodemographic factors. Sibling-matched analysis further controlled for shared genetic and familial confounding.

RESULTS

In the adjusted Cox model, preeclampsia was associated with an increase in likelihood of ADHD (HR: 1.15, 95% CI: 1.12, 1.19). The HR for preeclampsia and those born SGA was 1.43 (95% CI: 1.31, 1.55) in the adjusted model, compared to those unexposed to preeclampsia/SGA. The sibling-matched analysis did not materially change these associations (HR: 1.13, 95% CI: 1.05, 1.22) and 1.55 (95% CI: 1.28, 1.88).

CONCLUSIONS

Exposure to preeclampsia or preeclampsia/SGA was associated with ADHD, independent of genetic/familial factors shared by siblings. However, it is important to note that sibling-matched analysis can only adjust for factors that are constant between pregnancies; therefore, residual confounding cannot be ruled out. Further research is needed to explore modifiable risk factors and identify those most-at-risk babies following delivery.

Preeclampsia and the risk of chronic kidney disease: a national registry-based cohort study

Background

Preeclampsia is associated with increased risk of future cardiovascular disease, but evidence for associations with chronic kidney disease (CKD) has been inconsistent to date. We aimed to measure associations between preeclampsia and long-term CKD in a population-based sample of parous women, and to identify whether the risk differs by CKD subtype.

Methods

Using data from the Swedish Medical Birth Register, singleton live births from 1973-2012 were identified and linked to data from the Swedish Renal Register and National Patient Register (up to 2013). Preeclampsia was the main exposure of interest and was treated as a time-dependent variable. The primary outcome was maternal CKD, and this was classified into 5 subtypes: hypertensive, diabetic, glomerular/proteinuric, tubulo-interstitial, other/non-specific CKD. Cox proportional hazard regression models were used for analysis. Women with pre-pregnancy comorbidities were excluded.

Results

The dataset included 1,924,591 unique women who had 3,726,819 singleton pregnancies. The median follow-up was 20.7 (interquartile range 9.9-30.0) years. Overall, 90,964 women (4.7%) experienced preeclampsia and 18,146 (0.9%) developed CKD. Women who had preeclampsia had higher risk of developing any CKD during follow-up (aHR 1.88, 95% CI 1.79-1.98). The risk differed by CKD subtype, and was higher for hypertensive CKD (aHR 3.76, aHR 3.09-4.57), diabetic CKD (aHR 3.45, 95% CI 2.83-4.21) and glomerular/proteinuric CKD (aHR 2.08, 95% CI 1.90-2.29). Women who had preterm preeclampsia, recurrent preeclampsia, or preeclampsia complicated by pre-pregnancy obesity were also at greater risk of any CKD.

Conclusions

Women with a history of preeclampsia are at increased risk of long-term CKD. The risk is most marked for hypertensive CKD, diabetic CKD, and glomerular/proteinuric CKD. The absolute risk of CKD related to preeclampsia is substantial, and these women may warrant systematic renal monitoring in the years following delivery.

Key messages

Preeclampsia is an independent predictor of long-term risk of chronic kidney disease in otherwise healthy parous women. Women with a history of preeclampsia may warrant systematic renal monitoring through additional blood pressure, blood glucose, and proteinuria checks.

Adverse pregnancy outcomes and long-term risk of maternal renal disease: a systematic review

Background

Little is known about the long-term risk of renal disease following adverse pregnancy outcomes, such as hypertensive disorders of pregnancy (HDP), gestational diabetes (GDM) or preterm delivery. We aimed to investigate associations between adverse pregnancy outcomes and maternal chronic kidney disease (CKD) and end-stage kidney disease (ESKD), by synthesising results of relevant studies.

Methods

A systematic search of PubMed, EMBASE and Web of Science was done up to July 2018. Case-control and cohort studies were eligible for inclusion if they provided original effect estimates for associations between adverse pregnancy outcomes (HDP, GDM, preterm) and maternal renal disease (primary outcomes: CKD, ESKD; secondary outcomes: renal hospitalisation, renal mortality). Two independent reviewers extracted data and assessed risk of bias. Random effects meta-analyses were conducted to determine pooled adjusted odds ratio (AOR) and 95% confidence interval (95%CI) for each association.

Results

Of 5,120 studies retrieved, 21 studies met inclusion criteria (4,483,847 participants). HDP was associated with increased odds of ESKD (AOR 6.58, 95%CI 4.06-10.65), CKD (AOR 2.08, 95%CI 1.06-4.10), renal hospitalisation (AOR 2.29, 95%CI 1.42-3.71). The magnitude of association was dependent on HDP subtype: AOR for preeclampsia and ESKD was 4.87 (95%CI 3.01-7.87); gestational hypertension and ESKD was 3.65 (95%CI 2.34-5.67); other HDP (including chronic hypertension) and ESKD was 14.67 (95%CI 3.21-66.97). Preterm delivery was associated with increased odds of ESKD (AOR 2.16, 95%CI 1.64-2.85). GDM was associated with increased odds of CKD among black women (AOR 1.78, 95%CI 1.18-2.70), but not Caucasian women (AOR 0.81, 95%CI 0.58-1.13)

Conclusions

Women who experience adverse pregnancy outcomes have increased odds of renal disease, especially after HDP. Risk stratification and preventive interventions may be needed to reduce the risk of clinically significant renal disease in mothers.

Key messages

This is the first study to summarise the long-term risk of renal disease among women who experience a range of adverse pregnancy outcomes. Women who experience hypertensive disorders in pregnancy, preterm delivery, or gestational diabetes are at increased odds of renal disease.

Preterm delivery is associated with long-term risk of maternal renal disease

Background

Preterm delivery is an independent risk factor for maternal cardiovascular disease. Little is known about the association between preterm delivery and maternal renal function, and whether any association is independent of preeclampsia or intra-uterine growth restriction. This study aimed to examine the association between gestational age and long-term maternal chronic kidney disease (CKD) and end-stage kidney disease (ESKD).

Methods

Using data from the Swedish Medical Birth Register, singleton live births from 1973-2012 were identified and linked to data from the Swedish Renal Register and National Patient Register (up to 2013). Women with pre-pregnancy CKD/ESKD, cardiovascular disease, diabetes, hypertension, systemic lupus erythematosus were excluded. Gestational age at delivery was the main exposure, treated as a time-dependent variable. Primary outcomes were maternal CKD or ESKD. Cox regression was used, adjusting for maternal age, year of delivery, country of origin, education, parity, interpregnancy interval, smoking, BMI, gestational diabetes. Models were stratified by exposure to preeclampsia or small for gestational age (SGA).

Results

There were 3,847,694 pregnancies among 1,990,273 unique women. Nine percent of women (n = 172,915) had at least one preterm delivery (<37 weeks). Exposure to preterm delivery was associated with higher risk of CKD (aHR 1.48, 95%CI 1.41-1.54) and ESKD (aHR 2.52, 95%CI 2.17-2.92). Earlier gestational age at delivery was associated with increasing risk of CKD and ESKD. Women with spontaneous preterm delivery were at higher risk of CKD (vs. normal term, aHR 1.33, 95% CI 1.26-1.40) and ESKD (aHR 2.02, 95%CI 1.69-2.40) independently of preeclampsia/SGA. Associations persisted after excluding women who developed postpartum cardiovascular disease, hypertension or diabetes.

Conclusions

Women who gave birth at earlier gestation were at higher risk of later CKD and ESKD. This association persisted independently of preeclampsia and SGA.

Key messages

Preterm delivery is an independent predictor of long-term maternal renal disease. Obstetric history should be considered as part of overall risk stratification for chronic kidney disease in women.

Critical review of reporting of the data analysis step in metabolomics

INTRODUCTION

We present the first study to critically appraise the quality of reporting of the data analysis step in metabolomics studies since the publication of minimum reporting guidelines in 2007.

OBJECTIVES

The aim of this study was to assess the standard of reporting of the data analysis step in metabolomics biomarker discovery studies and to investigate whether the level of detail supplied allows basic understanding of the steps employed and/or reuse of the protocol. For the purposes of this review we define the data analysis step to include the data pretreatment step and the actual data analysis step, which covers algorithm selection, univariate analysis and multivariate analysis.

METHOD

We reviewed the literature to identify metabolomic studies of biomarker discovery that were published between January 2008 and December 2014. Studies were examined for completeness in reporting the various steps of the data pretreatment phase and data analysis phase and also for clarity of the workflow of these sections.

RESULTS

We analysed 27 papers, published anytime in 2008 until the end of 2014 in the area or biomarker discovery in serum metabolomics. The results of this review showed that the data analysis step in metabolomics biomarker discovery studies is plagued by unclear and incomplete reporting. Major omissions and lack of logical flow render the data analysis' workflows in these studies impossible to follow and therefore replicate or even imitate.

CONCLUSIONS

While we await the holy grail of computational reproducibility in data analysis to become standard, we propose that, at a minimum, the data analysis section of metabolomics studies should be readable and interpretable without omissions such that a data analysis workflow diagram could be extrapolated from the study and therefore the data analysis protocol could be reused by the reader. That inconsistent and patchy reporting obfuscates reproducibility is a given. However even basic understanding and reuses of protocols are hampered by the low level of detail supplied in the data analysis sections of the studies that we reviewed.

Reporting on data monitoring committees in neonatal randomised controlled trials is inconsistent

AIM

To evaluate the reported use of data monitoring committees (DMCs), the frequency of interim analysis, prespecified stopping rules and early trial termination in neonatal randomised controlled trials (RCTs).

METHODS

We reviewed neonatal RCTs published in four high-impact general medical journals, specifically looking at safety issues including documented involvement of a DMC, stated interim analysis, stopping rules and early trial termination. We searched all journal issues over an 11-year period (2003-2013) and recorded predefined parameters on each item for RCTs meeting inclusion criteria.

RESULTS

Seventy neonatal trials were identified in four general medical journals: Lancet, New England Journal of Medicine (NEJM), British Medical Journal and Journal of American Medical Association. A total of 43 (61.4%) studies reported the presence of a DMC, 36 (51.4%) explicitly mentioned interim analysis, stopping rules were reported in 15 (21.4%) RCTs and seven (10%) trials were terminated early. The NEJM most frequently reported these parameters compared to the other three journals reviewed.

CONCLUSION

While the majority of neonatal RCTs report on DMC involvement and interim analysis, there is still scope for improvement. Clear documentation of safety-related issues should be a central component of reporting in neonatal trials involving newborn infants.

Perinatal determinants of D-dimer levels in a cross-sectional study of low risk pregnant women

BACKGROUND

To examine perinatal determinants of the antenatal levels of D-dimers.

METHODS

Cross-sectional study of 760 low risk pregnant women recruited into five gestational groups. Variables examined in antenatal groups included maternal age, body mass index, parity, smoking, family history venous thromboembolism (VTE) and previous use of the oral contraceptive pill (OCP). Onset of labour and mode of delivery were also examined in the post-natal group.

RESULTS

D-dimer levels in group 4 (38-40 + 6) were significantly lower in the women with a history of taking the OCP when compared to those that had not taken it in the past (P = 0.027). In the day 2 post-natal group, the median level of D-dimer was significantly higher in primparous when compared to multiparous women (P = 0.015). The median D-dimer levels were significantly lower in the elective Caesarean section group in comparison to spontaneous onset (P = 0.003) and induction of labour (P = 0.016). When the mode of delivery was examined, the median D-dimer levels were significantly lower in those that had an elective Caesarean section when compared to normal vaginal delivery (P = 0.008) and instrumental vaginal delivery (P = 0.007). Women post elective Caesarean section had a significantly lower D-dimer than those after emergency Caesarean section (P = 0.008).

DISCUSSION

There are some significant differences in D-dimer levels when certain perinatal determinants are examined. This work is potentially beneficial to the future diagnosis of VTE in pregnancy as it supports previously published recommended D-dimer levels for the diagnosis of VTE in pregnancy.

Parental physical and lifestyle factors and their association with newborn body composition

OBJECTIVE

To investigate the parental physical and lifestyle determinants of newborn body composition.

DESIGN

Prospective cohort study.

SETTING

Cork University Maternity Hospital, a tertiary referral hospital in Cork, Ireland.

POPULATION

All babies were recruited as part of a prospective birth cohort, Babies After

SCOPE

Evaluating the Longitudinal Impact Using Neurological and Nutritional Endpoints (BASELINE). These babies were recruited from women who had participated in the Screening of Pregnancy Endpoints (SCOPE) study Ireland, a prospective, multicentre cohort study

METHODS

Multivariate linear regression was used to analyse the effect of a range of maternal and paternal physical and lifestyle features on neonatal body fat percentage (BF%).

MAIN OUTCOME MEASURES

Neonatal BF%. Neonatal adiposity was assessed within 48 hours of birth using air displacement plethysmography (PEAPOD(®) ).

RESULTS

In all, 1243 infants were enrolled in the study. Increasing maternal body mass index (adjusted mean difference 0.09; 0.04, 0.15) and waist height ratio (adjusted mean difference 6.59; 0.27, 12.92) were significantly associated with increased neonatal BF%. In contrast, maternal smoking was associated with reduced neonatal BF% compared with non smokers (adjusted mean difference -0.55; -1.07, -0.03). Infant sex significantly altered neonatal BF%, with female infants having higher neonatal BF% compared with male infants (adjusted mean difference 1.98; 1.54, 2.53). No association was observed between paternal body mass index (BMI), paternal age or paternal smoking and neonatal BF%.

CONCLUSIONS

Maternal smoking, BMI, waist height ratio and infant sex were associated with altered BF%.

TWEETABLE ABSTRACT

Maternal smoking, BMI, waist height ratio and infant sex are associated with altered neonatal body fat percentage.

Status of the pelvic floor in young primiparous women

OBJECTIVES

To investigate the postnatal prevalence of sonographically diagnosed pelvic floor trauma, and the correlations with various antenatal/intrapartum predictors in primiparous women.

METHODS

This was a prospective cohort study performed in a tertiary hospital with 9000 deliveries per annum. Of those invited, 202 (23.2%) primiparous participants were assessed clinically at least 1 year after delivery by Pelvic Organ Prolapse Quantification (POP-Q), two/three-dimensional transperineal sonography and quantification of serum collagen type III levels.

RESULTS

There was a high prevalence of clinically significant pelvic organ prolapse (POP) on POP-Q staging: uterine prolapse, 63%; cystocele, 42%; and rectocele, 23%. Ballooning of the levator ani muscle (LAM) hiatus was detected in 33% and LAM avulsion in 29% of participants, with partial LAM avulsion occurring in 15% and complete avulsion in 14%. Postnatal POP symptoms (odds ratios (ORs) given here for presence of multiple prolapse symptoms) were positively associated with similar prepregnancy symptoms (OR, 7.2 (95% CI, 1.19-44.33)), LAM avulsion (OR, 4.8 (95% CI, 1.99-11.34)) and forceps delivery (borderline significance; OR, 1.8 (95% CI, 0.96-3.25)) and negatively associated with elective (OR, 0.2 (95% CI, 0.09-0.63)) and emergency (OR, 0.3 (95% CI, 0.12-0.83)) Cesarean section. LAM abnormality was associated with forceps delivery (OR, 4.9 (95% CI, 1.44-16.97)) and prolapse (OR, 6.8-11.7 (95% CI, 2.34-78.51)), whereas collagen levels did not play a role (OR, 1.001 (95% CI, 0.99-1.02)).

CONCLUSIONS

Clinically significant POP was common in relatively young premenopausal primiparous women. Partial or full levator avulsion was seen in 29% of participants and was associated with POP and related symptoms. Congenital factors seem to play little role in the etiology of LAM trauma, and the main risk factor seems to be forceps delivery. Avoidance of difficult vaginal deliveries may prevent severe pelvic floor trauma.

Time to subsequent live birth according to mode of delivery in the first birth

OBJECTIVE

To estimate the rate and time to next live birth by mode of delivery.

DESIGN

Hospital-based cohort.

SETTING

Aarhus University Hospital (AUH), Denmark.

POPULATION

All pregnant women attending AUH were invited to enroll in the Aarhus Birth Cohort (ABC) study between 1989 and 2010 (n = 91,625).

METHODS

Women were followed from their first live birth until the subsequent live birth or until censoring due to study end using Cox regression models.

MAIN OUTCOME MEASURES

Rate and time to subsequent live birth according to mode of delivery.

RESULTS

46,162 index live births were identified, of which 22,462 (49%) had a subsequent live birth. Women with any type of caesarean had a 6% reduction in the rate of subsequent live birth (HR 0.94, 95% CI 0.89, 0.98), which remained unchanged in the analysis by type (emergency, HR 0.95, 95% CI 0.89, 1.02; elective, HR 0.91, 95% CI 0.85, 0.98) compared with women who had a spontaneous vaginal delivery (SVD). Operative vaginal delivery was associated with an 8% reduction in subsequent live birth rates (HR 0.92, 95% CI 0.86, 0.98) and vaginal delivery complicated by shoulder dystocia with a 19% reduction compared with SVD. Median time to next birth in days was shortest in women with a first caesarean (994 days, 95% CI 973, 1026) and longest in women with a vaginal delivery complicated by shoulder dystocia (1065 days, 95% CI 994, 1191). In women with planned pregnancies, the shortest median time to second birth was in women with breech vaginal deliveries (859 days, 95% CI 737, 1089) and the longest in women with vaginal deliveries complicated by shoulder dystocia (1193 days, 95% CI 1028, 1430).

CONCLUSION

The impact of mode of delivery on subsequent rate and time to next birth was minimal in this study. The greatest reduction was among women with assisted vaginal delivery complicated by shoulder dystocia. This study is strengthened by data on pregnancy planning as well as information on complications of pregnancy, delivery and neonatal morbidities, all of which may influence a woman's decision on subsequent birth.

Previous pregnancy loss has an adverse impact on distress and behaviour in subsequent pregnancy

OBJECTIVE

To investigate whether women with previous miscarriages or terminations have higher levels of anxiety, depression, stress, and altered behaviours in a subsequent pregnancy.

DESIGN

A retrospective analysis of 5575 women recruited into the Screening for Pregnancy Endpoints (SCOPE) study, a prospective cohort study.

SETTING

Auckland, New Zealand, Adelaide, Australia, Cork, Ireland, and Manchester, Leeds, and London, UK.

POPULATION

Healthy nulliparous women with singleton pregnancies.

METHODS

Outcomes were recorded at 15 and 20 weeks of gestation.

MAIN OUTCOME MEASURES

Short-form State-Trait Anxiety Inventory (STAI) score, Perceived Stress Scale score, Edinburgh Postnatal Depression Scale score, and pregnancy-related behaviour measured using behavioural responses to pregnancy score.

RESULTS

Of the 5465 women included in the final analysis, 559 (10%) had one and 94 (2%) had two previous miscarriages, and 415 (8%) had one and 66 (1%) had two previous terminations of pregnancy. Women with one previous miscarriage had increased anxiety (adjusted mean difference 1.85; 95% confidence interval, 95% CI 0.61-3.09), perceived stress (adjusted mean difference 0.76; 95% CI 0.48-1.03), depression (adjusted odds ratio, aOR 1.26; 95% CI 1.08-1.45), and limiting/resting behaviour in pregnancy (adjusted mean difference 0.80; 95% CI 0.62-0.97). In women with two miscarriages, depression was more common (aOR 1.65; 95% CI 1.01-2.70) and they had higher scores for limiting/resting behaviour in pregnancy (adjusted mean difference 1.70; 95% CI 0.90-2.53) at 15 weeks of gestation. Women with one previous termination displayed elevated perceived stress (adjusted mean difference 0.65; 95% CI 0.08-1.23) and depression (aOR 1.25; 95% 1.08-1.45) at 15 weeks of gestation. Women with two previous terminations displayed increased perceived stress (adjusted mean difference 1.43; 95% CI 0.00-2.87) and depression (aOR 1.67; 95% 1.28-2.18).

CONCLUSIONS

This study highlights the psychological implications of miscarriage and termination of pregnancy.

Second-trimester maternal distress increases the risk of small for gestational age

BACKGROUND

The effect of prenatal distress on the risk of a small for gestational age (SGA) infant is uncertain. We have addressed the influences of prenatal stress, anxiety and depression on the risk of SGA. We also examined the effects of infant sex and timing of distress during pregnancy on any observed associations.

METHOD

The study population comprised 5606 healthy nulliparous pregnant women who participated in the international prospective Screening for Obstetric and Pregnancy Endpoints (SCOPE) study. Women completed the Perceived Stress Scale (PSS), the short form of the Spielberger State-Trait Anxiety Inventory (STAI) and the Edinburgh Postnatal Depression Scale (EPDS) at 15 ± 1 and 20 ± 1 weeks' gestation. SGA was defined as birthweight below the 10th customized percentile. Logistic regression was used for data analysis, adjusting for several potential confounders such as maternal age, body mass index (BMI), smoking, socio-economic status and physical exercise.

RESULTS

The risk of SGA was increased in relation to mild [adjusted odds ratio (aOR) 1.35, 95% confidence interval (CI) 1.07-1.71], moderate (aOR 1.26, 95% CI 1.06-1.49), high (aOR 1.45, 95% CI 1.08-1.95) and very high stress scores (aOR 1.56, 95% CI 1.03-2.37); very high anxiety score (aOR 1.45, 95% CI 1.13-1.86); and very high depression score (aOR 1.14, 95% CI 1.05-1.24) at 20 ± 1 weeks' gestation. Sensitivity analyses showed that very high anxiety and very high depression increases the risk of SGA in males but not in females whereas stress increases the risk of SGA in both males and females.

CONCLUSIONS

These findings suggest that prenatal stress, anxiety and depression measured at 20 weeks' gestation increase the risk of SGA. The effects of maternal anxiety and depression on SGA were strongest in male infants.

Gestation-specific D-dimer reference ranges: a cross-sectional study

OBJECTIVE

To establish a gestation-specific reference range for D-dimer in healthy pregnant women with a singleton pregnancy using the Auto-Dimer assay.

DESIGN

Cross-sectional study

SETTING

Cork University Maternity Hospital, Ireland.

POPULATION

Healthy pregnant women attending for routine antenatal care.

METHODS

Simultaneous-quantile regression was performed to construct a median, 5th percentile, and 95th percentile, model of normal pregnancy D-dimer concentration versus gestational week, ranging from week 6 to 42. Additionally, pair-wise Mann-Whitney U-tests were performed to compare distributions of D-dimer concentrations for each of the four discrete gestational sampling windows with the distribution of D-dimer concentrations 48 hours postpartum.

MAIN OUTCOME MEASURES

D-dimer concentrations (ng/ml) during normal gestation (approximately week 6 to week 42).

RESULTS

Seven hundred and sixty healthy pregnant women were investigated between gestational age week 5 and 48 hours postpartum. There was a clear steady increase in median D-dimer concentrations over the complete gestational period. Additionally, the 95th centile estimates for all gestational time-points were above the accepted non-pregnancy normal cut-off concentration (224 ng/ml). The results of the Mann-Whitney U-tests suggested that the long-term postnatal return to normal D-dimer concentrations begins in the immediate postpartum period.

CONCLUSIONS

We found that there is a continuous increase in D-dimer concentrations across all gestations. This research is potentially beneficial to future diagnosis of venous thromboembolism (VTE) in pregnancy using the new recommended 95th centile potential cut-offs. Possible further investigation involves an observational study comparing D-dimer concentrations in women with proven DVT with those that don't, generating likelihood ratios.

Maternal serum cholesterol levels are elevated from the 1st trimester of pregnancy: a cross-sectional study

Cholesterol is monitored in the non-pregnant adult population, where normal values are established. Although reported to be elevated in pregnancy, cholesterol is neither routinely measured nor treated. We aimed to investigate cholesterol levels throughout pregnancy and to establish reference values for cholesterol in healthy pregnant women. This was a cross-sectional analysis of serum cholesterol in healthy women with an uncomplicated singleton pregnancy. Pregnant women attending for antenatal care were recruited and cholesterol levels assayed at 12, 20, 28 and 36 weeks' gestation and on day 1-3 postpartum. A total of 222 women were recruited. The majority (95%) were white Irish, with a median age of 31 years (range 16-46). Median BMI was 25.9 kg/m2 (range 18-40) and 16% were smokers. Cholesterol levels were elevated in all trimesters of pregnancy, with median values from 1st trimester raised outside the non-pregnant adult range. High-density lipoprotein (HDL) levels ranged from 0.9 to 3.7 mmol/l and low-density lipoprotein (LDL) levels ranged from 1.3 to 6.1 mmol/l. Fasting, smoking and obesity did not have any significant effects on results. Total and LDL-cholesterol levels were raised throughout pregnancy. Levels were above non-pregnant adult ranges as early as the 1st trimester. The implications of this on fetus and mother are undetermined and deserve further investigation.

Caesarean section and subsequent ectopic pregnancy: a systematic review and meta-analysis

BACKGROUND

Caesarean section rates are increasing worldwide, and the long-term effects are unknown.

OBJECTIVE

To evaluate the risk of subsequent ectopic pregnancy in women with a previous caesarean section, compared with vaginal delivery.

SEARCH STRATEGY

Systematic review of the literature using CINAHL, the Cochrane Library, Embase, Medline, PubMed, SCOPUS and Web of Knowledge, published from 1945 until 17 July 2011.

SELECTION CRITERIA

Cohort and case-control designs reporting on the mode of delivery and subsequent ectopic pregnancy. Two reviewers independently assessed the titles, abstracts, and full articles to identify eligible studies, using a standardised data collection form, and also assessed the study quality. Reference lists of the studies included were also cross-checked.

DATA COLLECTION AND ANALYSIS

Odds ratios (ORs) were combined using a random-effect model to estimate the overall association between caesarean section delivery and the risk of subsequent ectopic pregnancy.

MAIN RESULTS

Thirteen studies were included, which recruited a total of 61,978 women. Five studies reported adjustment for confounding factors, and the pooled OR of subsequent ectopic pregnancy following a caesarean section was 1.05 (95% CI 0.51-2.15). The removal of one study that reported outlier results yielded a pooled OR of 0.82 (95% CI 0.42-1.61). The pooled crude OR for all 13 studies was 1.36 (95% CI 0.99-1.88).

AUTHOR'S CONCLUSIONS

This review found no evidence of an association between prior caesarean section delivery and the occurrence of a subsequent ectopic pregnancy, but the studies included were of poor or variable quality, and only a small number adjusted for potential confounding factors. Further research of a higher methodological quality is required to assess any potential association between mode of delivery and subsequent ectopic pregnancy.

The impact of maternal celiac disease on birthweight and preterm birth: a Danish population-based cohort study

BACKGROUND

Adverse pregnancy outcomes have been associated with maternal celiac disease (CD). In this study, we investigate the effect of treated and untreated maternal CD on infant birthweight and preterm birth.

METHODS

A population-based cohort study consisted of all singleton live births in Denmark between 1 January 1979 and 31 December 2004 was used. A total of 1,504,342 babies were born to 836,241 mothers during the study period. Of those, 1105 babies were born to women with diagnosed CD and 346 were born to women with undiagnosed CD. Women with diagnosed CD were considered as treated with a gluten free diet while women with undiagnosed CD were considered as untreated. The outcome measures were: birthweight, small for gestational age (SGA: birthweight <10th centile), very small for gestational age (VSGA: birthweight <5th centile) and preterm birth. We compared these measures in treated and untreated women with those of a reference group (no history of CD).

RESULTS

Women with untreated CD delivered smaller babies [difference = -98 g (95% CI: -130, -67)], with a higher risk of SGA infants [OR = 1.31 (95% CI: 1.06, 1.63)], VSGA infants [OR = 1.54 (95% CI: 1.17, 2.03)] and preterm birth [OR = 1.33 (95% CI: 1.02, 1.72)] compared with women without CD. Women with treated CD had no increased risk of reduced mean birthweight, risk of delivering SGA and VSGA infants or preterm birth compared with women without CD.

CONCLUSION

Untreated maternal CD increases the risk of reduced birthweight, the risk of delivering SGA and VSGA infants and preterm birth. Diagnosis and presumed treatment of maternal CD with a gluten-free diet appeared to result in a birthweight and preterm birth rate similar to those in women without CD.

Sex ratio at birth following prenatal maternal exposure to severe life events: a population-based cohort study

BACKGROUND

A reduction in the sex ratio at birth has been linked to maternal condition during and before pregnancy. A recent study reported an association between maternal exposure to severe life events and sex ratio at birth using the Danish national register. We attempted to replicate that study using a new Danish cohort.

METHODS

Mothers of all singleton live births (n = 1.35 million births) in Denmark, between 1 January 1980 and 31 December 2002, were linked to data on their children and partners. The old cohort consisted of babies born between 1980 and 1992 (n = 699 362), whereas the new cohort consisted of babies born between 1993 and 2002 (n = 633 451). We defined exposure as death or serious illness in older children and partners in the first trimester or in the 6 months before conception. Sex ratio at birth was defined as the proportion of male live births.

RESULTS

During the study period, there were 1,349,099 singleton live births (692,870 boys and 656,229 girls). The sex ratio at birth in the new cohort was 0.5134. In the new cohort, prenatal exposure to severe life events was not associated with a reduction in the sex ratio at birth [relative risk = 1.00 (95% confidence interval: 0.95-1.05)].

CONCLUSIONS

In the new cohort, we did not find strong evidence that, in a stable western population, prenatal exposure to severe life events is associated with a reduction in the sex ratio at birth.

Rates of preterm birth following antenatal maternal exposure to severe life events: a population-based cohort study

BACKGROUND

Preterm birth and other pregnancy complications have been linked to maternal stress during pregnancy. We investigated the association between maternal exposure to severe life events and risk of preterm birth.

METHODS

Mothers of all singleton live births (n = 1.35 million births) in Denmark between 1 January 1979 and 31 December 2002 were linked to data on their children, parents, siblings and partners. We defined exposure as death or serious illness in close relatives in the first or second trimesters or in the 6 months before conception. Log-linear binomial regression was used to estimate the effect of exposure on preterm birth, very preterm birth and extremely preterm birth.

RESULTS

There were 58 626 (4.34%) preterm births (<37 weeks), 11 732 (0.87%) very preterm births and 3288 (0.24%) extremely preterm births in the study cohort. Severe life events in close relatives in the 6 months before conception increased the risk of preterm birth by 16% (relative risk, RR = 1.16, [95% CI: 1.08-1.23]). Severe life events in older children in the 6 months before conception increased the risk of preterm birth by 23% (RR = 1.23, [95% CI: 1.02-1.49]) and the risk of very preterm birth by 59% (RR = 1.59, [95% CI: 1.08-2.35]).

CONCLUSIONS

Our population-based cohort study suggests that maternal exposure to severe life events, particularly in the 6 months before pregnancy, may increase the risk of preterm and very preterm birth.