Vaginal bleeding in early pregnancy and preterm birth: systemic review and analysis of heterogeneity

Recent Advances and Challenges in the Early Diagnosis and Treatment of Preterm Labor

Preterm birth (PTB) is the primary cause of neonatal mortality and long-term disabilities. The unknown mechanism behind PTB makes diagnosis difficult, yet early detection is necessary for controlling and averting related consequences. The primary focus of this work is to provide an overview of the known risk factors associated with preterm labor and the conventional and advanced procedures for early detection of PTB, including multi-omics and artificial intelligence/machine learning (AI/ML)- based approaches. It also discusses the principles of detecting various proteomic biomarkers based on lateral flow immunoassay and microfluidic chips, along with the commercially available point-of-care testing (POCT) devices and associated challenges. After briefing the therapeutic and preventive measures of PTB, this review summarizes with an outlook.

Determinants of low birth weight among newborns delivered in China: a prospective nested case-control study in a mother and infant cohort

This nested case-control study aimed to investigate the determinants of low birth weight among newborn babies delivered in Shenzhen, Guangdong, China. We recorded socio-demographic data, health status before pregnancy, pregnancy outcomes and complications in a Shenzhen mother and infant cohort. Among 8951 cases, 401 (4.48%) had low birth weight and 1.65% were full-term with LBW. Maternal body mass index, family income, history of pregnancy, hypertension before pregnancy, vaginal bleeding in 1^st trimester, pregnancy-related diabetes, hypertension, placenta previa, placental abruption, premature rupture of membrane, oligohydramnios, and placental types were significantly associated with low birth weight (P < 0.05). In this study, high-risk and mainly preventable factors were linked to low birth weight. Adequate antenatal care, proper maternal nutrition and implementation of proven strategies to prevent high-risk factors may be effective ways to reduce the incidence of low birth weight.

Decreased level of TREM like Transcript 1 (TLT-1) is associated with prematurity and promotes the in-utero inflammatory response to maternal lipopolysaccharide (LPS) exposure

PROBLEM

The occurrence of preterm birth is associated with multiple factors including bleeding, infection and inflammation. Platelets are mediators of hemostasis and can modulate inflammation through interactions with leukocytes. TREM like Transcript 1 (TLT-1) is a type 1 single Ig domain receptor on activated platelets. In adults, it plays a protective role by dampening the inflammatory response and facilitating platelet aggregation at sites of vascular injury. TLT-1 is expressed in human placenta and found in cord blood. We thus hypothesized that TLT-1 deficiency is associated with prematurity and fetal inflammation.

METHOD OF STUDY

To test this hypothesis, we examined cord blood levels of soluble TLT-1 (sTLT) in premature and term infants and compared the inflammatory response in C57BL/6 (WT) and TLT-1-/- (treml1-/- , KO) mice given intraperitoneal LPS mid-gestation RESULTS: The preterm infant cord blood level of sTLT was significantly lower than that found at term. On exposure to LPS, histology of KO (as compared to WT) placenta and decidua showed increased hemorrhage, and KO decidual RNA expression of IL-10 was significantly lower. KO fetal interface tissues (placenta, membranes, amniotic fluid) over time showed increased expression of inflammatory cytokines such as IL-6, IFN-γ, and TNF, but not MCP-1. However, fetal organs showed similar levels.

CONCLUSION

There is a potential association between insufficient TLT-1 expression and increased fetal inflammatory responses in the setting of prematurity. The data support further study of TLT-1 in the mechanistic link between bleeding, inflammation and preterm birth, and perhaps as a biomarker in human pregnancy.

Prevalence and predictors of spontaneous preterm births in Nepal: findings from a prospective, population-based pregnancy cohort in rural Nepal-a secondary data analysis

OBJECTIVE

Preterm birth can have short-term and long-term complications for a child. Socioeconomic factors and pregnancy-related morbidities may be important to predict and prevent preterm births in low-resource settings. The objective of our study was to find prevalence and predictors of spontaneous preterm birth in rural Nepal.

DESIGN

This is a secondary observational analysis of trial data (registration number NCT01177111).

SETTING

Rural Sarlahi district, Nepal.

PARTICIPANTS

40 119 pregnant women enrolled from 9 September 2010 to 16 January 2017.

OUTCOME MEASURES

The outcome variable is spontaneous preterm birth. Generalized Estimating Equations Poisson regression with robust variance was fitted to present effect estimates as risk ratios.

RESULT

The prevalence of spontaneous preterm birth was 14.5% (0.5% non-spontaneous). Characteristics not varying in pregnancy associated with increased risk of preterm birth were maternal age less than 18 years (adjusted risk ratio=1.13, 95% CI: 1.02 to 1.26); being Muslim (1.53, 1.16 to 2.01); first pregnancy (1.15, 1.04 to 1.28); multiple births (4.91, 4.20 to 5.75) and male child (1.10, 1.02 to 1.17). Those associated with decreased risk were maternal education >5 years (0.81, 0.73 to 0.90); maternal height ≥150 cm (0.89, 0.81 to 0.98) and being from wealthier families (0.83, 0.74 to 0.93). Pregnancy-related morbidities associated with increased risk of preterm birth were vaginal bleeding (1.53, 1.08 to 2.18); swelling (1.37, 1.17 to 1.60); high systolic blood pressure (BP) (1.47, 1.08 to 2.01) and high diastolic BP (1.41, 1.17 to 1.70) in the third trimester. Those associated with decreased risk were respiratory problem in the third trimester (0.86, 0.79 to 0.94); having poor appetite, nausea and vomiting in the second trimester (0.86, 0.80 to 0.92) and third trimester (0.86, 0.79 to 0.94); and higher weight gain from second to third trimester (0.89, 0.87 to 0.90).

CONCLUSION

The prevalence of preterm birth is high in rural Nepal. Interventions that increase maternal education may play a role. Monitoring morbidities during antenatal care to intervene to reduce them through an effective health system may help reduce preterm birth.

Preterm delivery and its associated factors among mothers in Bangladesh: survey in Rajshahi district

OBJECTIVES

Preterm delivery (PD) is a worldwide health burden particularly in low-income and middle-income countries such as Bangladesh. It is a key indicator of neonatal mortality and a risk of morbidity in later life. This study aimed to determine the prevalence of PD and its associated factors among mothers in Northern region of Bangladesh.

SETTING AND PARTICIPANTS

Multistage sampling technique was used to select samples covering all the population from 9 Upazilas in Rajshahi district with 233 community clinics. A total of 540 mothers and their under-5 children were enrolled for the study. Descriptive statistics, χ² test and logistic regression model were used to analyse the data.

RESULTS

Among all live births, the prevalence of PD was found to be 14.6%. Multiple binary logistic regression model suggested five factors of PD: (1) mothers who used contraceptive pill had lower chance of PD (p<0.05); (2) mothers with high fever during pregnancy period were more likely to have PD (p<0.05); (3) mothers who did not receive antenatal care service less than four times during pregnancy period had higher chance of PD (p<0.01); (4) mothers first married before 18 years who were more likely to have PD (p<0.01); (5) PD delivered mothers had more chance to get low birth weight children (p<0.05). In addition, unadjusted model demonstrated that mothers delivered first baby before their age<20 years were more risk to get PD (p<0.05).

CONCLUSION

Approximately one in seven infants was born preterm in our study area. Family planning method, number of antenatal care visit, mothers' age at marriage and high fever during pregnancy were the most important predictors of PD, these factors could be considered to reduce PD among Bangladeshi mothers. PD risk could be reduced by counselling and encouraging women to take antenatal care facilities from trained health providers.

Study on the correlation between vaginal bleeding in first trimester and preterm birth: A birth cohort study in Lanzhou, China

OBJECTS

To investigate the correlation between first trimester vaginal bleeding and preterm birth (PB), and to offer suggestions on the perinatal health care and preterm birth prevention.

METHODS

A birth cohort study was conducted on 10 179 pregnant women. Unconditional logistic regression model was used to evaluate the associations between vaginal bleeding and preterm birth in sub-preterm groups.

RESULTS

Of the 10 179 pregnant women included, a total of 1001 women suffered from vaginal bleeding during the first trimester, of which 119 suffered from PB. Any vaginal bleeding increased the risk of PB. Severe bleeding was a high-risk factor of PB, associated with 4.8-fold risk of very PB, 2.7-fold risk of spontaneous PB without PROM (premature rupture of membrane) and 4.6-fold risk of medical induced PB. Bleeding prolonged more than 1 week increased 66% risk of PB and 36% risk of PB on initial episode happened in 5-12 weeks of gestation age, especially in moderate PB, in medical-induced PB and in spontaneous PB with PPROM (preterm premature rupture of membrane which is one cause of PB). Mild bleeding or bleeding within 1 week or initial episode happened within 4 weeks of gestation age possibly had no influence on PB.

CONCLUSION

Vaginal bleeding in the first-trimester was an independent risk factor for PB. The severity, duration and initial time of vaginal bleeding had different effects on different subtypes of PB.

Association between antenatal care visit and preterm birth: a cohort study in rural Bangladesh

BACKGROUND

Strengthening the antenatal care programme is suggested as one of the public health strategies to reduce preterm birth burden at a population level. However, the evidence so far available is inconclusive.

OBJECTIVES

To evaluate the association between antenatal care (ANC) visit and preterm birth; and also to explore to what extent the increased usage of ANC after the initiation of the Maternal, Neonatal and Child Health (MNCH) project in Matlab, Bangladesh, contributed to the reduction of preterm birth.

SETTING

This population-based cohort study was conducted in Matlab, a subdistrict under Chandpur. The analysis was based on data collected from 2005 to 2009. In 2007, an MNCH project was initiated in the area that strengthened the ongoing ANC services.

PARTICIPANTS

In total, 12 980 live births with their mothers during the study period were included in the analysis.

ANALYSIS

We performed logistic regression with generalised estimating equation models to evaluate the associations.

OUTCOME MEASURES

Preterm birth.

RESULTS

The number of ANC visits was associated with preterm birth in a dose-dependent way (p for linear trend <0.001). The adjusted odds of preterm birth were 2.4-times higher (OR 2.37, 95% CI 2.07 to 2.70) among women who received ≤1 ANC compared with women who received ≥3 ANC. We observed a significant reduction of preterm birth rates (OR 0.69, 95% CI 0.61 to 0.77) in the period after (2008 to 2009) MNCH project initiation in comparison to the period before (2005 to 2006). Controlling for ANC visits substantially attenuated this observed effect of the MNCH project on preterm birth (OR 0.88, 95% CI 0.77 to 0.99) (Sobel test of mediation p<0.001).

CONCLUSIONS

ANC visits are associated with decreased occurrences of preterm births. Strengthening the ANC services should be prioritised in countries with high preterm birth rates to reduce the preterm birth burden at the population level.

Obstetric outcomes of twin pregnancies presenting with a complete hydatidiform mole and coexistent normal fetus: a systematic review and meta-analysis

BACKGROUND

Epidemiological data on obstetric and oncologic complications in twin pregnancies combining a complete hydatidiform mole (CHM) coexisting with a normal fetus and placenta are limited.

OBJECTIVES

To evaluate perinatal and obstetric outcomes for mother and fetus and risk of gestational trophoblastic neoplasia (GTN) in twin pregnancies including a CHM.

SEARCH STRATEGY

PubMed, MEDLINE and EMBASE and the grey literature were searched for articles published between May 1980 and May 2019 using a protocol designed a priori and registered on PROSPERO (CRD42018112524).

SELECTION CRITERIA

Observational cohort studies of four or more cases confirmed by histopathology and providing data on pregnancy outcomes and GTN.

DATA COLLECTION AND ANALYSIS

Two reviewers independently reviewed abstracts and full-text articles. The quality of the studies was assessed with the Newcastle-Ottawa scale and a meta-analysis was performed.

MAIN RESULTS

Of the 344 abstracts identified, 14 studies (244 cases) met the eligibility criteria. The incidence of maternal complication in ongoing pregnancies was 80.8% and included vaginal bleeding, hyperthyroidism and pre-eclampsia. There were overall 91 (50%) live births in ongoing pregnancies and 83 (34%) of the total cases were subsequently diagnosed with GTN. Substantial and significant (P < 0.001) heterogeneity was found for the incidence of preeclampsia indicating variability in reporting the incidence of some obstetric complications between studies.

CONCLUSIONS

Patients diagnosed with a twin pregnancy combining a CHM and an apparently normal fetus have a high risk of perinatal complications, low live-birth rates and around a third of them will develop a GTN and should be managed by specialised multidisciplinary teams.

TWEETABLE ABSTRACT

Our study indicates a high rate of obstetric and oncologic complications in patients presenting with a complete hydatidiform mole and coexistent normal fetus.

Pathophysiology of preterm labor with intact membranes

Preterm labor with intact membranes is a major cause of spontaneous preterm birth (sPTB). To prevent sPTB a clear understanding is needed of the hormonal interactions that initiate labor. The steroid hormone progesterone acting via its nuclear progesterone receptors (PRs) in uterine cells is essential for the establishment and maintenance of pregnancy and disruption of PR signaling (i.e., functional progesterone/PR withdrawal) is key trigger for labor. The process of parturition is also associated with inflammation within the uterine tissues and it is now generally accepted that inflammatory stimuli from multiple extrinsic and intrinsic sources induce labor. Recent studies suggest inflammatory stimuli induce labor by affecting PR transcriptional activity in uterine cells to cause functional progesterone/PR withdrawal. Advances in understanding the functional interaction of inflammatory load on the pregnancy uterus and progesterone/PR signaling is opening novel areas of research and may lead to rational therapeutic strategies to effectively prevent sPTB.

Vaginal bleeding in early pregnancy and circulating markers of thrombin generation

OBJECTIVE

To determine if subjects experiencing acute vaginal bleeding in early pregnancy have increased plasma markers of thrombin generation compared to nonbleeding controls.

METHODS

Subjects with clinically apparent acute (within 24 h of sample collection) vaginal bleeding between 6 and 20 weeks estimated gestational age and without known thrombophilias were enrolled, along with nonbleeding controls, and underwent collection of maternal plasma. Concentrations of thrombin-antithrombin (TAT) and fragment 1 + 2 (F1 + 2) were determined by enzyme-linked immunosorbent assay. Differences between bleeding and nonbleeding subjects were assessed through linear regression with adjustment for gestational age.

RESULTS

Twenty subjects with vaginal bleeding and 20 controls were included. Bleeding was significantly associated with increased concentrations of TAT (p = 0.007) and F1 + 2 (p = 0.044) when corrected for gestational age. Among bleeding subjects, there was no association between markers of thrombin generation and the subject's description of bleeding quantity, though higher concentrations were associated with a longer self-reported duration of bleeding.

CONCLUSIONS

Clinically apparent vaginal bleeding in early pregnancy is associated with increased circulating maternal markers of thrombin generation. Thus, these maternal markers may have a future role in risk stratification.