Low-dose aspirin use in pregnancy and the risk of preterm birth: a Swedish register-based cohort study

In utero aspirin exposure and child neurocognitive development: A propensity score-matched analysis

OBJECTIVE

To evaluate the association between a short-period, high-dose in utero aspirin exposure and child neurocognitive development.

DESIGN

A propensity score-matched analysis of a multicentre prospective cohort study.

SETTING

The US Collaborative Perinatal Project (1959-1976).

POPULATION

A total of 50 565 singleton live births with maternal information.

METHODS

We performed a propensity score matching to balance maternal characteristics between women with and without aspirin exposure. Inverse probability-weighted marginal structural models were used to estimate associations between aspirin exposure and child neurocognitive assessments.

MAIN OUTCOME MEASURES

Child neurocognitive development was assessed using the Bayley Scales at 8 months, the Stanford Binet Intelligence Scale at 4 years, and the Wechsler Intelligence Scale and Wide-Range Achievement Test (WRAT) at 7 years.

RESULTS

Children exposed to aspirin in utero were associated with an 8%-16% reduced risk of having suspect/abnormal or below-average scores in most neurocognitive assessments. A trend of lower risks of having suspect/abnormal or below-average scores was further observed in children with in utero aspirin exposure for more than 7 days, particularly on Bayley Mental (relative risk [RR] 0.82, 95% CI 0.74-0.92), WRAT Reading (RR 0.88, 95% CI 0.78-0.98) and WRAT Arithmetic tests (RR 0.76, 95% CI 0.66-0.86). This association was mainly observed in the second trimester of pregnancy.

CONCLUSIONS

In utero aspirin exposure was associated with improved child neurocognitive development in a prospective cohort study. Further studies are warranted to evaluate the impact of long-period and low-dose in utero aspirin exposure on child short- and long-term neurodevelopment.

The effects of low-dose aspirin on preterm birth: a systematic review and meta-analysis of randomized controlled trials

AIM

To conduct a systematic review and meta-analysis of all randomized controlled trials (RCTs) that evaluated the efficacy of low-dose aspirin (LDA, ≤ 160 mg/day) on preventing preterm birth (PB).

METHODS

Five databases were screened from inception until June 25, 2023. The RCTs were assessed for quality according to Cochrane's risk of bias tool. The endpoints were summarized as risk ratio (RR) with 95% confidence interval (CI).

RESULTS

Overall, 40 RCTs were analyzed. LDA significantly decreased the risk of PB < 37 weeks (RR: 0.91, 95% CI 0.87, 0.96, p < 0.001, moderate certainty of evidence) with low between-study heterogeneity (I2 = 23.2%, p = 0.11), and PB < 34 weeks (RR: 0.78, 95% CI 0.61, 0.99, p = 0.04, low certainty of evidence) with high between-study heterogeneity (I2 = 58.3%, p = 0.01). There were no significant differences between both groups regarding the risk of spontaneous (RR: 0.94, 95% CI 0.83, 1.07, p = 0.37) and medically indicated (RR: 1.28, 95% CI 0.87, 1.88, p = 0.21) BP < 37 weeks. Sensitivity analysis revealed robustness for all outcomes, except for the risk of PB < 34 weeks. For PB < 37 weeks and PB < 34 weeks, publication bias was detected based on visual inspection of funnel plots for asymmetry and statistical significance for Egger's test (p = 0.009 and p = 0.0012, respectively).

CONCLUSION

LDA can significantly reduce the risk of PB < 37 and < 34 weeks. Nevertheless, further high-quality RCTs conducted in diverse populations, while accounting for potential confounding factors, are imperative to elucidate the optimal aspirin dosage, timing of initiation, and treatment duration for preventing preterm birth and to arrive at definitive conclusions.

The NFκB Signaling Pathway Is Involved in the Pathophysiological Process of Preeclampsia

The high prevalence of preeclampsia (PE) is a major cause of maternal and fetal mortality and affects the long-term prognosis of both mother and baby. Termination of pregnancy is currently the only effective treatment for PE, so there is an urgent need for research into its pathogenesis and the development of new therapeutic approaches. The NFκB family of transcription factors has an essential role in inflammation and innate immunity. In this review, we summarize the role of NFκB in normal and preeclampsia pregnancies, the role of NFκB in existing treatment strategies, and potential NFκB treatment strategies.

First-trimester prediction of preterm pre-eclampsia and prophylaxis by aspirin: Effect on spontaneous and iatrogenic preterm birth

OBJECTIVE

To report the predictive performance for preterm birth (PTB) of the Fetal Medicine Foundation (FMF) triple test and National Institute for health and Care Excellence (NICE) guidelines used to screen for pre-eclampsia and examine the impact of aspirin in the prevention of PTB.

DESIGN

Secondary analysis of data from the SPREE study and the ASPRE trial.

SETTING

Multicentre studies.

POPULATION

In SPREE, women with singleton pregnancies had screening for preterm pre-eclampsia at 11-13 weeks of gestation by the FMF method and NICE guidelines. There were 16 451 pregnancies that resulted in delivery at ≥24 weeks of gestation and these data were used to derive the predictive performance for PTB of the two methods of screening. The results from the ASPRE trial were used to examine the effect of aspirin in the prevention of PTB in the population from SPREE.

METHODS

Comparison of performance of FMF method and NICE guidelines for pre-eclampsia in the prediction of PTB and use of aspirin in prevention of PTB.

MAIN OUTCOME MEASURE

Spontaneous PTB (sPTB), iatrogenic PTB for pre-eclampsia (iPTB-PE) and iatrogenic PTB for reasons other than pre-eclampsia (iPTB-noPE).

RESULTS

Estimated incidence rates of sPTB, iPTB-PE and iPTB-noPE were 3.4%, 0.8% and 1.6%, respectively. The corresponding detection rates were 17%, 82% and 25% for the triple test and 12%, 39% and 19% for NICE guidelines, using the same overall screen positive rate of 10.2%. The estimated proportions prevented by aspirin were 14%, 65% and 0%, respectively.

CONCLUSION

Prediction of sPTB and iPTB-noPE by the triple test was poor and poorer by the NICE guidelines. Neither sPTB nor iPTB-noPE was reduced substantially by aspirin.

Pregnancy-associated cardiovascular risks and postpartum care; an opportunity for interventions aiming at health preservation and disease prevention

Cardiovascular disease (CVD) is the leading cause of premature death and disability for female individuals around the world and the rates are increasing in those aged 35-44 years. Certain pregnancy complications (Pregnancy-associated Cardiovascular Risks (P-CVR))are linked to an increased risk of future CVD making pregnancy and the postpartum period as an ideal time to screen individuals for underlying, often unrecognized, cardiovascular risk factors. Pregnancy complications associated with an increased risk of future CVD including the hypertensive disorders of pregnancy, gestational diabetes, idiopathic preterm birth, delivery of a growth restricted baby and a placental abruption that leads to delivery. A number of guidelines and research groups recommend postpartum CVR screening, counseling and lifestyle intervention for all those who have had one or more of P-CVRs starting within the first six months postpartum. An individualized plan for postpartum screening should be created with the individual and lifestyle interventions discussed.

Potential impact on using aspirin as the primary prevention of adverse pregnancy outcomes in twins conceived using ART

With the development of assisted reproductive technology, the number of twin pregnancies is increasing year by year. Given the increased risk of pregnancy complications associated with twin pregnancies, and the fact that these babies are rare and difficult to obtain through assisted reproductive technology, clinicians urgently require finding effective and safe drugs to improve pregnancy outcomes. Low-dose aspirin can not only promote placental blood supply, but also effectively anti-inflammatory. Whether Low-dose aspirin can effectively reduce the risk of pregnancy complications in this special group needs to be clarified. We therefore retrospectively analyzed 665 twin pregnancies from assisted reproduction technology, grouped according to aspirin use, and followed pregnancy outcomes to assess bleeding risk. Low-dose aspirin was found to be effective in preventing preeclampsia without a significant risk of bleeding. However, aspirin does not prevent specific complication in twin pregnancies and seems to have a better preventive effect only when the mother is under 30, which should alarm clinicians should not blindly using aspirin in this particular group.

First trimester risk of preeclampsia and rate of spontaneous birth in patients without preeclampsia

BACKGROUND

First-trimester screening for preeclampsia using a combination of maternal risk factors and mean arterial pressure, uterine artery pulsatility index, and placental growth factor, as proposed by the Fetal Medicine Foundation, provides effective prediction of preterm preeclampsia. Placental dysfunction is a potential precursor of spontaneous birth.

OBJECTIVE

The objective of this study was to examine if the estimated risk of preeclampsia is associated with the gestational age at onset of spontaneous delivery in the absence of preeclampsia.

STUDY DESIGN

This was a secondary analysis of the data from the Screening programme for pre-eclampsia trial in which there was a comparison of the performance of first-trimester screening for preterm preeclampsia using the Fetal Medicine Foundation model vs a traditional history-based risk scoring system. A subgroup of women from the trial with spontaneous onset of delivery (labor with intact membranes or preterm prelabor rupture of membranes) was included in this study and was arbitrarily divided into 3 groups according to the risk for preterm preeclampsia as determined by the Fetal Medicine Foundation model at 11 to 13 weeks' gestation as follows: group 1 low risk (˂1/100); group 2 intermediate risk (1/50 to 1/100); and group 3 high risk (˃1/50). A survival analysis was carried out using a Kaplan-Meier estimator and a Cox regression analysis with stratification by the 3 preeclampsia risk groups. Occurrence of spontaneous birth in the study groups was compared using log-rank tests and hazard ratios.

RESULTS

The study population comprised 10,820 cases with delivery after spontaneous onset of labor among the 16,451 cases who participated in the Screening programme for pre-eclampsia trial. There were 9795 cases in group 1, 583 in group 2, and 442 in group 3. The gestational age at delivery was <28, <32, <35, <37, and <40 weeks in 0.29%, 0.64%, 1.68%, 4.52%, and 44.97% of cases, respectively, in group 1; 0.69%, 1.71%, 3.26%, 7.72%, and 55.23% of cases, respectively, in group 2; and 0.45%, 1.81%, 5.66%, 13.80%, and 63.12% of cases, respectively, in group 3. The curve profile of gestational age at spontaneous birth in the 3 study groups was significantly different overall and in pairwise comparisons (P values <.001). The Cox regression analysis showed that risks increased for spontaneous birth by 18% when the intermediate-risk group was compared with the low-risk group (P˂.001) and by 41% when the high-risk group was compared with the low-risk group (P˂.001).

CONCLUSION

In this study that investigated birth after spontaneous onset of labor in women without preeclampsia, there were 2 major findings. First, the duration of pregnancy decreased with increasing first-trimester risk for preeclampsia. Second, in the high-risk group, when compared with the low-risk group, the risk for spontaneous birth was 4 times higher at a gestational age of 24 to 26 weeks, 3 times higher at 28 to 32 weeks, and 2 times higher at 34 to 39 weeks. These differences present major clinical implications for antepartum counselling, monitoring, and interventions in these pregnancies.

Unique risk factors for unplanned preterm delivery in the uterus transplant recipient

STUDY QUESTION

Do characteristics of the lower uterine segment and cervix modify the risk of preterm delivery in uterus transplant (UTx) recipients?

SUMMARY ANSWER

The cervical length showed little association with preterm delivery, however, cervical inflammation deserves further exploration as a cause of preterm delivery.

WHAT IS KNOWN ALREADY

UTx recipients do not have the risk factors normally used to stratify pregnancies that would benefit from cervical length assessment. In addition, unique factors related to absent tissues, a different blood supply, inflammatory processes of rejection, cervical biopsies, and a different microbiome challenge the normal progressive remodeling of the cervix and thus cervical competence.

STUDY DESIGN, SIZE, DURATION

This is a subanalysis of a clinical trial of 20 women undergoing uterus transplantation at Baylor University Medical Center from 2016 to 2020, in addition to two women who received transplantation outside of a research protocol at our institution through September 2022. In this report, the first 16 UTx recipients that achieved live birth are included.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The focus of this study was 20 pregnancies that reached the second trimester in 16 women following UTx. We analyzed recipient, transplant, and donor factors to determine if characteristics were associated with delivery outcome. We compared obstetrical outcomes, including planned versus unplanned delivery, by factors such as number of superior venous anastomoses, warm ischemia and cold ischemia times, donor factors including cesarean sections, cervical biopsy results, and cervical ultrasound results.

MAIN RESULTS AND THE ROLE OF CHANCE

Planned term deliveries occurred in 44% (8/18) of live births. Of the preterm births, 30% (3/10) were planned and 70% (7/10) were unplanned. Unplanned deliveries occurred in women with spontaneous preterm labor, severe rejection, subchorionic hematoma, and placenta previa. Cervical length in UTx recipients averaged 33.5 mm at 24 weeks and 31.5 mm at 28 weeks, comparable to values from the general population. No relationship was seen between delivery outcome and number of veins used, ischemic time, or number of previous cesarean sections.

LIMITATIONS, REASONS FOR CAUTION

The study's small size allows limited conclusions. The obstetric history of all donors was limited to mode of delivery.

WIDER IMPLICATIONS OF THE FINDINGS

Cervical length measurements in the UTx population are not expected to deviate from those with a native uterus. While cervical length surveillance remains important, attention must be paid to the results of cervical biopsies which are obtained to monitor rejection. Inflammatory processes seem most predictive of preterm delivery.

STUDY FUNDING/COMPETING INTEREST(S)

No funding was provided for this study. The authors report no conflicts of interest.

TRIAL REGISTRATION NUMBER

NCT02656550.

Adverse pregnancy outcomes in women at increased risk of preterm pre-eclampsia on first-trimester combined screening

OBJECTIVE

Uteroplacental dysfunction may not only result in pre-eclampsia (PE) but also in preterm birth (PTB), small-for-gestational-age (SGA) birth and stillbirth. The aim of this study is to evaluate the positive predictive value (PPV) of first-trimester combined PE screening for all of these placenta-mediated adverse pregnancy outcomes.

DESIGN

Retrospective cohort study.

SETTING

Tertiary referral maternity unit.

SAMPLE

A total of 13 211 singleton pregnancies.

METHODS

First-trimester combined screening for preterm PE using the Fetal Medicine Foundation (FMF) algorithm.

MAIN OUTCOMES MEASURES

Hypertensive disorders of pregnancy (HDP), PTB, SGA birth and stillbirth were combined to assess composite adverse and severe adverse pregnancy outcomes (CAPO and CAPO-S). The PPVs for CAPO and CAPO-S were calculated for women with a combined risk for preterm PE of ≥1 in 50 and ≥1 in 100.

RESULTS

First-trimester combined screening identified 2215 women (16.8%) with a risk of ≥1 in 100 for preterm PE. The PPVs for a risk of ≥1 in 100 for CAPO and CAPO-S were 38.8% and 18.2%, respectively. The equivalent PPVs for a risk of ≥1 in 50 were 45.1% and 21.1%, respectively.

CONCLUSIONS

Women identified at high risk of preterm PE are also at increased risk of other placenta-mediated adverse pregnancy outcomes, such as PTB, SGA birth and stillbirth. Women at high risk for preterm PE after first-trimester screening may benefit from a higher surveillance care pathway, with interventions to mitigate all the adverse outcomes associated with placental dysfunction.

Low-dose aspirin and racial disparities in spontaneous preterm delivery in low-risk individuals

BACKGROUND

Preterm birth is a leading cause of perinatal morbidity and mortality. There are significant racial disparities in the rates of preterm delivery in the United States, with Black individuals at disproportionately higher risk than their White counterparts. Although low-dose aspirin is currently under investigation for reducing the rates of preterm delivery, limited data are available on how the use of low-dose aspirin might affect racial and ethnic disparities in the rates of preterm delivery.

OBJECTIVE

Our group and others have shown that low-dose aspirin decreases spontaneous preterm delivery in low-risk parturients. This study aimed to examine whether the relationship between low-dose aspirin and the risk of spontaneous preterm delivery is modified by race and ethnicity.

STUDY DESIGN

This was a secondary analysis of a randomized clinical trial examining low-dose aspirin for preeclampsia prevention in low-risk nulliparous individuals. The parent trial defined low risk as the absence of preexisting hypertension or other medical comorbidities. Participants received 60-mg aspirin or placebo between 13 and 25 weeks of gestation. Here, multiple pregnancies, fetal anomalies, terminations or abortions at <20 weeks of gestation, and participants with previous miscarriages were excluded. Our exposure, race and ethnicity, was self-reported in the parent trial and categorized as non-Hispanic White, Hispanic, non-Hispanic Black, and other. The primary outcome was spontaneous preterm delivery at <34 weeks of gestation; the secondary outcomes included spontaneous preterm delivery at <37 weeks of gestation and all preterm deliveries at <34 and <37 weeks of gestation. Fit logistic regression models were used to examine how the use of low-dose aspirin modified the relationship between race and ethnicity and preterm delivery, adjusting for confounders. Furthermore, sensitivity analyses were performed to compare the rates of preterm delivery by race and ethnicity.

RESULTS

Of note, 2528 of 3171 parent study participants were included in this analysis. Of the participants, 425 (16.8%) were White, 819 (32.4%) were Hispanic, 1265 (50%) were Black, and 19 (0.8%) were other. The baseline characteristics differed among racial and ethnic groups, including maternal age, body mass index, education level, marital status, tobacco and alcohol use, and pregnancy loss. The rate of spontaneous preterm delivery at <34 weeks of gestation was significantly higher in Black participants (2.8%) than in White (1.2%) and Hispanic (1.2%) participants (P=.04). Logistical regression analysis showed that Black race was no longer an independent risk factor for spontaneous preterm delivery at <34 weeks of gestation when controlling for low-dose aspirin (adjusted odds ratio, 1.71; 95% confidence interval, 0.67-4.40). A similar pattern was found for spontaneous preterm delivery at <37 weeks of gestation and preterm delivery at <34 and <37 weeks of gestation. In our sensitivity analyses, spontaneous preterm delivery at <34 weeks of gestation differed by race and ethnicity in the placebo group (P=.01) but did not differ in the low-dose aspirin group (P=.90).

CONCLUSION

The use of low-dose aspirin mitigated racial disparities in spontaneous preterm delivery at <34 weeks of gestation. Additional investigation is warranted to assess the reproducibility of our findings.

Vaginal progesterone for the prevention of recurrent spontaneous preterm birth

After the United States Food and Drug Administration pulled 17-alpha hydroxyprogesterone caproate from the market for its use in prevention of recurrent spontaneous preterm birth, national societies have had mixed recommendations regarding the management of patients with a singleton pregnancy and previous spontaneous preterm birth. Herein we highlight the randomized trial data and translational evidence supporting the use of vaginal progesterone for prevention of recurrent spontaneous preterm birth in singleton pregnancies. Prophylactic vaginal progesterone starting at 16 weeks and 0 days every night should be offered to patients with singletons and previous singleton spontaneous preterm birth regardless of cervical length, and continued along with placement of cerclage if a transvaginal ultrasound cervical length ≤25 mm is detected at <24 weeks.

The Role of Acetylsalicylic Acid in the Prevention of Pre-Eclampsia, Fetal Growth Restriction, and Preterm Birth

BACKGROUND

Recent studies suggest that low-dose acetylsalicylic acid (ASA) can lower pregnancy-associated morbidity.

METHODS

This review is based on pertinent publications that were retrieved by a selective search in PubMed, with special attention to systematic reviews, metaanalyses, and randomized controlled trials.

RESULTS

Current meta-analyses document a reduction of the risk of the occurrence of pre-eclampsia (RR 0.85, NNT 50), as well as beneficial effects on the rates of preterm birth (RR 0.80, NNT 37), fetal growth restriction (RR 0.82, NNT 77), and perinatal death (RR 0.79, NNT 167). Moreover, there is evidence that ASA raises the rate of live births after a prior spontaneous abortion, while also lowering the rate of spontaneous preterm births (RR 0.89, NNT 67). The prerequisites for therapeutic success are an adequate ASA dose, early initiation of ASA, and the identification of women at risk of pregnancy-associated morbidity. Side effects of treatment with ASA in this patient group are rare and mainly involve bleeding in connection with the pregnancy (RR 0.87, NNH 200).

CONCLUSION

ASA use during pregnancy has benefits beyond reducing the risk of pre-eclampsia. The indications for taking ASA during pregnancy may be extended at some point in the future; at present, in view of the available evidence, it is still restricted to high-risk pregnancies.

Prediction and Prevention of Preterm Birth: Secondary Analysis of a Randomized Intervention Trial

Our objective was to evaluate whether pregnancy is prolonged by the use of a proteomics-based maternal serum screening test followed by treatment interventions. This is a secondary analysis of the PREVENT-PTB randomized trial comparing screening with the PreTRM test versus no screening. The primary trial analysis found no significant between-group difference in the preterm birth rate. Rather than considering a dichotomous outcome (preterm versus term), we treated gestational age at birth as a continuous variable using survival analysis. We also evaluated between-group difference in NICU length of stay and duration of respiratory support. Results indicated that pregnancy was significantly prolonged in subjects screened with the PreTRM test compared to controls (adjusted hazard ratio 0.53, 95% confidence interval 0.36-0.78, p < 0.01). Newborns of screened subjects had significantly shorter NICU stays but no significant decrease in duration of respiratory support. In the PreTRM screen-positive group, interventions that were associated with pregnancy prolongation included care management and low-dose aspirin but not 17-hydroxyprogesterone caproate. We conclude that screening with the PreTRM test followed by interventions for screen-positive pregnancies may prolong pregnancy and reduce NICU LOS, but these observations need to be confirmed by additional research.

Progesterone, cerclage, pessary, or acetylsalicylic acid for prevention of preterm birth in singleton and multifetal pregnancies - A systematic review and meta-analyses

Background

Preterm birth is the leading cause of childhood mortality and morbidity. We aimed to provide a comprehensive systematic review on randomized controlled trials (RCTs) on progesterone, cerclage, pessary, and acetylsalicylic acid (ASA) to prevent preterm birth in asymptomatic women with singleton pregnancies defined as risk of preterm birth and multifetal pregnancies.

Methods

Six databases (including PubMed, Embase, Medline, the Cochrane Library) were searched up to February 2022. RCTs published in English or Scandinavian languages were included through a consensus process. Abstracts and duplicates were excluded. The trials were critically appraised by pairs of reviewers. The Cochrane risk-of-bias tool was used for risk of bias assessment. Predefined outcomes including preterm birth, perinatal/neonatal/maternal mortality and morbidity, were pooled in meta-analyses using RevMan 5.4, stratified for high and low risk of bias trials. The certainty of evidence was assessed using the GRADE approach. The systematic review followed the PRISMA guideline.

Results

The search identified 2,309 articles, of which 87 were included in the assessment: 71 original RCTs and 16 secondary publications with 23,886 women and 32,893 offspring. Conclusions were based solely on trials with low risk of bias (n = 50).Singleton pregnancies: Progesterone compared with placebo, reduced the risk of preterm birth <37 gestational weeks: 26.8% vs. 30.2% (Risk Ratio [RR] 0.82 [95% Confidence Interval [CI] 0.71 to 0.95]) (high certainty of evidence, 14 trials) thereby reducing neonatal mortality and respiratory distress syndrome. Cerclage probably reduced the risk of preterm birth <37 gestational weeks: 29.0% vs. 37.6% (RR 0.78 [95% CI 0.69 to 0.88]) (moderate certainty of evidence, four open trials). In addition, perinatal mortality may be reduced by cerclage. Pessary did not demonstrate any overall effect. ASA did not affect any outcome, but evidence was based on one underpowered study.Multifetal pregnancies: The effect of progesterone, cerclage, or pessary was minimal, if any. No study supported improved long-term outcome of the children.

Conclusion

Progesterone and probably also cerclage have a protective effect against preterm birth in asymptomatic women with a singleton pregnancy at risk of preterm birth. Further trials of ASA are needed. Prevention of preterm birth requires screening programs to identify women at risk of preterm birth.

Systematic Review Registration

[https://www.crd.york.ac.uk/prospero/], identifier [CRD42021234946].