Pregnancy outcomes in women with ankylosing spondylitis: a scoping literature and methodological review

Obstetric and neonatal outcomes in women with Ankylosing spondylitis - an evaluation of a population database

BACKGROUND

Ankylosing Spondylitis (AS) is a systemic chronic rheumatic disease characterized by involvement of the axial skeletal and sacroiliac joints. Although this disease is not rare amongst women of reproductive age, data regarding pregnancy outcomes have demonstrated conflicting results. We therefore aimed to compare pregnancy and perinatal outcomes between women who suffered from AS to those who did not.

METHODS

A retrospective cohort study using the Healthcare Cost and Utilization Project, Nationwide Inpatient Sample (HCUP-NIS). Included in the study were all pregnant women who delivered or had a maternal death in the US between 2004 and 2014. Women with an ICD-9 diagnosis of AS before or during pregnancy were compared to those without. Pregnancy, delivery, and neonatal outcomes were compared between the two groups using multivariate logistic regression models adjusting for potential confounders.

RESULTS

A total of 9,096,788 women were inclusion in the analysis. Amongst them, 383 women (3.8/100,000) had a diagnosis of AS and the rest were controls. Women with AS, compared to those without, were more likely to be older; Caucasian; from higher income quartiles; suffer from thyroid disorders, and have multiple pregnancies (p < 0.001, all). After adjusting for confounders, patients in the AS group, compared to those without, had a higher rate of cesarean delivery (CD) (aOR 1.47, 95% CI 1.14-1.91, p = 0.003); gestational diabetes (aOR 1.55, 95% CI 1.02-2.33, p = 0.038); and placenta previa (aOR 3.6, 95% CI 1.6-8.12, p = 0.002). Regarding neonatal outcomes, patients with AS, compared to those without, had a higher rate of small-for-gestational-age (SGA) neonates (aOR 2.19, 95% CI 1.22-3.93, p = 0.009); and intrauterine fetal death (IUFD) (aOR 3.46, 95% CI 1.11-10.83, p = 0.033).

CONCLUSION

Women diagnosed with AS have an increased risk of obstetric complications, including CD, as well as an increased risk of SGA and IUFD.

Machine learning techniques for prediction in pregnancy complicated by autoimmune rheumatic diseases: Applications and challenges

Autoimmune rheumatic diseases are chronic conditions affecting multiple systems and often occurring in young women of childbearing age. The diseases and the physiological characteristics of pregnancy significantly impact maternal-fetal health and pregnancy outcomes. Currently, the integration of big data with healthcare has led to the increasing popularity of using machine learning (ML) to mine clinical data for studying pregnancy complications. In this review, we introduce the basics of ML and the recent advances and trends of ML in different prediction applications for common pregnancy complications by autoimmune rheumatic diseases. Finally, the challenges and future for enhancing the accuracy, reliability, and clinical applicability of ML in prediction have been discussed. This review will provide insights into the utilization of ML in identifying and assisting clinical decision-making for pregnancy complications, while also establishing a foundation for exploring comprehensive management strategies for pregnancy and enhancing maternal and child health.

Reduced T2*-weighted placental MRI predicts foetal growth restriction in women with chronic rheumatic disease-a Danish explorative study

OBJECTIVES

Women with chronic rheumatic disease (CRD) are at greater risk of foetal growth restriction than their healthy peers. T2*-weighted magnetic resonance imaging of placenta (T2*P-MRI) is superior to conventional ultrasonography in predicting birth weight and works as a proxy metabolic mirror of the placental function. We aimed to compare T2*P-MRI in pregnant women with CRD and healthy controls. In addition, we aimed to investigate the correlation between T2*P-MRI and birth weight.

METHODS

Using a General Electric (GE) 1.5 Tesla, we consecutively performed T2*-weighted placental MRI in 10 women with CRD and 18 healthy controls at gestational week (GW)24 and GW32. We prospectively collected clinical parameters during pregnancy including birth outcome and placental weight.

RESULTS

Women with CRD had significantly lower T2*P-MRI values at GW24 than healthy controls (median T2*(IQR) 92.1 ms (81.6; 122.4) versus 118.6 ms (105.1; 129.1), p = 0.03). T2*P-MRI values at GW24 showed a significant correlation with birth weight, as the T2*P-MRI value was reduced in all four pregnancies complicated by SGA at birth. Three out of four pregnancies complicated by SGA at birth remained undetected by routine antenatal ultrasound.

CONCLUSION

This study demonstrates reduced T2*P-MRI values and a high proportion of SGA at birth in CRD pregnancies compared to controls, suggesting an increased risk of placental dysfunction in CRD pregnancies. T2*P-MRI may have the potential to focus clinical vigilance by identifying pregnancies at risk of SGA as early as GW24. Key Points • Placenta-related causes of foetal growth restriction in women with rheumatic disease remain to be investigated. • T2*P-MRI values at gestational week 24 predicted foetuses small for gestational age at birth. • T2*P-MRI may indicate pregnant women with chronic rheumatic disease (CRD) in need of treatment optimization.

Impact of preeclampsia on infant and maternal health among women with rheumatic diseases

OBJECTIVES

We sought to identify the impact of preeclampsia on infant and maternal health among women with rheumatic diseases.

METHODS

A retrospective single-center cohort study was conducted to describe pregnancy and infant outcomes among women with systemic lupus erythematosus (SLE) with and without preeclampsia as compared to women with other rheumatic diseases with and without preeclampsia.

RESULTS

We identified 263 singleton deliveries born to 226 individual mothers (mean age 31 years, 35% non-Hispanic Black). Overall, 14% of women had preeclampsia; preeclampsia was more common among women with SLE than other rheumatic diseases (27% vs 8%). Women with preeclampsia had a longer hospital stay post-delivery. Infants born to mothers with preeclampsia were delivered an average of 3.3 weeks earlier than those without preeclampsia, were 4 times more likely to be born preterm, and twice as likely to be admitted to the neonatal intensive care unit. The large majority of women with SLE in this cohort were prescribed hydroxychloroquine and aspirin, with no clear association of these medications with preeclampsia.

CONCLUSIONS

We found preeclampsia was an important driver of adverse infant and maternal outcomes. While preeclampsia was particularly common among women with SLE in this cohort, the impact of preeclampsia on the infants of all women with rheumatic diseases was similarly severe. In order to improve infant outcomes for women with rheumatic diseases, attention must be paid to preventing, identifying, and managing preeclampsia.

Autoimmune diseases and adverse pregnancy outcomes: an umbrella review

BACKGROUND

There is a high prevalence of autoimmune conditions in women specially in the reproductive years; thus, the association with adverse pregnancy outcomes has been widely studied. However, few autoimmune conditions/adverse outcomes have been studied more than others, and this umbrella review aims to consolidate existing knowledge in this area with the aim to provide new knowledge and also identify gaps in this research area.

METHODS

Medline, Embase, and Cochrane databases were searched from inception to December 2023. Screening, data extraction, and quality appraisal (AMSTAR 2) were done by two independent reviewers. Data were synthesised narratively and quantitatively. Relative risks (RR)/odds ratio (OR) with 95% confidence intervals were reported.

RESULTS

Thirty-two reviews were included consisting of 709 primary studies. The review reported the association between 12 autoimmune conditions and 16 adverse pregnancy outcomes. Higher risk of miscarriage is reported in women with Sjögren's syndrome RR 8.85 (95% CI 3.10-25.26) and systemic lupus erythematosus (SLE) OR 4.90 (3.10-7.69). Pre-eclampsia was reported higher in women with type 1 diabetes mellitus (T1DM) OR 4.19 (3.08-5.71) and SLE OR 3.20 (2.54-4.20). Women reported higher risk of diabetes during pregnancy with inflammatory bowel disease (IBD) OR 2.96 (1.47-5.98). There was an increased risk of intrauterine growth restriction in women with systemic sclerosis OR 3.20 (2.21-4.53) and coeliac disease OR 1.71 (1.36-2.14). Preterm birth was associated with T1DM OR 4.36 (3.72-5.12) and SLE OR 2.79 (2.07-3.77). Low birth weight babies were reported in women with women with SLE or systemic sclerosis OR 5.95 (4.54-7.80) and OR 3.80 (2.16-6.56), respectively. There was a higher risk of stillbirth in women with T1DM OR 3.97 (3.44-4.58), IBD OR 1.57 (1.03-2.38), and coeliac disease OR 1.57 (1.17-2.10). T1DM in women was associated with 32% lower odds of small for gestational age baby OR 0.68 (0.56-0.83).

CONCLUSIONS

Pregnant women with autoimmune conditions are at a greater risk of developing adverse pregnancy outcomes. Further research is required to develop better preconception to postnatal care for women with autoimmune conditions.

Impact of Spondyloarthritis on Pregnancy Outcome: A Descriptive Analysis from a Specialized Center in Qatar

Introduction

Spondyloarthritis (SpA) most commonly presents at childbearing age; thus, pregnancy is of concern. However, data on pregnancy outcomes in these patients are limited.

Purpose

This study aimed to retrospectively describe pregnancy outcomes in patients with SpA from the Middle East.

Patients and Methods

We reviewed the electronic health records of all pregnant women attending a specialized pregnancy and rheumatic disease clinic between 2016 and 2022. All pregnant patients diagnosed with axial spondyloarthritis (axSpA) and peripheral SpA were included. Data on adverse maternal and fetal outcomes were collected.

Results

Fifty-seven eligible pregnancies were identified from hospital records: 10 pregnancies ended in early miscarriage. Forty-seven pregnancies resulted in live singleton births, 25 in patients with peripheral SpA and 22 with axSpA. Human leukocyte antigen B27 was positive in 7 (15%) patients and only in women with axSpA. Twenty-nine (64%) patients received treatment throughout pregnancy. Consistent biologic disease-modifying antirheumatic drug (bDMARD) use was high, in eight (32%) patients with peripheral SpA and in nine (41%) with axSpA. A conventional synthetic disease-modifying anti-rheumatic drug (csDMARD) was used as treatment in 11 (50%) patients with peripheral SpA and two (8%) with axSpA. Twenty-two (53%) neonates were delivered by cesarean section, 19 (40%) by normal vaginal delivery and three (6%) by assisted delivery. Additionally, 44 (94%) deliveries were at term, and 42 (91%) neonates had a normal birth weight. Exploration of a subgroup showed no difference in reported outcomes between patients treated with bDMARD and those treated with csDMARD.

Conclusion

This descriptive study reports a high rate of favorable pregnancy outcomes in patients with SpA. There was no evidence to suggest a difference in pregnancy outcomes between women with axSpA and those with peripheral SpA. This study was one of the first reports from the Middle East. Further studies with larger sample size are warranted.

Drug switching in axial spondyloarthritis patients in Germany - a social listening analysis

Background

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease which primarily affects the axial skeleton resulting in chronic back pain and stiffness. According to the guideline, the first-line treatment includes non-steroidal anti-inflammatory drugs (NSAIDs), conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) and non-pharmacological treatment. Second line treatment involves biological disease-modifying antirheumatic drugs (bDMARDs) such as tumour necrosis factor and interleukin-17 inhibitors.

Objectives

The aim of this social media listening research project was to analyse switches of medication and the reasons thereof to gain valuable insights into real-life journeys of patients suffering from axSpA.

Methods

Publicly available posts in German-speaking disease-specific forums were scanned for disease-specific keywords and commonly used drugs by axSpA patients on the Permea platform. Posts containing at least two key words were selected and switches between medications were manually labelled. A total of 287 scraped posts between 01 July 2010 and 04 Feb 2022 were analysed.

Results

The largest group of described medication switches was initially using bDMARDs. Switches to a different bDMARD, termination of medication and switches to glucocorticoids were most frequently named. Patients on NSAIDs switched to glucocorticoids, a different NSAID or bDMARD, whereas patients on csDMARDs most frequently changed to bDMARDs. In all medication groups the main reason for switching was insufficient efficacy and side effects. Additionally, for the medication groups bDMARDs, csDMARDs and corticosteroids, pregnancy and lactation were given as a reason for switching, whereas patients in the NSAID group never mentioned pregnancy and breastfeeding as a reason for switching treatment.

Conclusion

Our analysis shows medication switches based on real-life patient experiences shared with peers in a social listening setting. We also show medication switches differing from advised guidelines. Gathering real-life insights into patients' journey dealing with chronic diseases allows us to understand, and thereby improve patient care and treatment.

Temporal trends in adverse pregnancy outcomes in axial spondyloarthritis in Sweden: a cohort study

BACKGROUND

Evidence on the risks associated with pregnancy and childbirth in women with axial spondyloarthritis is scarce and conflicting, with more research needed to guide policy and clinical practice. We aimed to assess the risks of adverse pregnancy outcomes in a large cohort of women with axial spondyloarthritis, and to investigate how outcomes varied over time and in relation to anti-rheumatic treatment.

METHODS

In this register-based cohort study, we included births in Sweden between April 1, 2007, and Dec 31, 2020, to women with axial spondyloarthritis and general population comparators, matched 1:10 on year of delivery, maternal age, and parity. Our main data source was the Medical Birth Register (MBR), which includes over 98% of births in Sweden and prospectively collects data on antenatal care, delivery, and foetal outcomes. The information in MBR was linked to other registers, including the National Patient Register, the Prescribed Drug Register, and registers with demographic data. Our main outcomes were the relative risks of adverse pregnancy outcomes, analysed using modified Poisson regression. We also studied how the frequency of certain adverse outcomes, as well as disease-modifying antirheumatic drug (DMARD) and non-steroidal anti-inflammatory drug treatments, changed over the study period by linear regression and loess plots.

FINDINGS

Between April 1, 2007, and Dec 31, 2020, 1580 births in women with axial spondyloarthritis recorded in MBR fulfilled the inclusion criteria and were matched with 15 792 comparator births. Among the 1580 births in women with axial spondyloarthritis, we found increased risks of preterm birth (risk ratio 1·43, 95% CI 1·13-1·80), pre-eclampsia (1·44, 1·08-1·92), elective caesarean delivery (1·59, 1·37-1·84), and serious infant infection (1·29, 1·05-1·59) compared with births in general population comparators. The risks of preterm birth, infant infection, and caesarean delivery decreased by around 0·5 percentage points annually during the study period, while the use of tumour necrosis factor inhibitors during pregnancy increased.

INTERPRETATION

In view of remaining concerns regarding safety of the use of biological DMARDs during pregnancy, we saw a reassuring trend in which pregnancy outcomes improved over time in the axial spondyloarthritis group, concurrent with increased use of biological DMARDs. If the current rate of improvement is maintained, women with axial spondyloarthritis treated in accordance with clinical guidelines might eventually not be at an increased risk of adverse pregnancy outcomes.

FUNDING

Swedish Research Council and The Swedish Rheumatism Association.

Sex bias in lymphocytes: Implications for autoimmune diseases

Autoimmune diseases are characterized by a significant sex dimorphism, with women showing increased susceptibility to disease. This is, at least in part, due to sex-dependent differences in the immune system that are influenced by the complex interplay between sex hormones and sex chromosomes, with contribution from sociological factors, diet and gut microbiota. Sex differences are evident in the number and function of lymphocyte populations. Women mount a stronger pro-inflammatory response than males, with increased lymphocyte proliferation, activation and pro-inflammatory cytokine production, whereas men display expanded regulatory cell subsets. Ageing alters the immune landscape of men and women in differing ways, resulting in changes in autoimmune disease susceptibility. Here we review the current literature on sex differences in lymphocyte function, the factors that influence this, and the implications for autoimmune disease. We propose that improved understanding of sex bias in lymphocyte function can provide sex-specific tailoring of treatment strategies for better management of autoimmune diseases.

Risk of pre-eclampsia and impact of disease activity and antirheumatic treatment in women with rheumatoid arthritis, axial spondylarthritis and psoriatic arthritis: a collaborative matched cohort study from Sweden and Denmark

Objective

To explore the risk of pre-eclampsia in rheumatoid arthritis (RA), axial spondyloarthritis (AxSpA) and psoriatic arthritis (PsA), focusing on the impact of treatment and disease activity.

Methods

We identified RA, AxSpA and PsA singleton pregnancies (2006–2018) by linking medical birth registers to Swedish (SRQ) and Danish (DANBIO) rheumatology registers. Control pregnancies from the medical birth registers were matched 1:10 on maternal age, parity and birth year.

We obtained information on antirheumatic treatment before and during pregnancy and disease activity during pregnancy. Risks of pre-eclampsia in RA, AxSpA and PsA pregnancies, compared with control pregnancies, were estimated overall and by antirheumatic treatment (conventional synthetic disease-modifying antirheumatic drug (DMARD)/biological DMARD/corticosteroids, as monotherapy or combination therapy) and disease load (Health Assessment Questionnaire≥1/C-reactive protein≥10/Disease Activity Score in 28 joints≥3.2) through logistic regression (adjusted ORs (aORs) with 95% CI).

Results

We observed 69, 34, and 26 pre-eclampsia events among RA (n=1739), AxSpA (n=819) and PsA (n=489), resulting in a risk of pre-eclampsia of, respectively, aOR 1.27 (95% CI 0.96 to 1.67), 1.17 (0.76 to 1.78) and 1.85 (1.10 to 3.12), compared with controls.

For RA, maternal combination therapy before and during pregnancy was associated with increased risk (1.59; 1.07 to 2.37 and 1.53; 0.97 to 2.39, respectively). For PsA, maternal monotherapy before pregnancy was associated with pre-eclampsia (2.72; 1.4 to 5.13). In RA pregnancies with available information (43%), high disease load was associated with doubled risk of pre-eclampsia (aOR 1.96; 1.26 to 3.04).

Conclusion

PsA pregnancies, but not AxSpA pregnancies, were at increased risk of pre-eclampsia. For RA, combination therapy (potentially a surrogate for high disease activity both before and during pregnancy) and high disease load during pregnancy might be a risk factor for pre-eclampsia.

Pregnancy and neonatal outcomes in women with axial spondyloarthritis: pooled data analysis from the European Network of Pregnancy Registries in Rheumatology (EuNeP)

OBJECTIVE

To investigate outcome and course of pregnancies in women with axial spondyloarthritis (axSpA) in a pooled data analysis of pregnancy registries in rheumatology.

METHODS

Prospectively followed women with axSpA, fulfilling ASAS classification criteria and for whom a pregnancy outcome was reported, were eligible for the analysis. Anonymised data of four registries was pooled. Rates of adverse pregnancy outcomes were calculated. Systemic inflammation, disease activity and treatment patterns with tumour necrosis factor inhibitor (TNFi) before, during and after pregnancy were analysed.

RESULTS

In a total of 332 pregnancies from 304 axSpA women, 98.8% of the pregnancies resulted in live birth. Mean maternal age was 31 years and disease duration 5 years. Most of these patients received pre-conception counselling (78.4%). Before pregnancy, 53% received TNFi treatment, 27.5% in first and 21.4% in third trimester. Pregnancy and neonatal outcomes were favourable with rates of 2.2% for pre-eclampsia, 4.9% for preterm birth, 3.1% for low birth weight and 9.5% for small for gestational age. Neonates were delivered by caesarean section in 27.7% of pregnancies, of which 47.4% were emergencies. Pooled mean CRP was 4 mg/L before conception peaking in the second trimester at 9.4 mg/L. Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) was below 4 at all time-points.

CONCLUSIONS

Pooled rates of most outcomes were better than what had been reported in the literature and within expected rates of those reported for the general population. Pre-conception counselling, planned pregnancies and a tight management in expert centres applying a tailored treatment approach may have contributed to the favourable pregnancy outcomes.

Maternal and infant outcomes in pregnancies of women with axial spondyloarthritis compared with matched controls: results from nationwide health insurance data

Objectives

To investigate pregnancy outcomes in women with axial spondyloarthritis (axSpA) under different pharmacological treatments in comparison with matched controls.

Methods

Using health insurance data from 2006 to 2019, pregnancy outcomes of women with axSpA were compared with those of age-matched and calendar year-matched controls without axSpA. Women with axSpA were further stratified by treatment prior to delivery and pregnancy outcomes compared. Adjusted ORs (aORs) with 95% CIs were calculated using generalised estimating equation analyses.

Results

A total of 1021 pregnancy outcomes in patients with axSpA were identified (928 deliveries, 80 abortions, 13 ectopic pregnancies) and compared with 10 210 pregnancy outcomes in controls (9488 deliveries, 615 abortions, 147 ectopic pregnancies). Compared with controls, women with axSpA showed higher odds of elective caesarean section (aOR 1.52; 1.25 to 1.85).

Among women with axSpA, the risk of preterm birth was higher under non-steroidal anti-inflammatory drugs (NSAIDs) treatment (aOR 2.22; 1.09 to 4.52) than without any anti-inflammatory treatment. The risks of preterm birth (aOR 4.01; 1.93 to 8.34) and small-for-gestational-age (aOR 3.22; 1.34 to 7.73) were increased under NSAIDs treatment in combination with conventional synthetic disease-modifying anti-rheumatic drugs (DMARDs), steroids or analgesics. Non-significant increased risks of small-for-gestational-age (aOR 1.68; 0.43 to 6.57) and preterm birth (aOR 1.56; 0.51 to 4.83) were found under biological DMARDs.

Conclusions

Women with axSpA have significantly increased odds of caesarean section compared with matched controls. Risks of preterm birth and small-for-gestational-age vary by type of anti-inflammatory treatment.

Managing puerperium in patients with systemic autoimmune diseases: an update

INTRODUCTION

Puerperium is a critical period for patients affected by autoimmune rheumatic diseases for the risk of disease's flares and difficulties in treating lactating mothers. We want to summarize the literature data about psychological and pharmacological management of these patients and possible risk factors of disease's flares.

AREAS COVERED

We made a narrative review on recent studies about puerperium in rheumatic autoimmune diseases patients.

EXPERT OPINION

The physicians involved in management of patients during puerperium and in the follow-up of babies need to agree on maternal treatment because they need to reassure mothers about the safety of the prescribed medications. Furthermore, women with rheumatic diseases could present some musculoskeletal limitations and psychological problems, such as postpartum depression, which can lead to a sense of inadequacy to the mother's task. Families and physicians should be aware of these possible complications and support the new mothers providing correct counseling and practical help.

Safety of anti-TNF agents in pregnancy

Inflammatory bowel disease, rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, and psoriasis are associated with adverse pregnancy outcomes. Active maternal disease during pregnancy is associated with additional negative outcomes. Anti-TNF agents are effective treatments for inflammatory bowel disease, rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, and psoriasis. These agents cross the placenta starting in the second trimester, with levels detected for several months after birth. This has led to safety concerns, with continued therapy during pregnancy for both the mother and the infant. This review covers retrospective and prospective data published from various cohorts of pregnant women exposed to anti-TNF agents during pregnancy. It highlights the safety of anti-TNF drugs in pregnancy, breast-feeding, and during the first year of life of the infant.

Fertility and pregnancy outcomes in women with spondyloarthritis: a systematic review and meta-analysis

OBJECTIVE

To determine the impact of spondyloarthritis (SpA) and its treatments on fertility and pregnancy outcomes, as well as the impact of pregnancy on disease activity.

METHODS

A systematic review and meta-analyses were performed, including studies in women with SpA (axial (axSpA) and peripheral SpA, including psoriatic arthritis (PsA)). The heterogeneity between studies was quantified (I2), and in case of substantial heterogeneity, the results were reported in a narrative review.

RESULTS

Within 4397 eligible studies, 21 articles were included, assessing overall 3566 patients and 3718 pregnancies compared to 42264 controls. Fertility suffers from a lack of data in the literature. We found an increased risk of preterm birth (pooled OR 1,64 [1,15-2,33], I2 =24% in axSpA and 1,62 [1,23-2,15], I2 =0,0% in PsA), small for gestational age (pooled OR 2,05, [1,09-3,89], I2 =5,8% in axSpA), preeclampsia (pooled OR 1,59, [1,11-2,27], I2 =0% in axSpA) and caesarean section (pooled OR 1,70 [1,44-2,00], I2 =19,9% in axSpA and 1,71 [1,14-2,55], I2 =74,3% in PsA), without any other unfavourable pregnancy outcome. Further analysis showed a significant higher risk for elective caesarean (pooled OR 2,64, [1,92-3,62], I2 =0,0% in axSpA and 1,47, [1,15-1,88], I2 =0,0% in PsA), without increased risk for emergency caesarean in PsA. During pregnancy, there appears to be a tendency for unchanged or worsened disease activity in axSpA and unchanged or improved disease activity in PsA. Both conditions tend to flare in postpartum period.

CONCLUSION

SpA seems to be associated with an increased risk of preterm birth, small for gestational age, preeclampsia, and caesarean section.