Previous pregnancy loss: risks related to severity of preterm delivery

Obstetric and perinatal outcomes of women with a history of recurrent pregnancy loss: a meta-analysis of cohort studies

PURPOSE

To assess the risk of adverse obstetric and perinatal outcomes in subsequent pregnancies among women with a history of recurrent pregnancy loss (RPL).

METHODS

Relevant studies were identified by searching the PubMed, Web of Science, and Embase databases. The pooled effect sizes were reported as odds ratios (OR) with their respective 95% confidence intervals (95% CI), and data analysis was performed using the random effects model.

RESULTS

A total of 26 studies involving 4,730,728 women were included in this meta-analysis. The results reveal a significant increase in the prevalence of placenta accreta cases after RPL compared to women without RPL (pooled OR 4.04; 95% CI 1.16-14.15; 2 studies; I2 = 94%; P = 0.03). However, no elevated risk of aneuploidies (pooled OR 1.69, 95% CI 0.73-3.90; 5 studies; I2 = 48%; P = 0.22) or congenital anomalies (pooled OR 1.12, 95% CI 0.97-1.30; 7 studies; I2 = 13%; P = 0.12) in subsequent pregnancies of women with RPL was observed. Additionally, a moderate increase in the risk of various other obstetric and perinatal outcomes was found. The magnitude of the elevated risk of these adverse outcomes varied depending on the region.

CONCLUSIONS

Women with a history of RPL exhibit a significantly elevated risk of placenta accreta in subsequent pregnancies, along with a moderate increase in the risk of various other adverse obstetric and perinatal outcomes. However, RPL does not signify an increased risk of aneuploidies or congenital anomalies in a consecutive pregnancy.

Antepartum Intimate Partner Violence: Development of a Risk Prediction Model

Objectives: To explore socio-behavioral, clinical, and imaging findings associated with antepartum intimate partner violence (IPV) and aid in risk stratification of at-risk individuals. Methods: We analyzed electronic medical records during indexed pregnancies for 108 pregnant patients who self-reported antepartum IPV (cases) and 106 age-matched pregnant patients who did not self-report antepartum IPV (controls). Sociodemographic, clinical, and radiology data were analyzed via chi-squared and Fisher's exact tests with p < 0.05 as the threshold for significance. Stepwise logistic regression was applied to derive a risk prediction model. Results: The proportion of cases reporting emotional IPV (76% vs. 52%) and/or physical IPV (45% vs. 31%) during pregnancy significantly increased from prior to pregnancy. Cases were significantly more likely to report prepregnancy substance use (odds ratio [OR] = 2.60; 95% confidence interval [CI]: 1.13-5.98), sexually transmitted infections (OR = 3.48; 95%CI: 1.64-7.37), abortion (OR = 3.17; 95%CI: 1.79, 5.59), and preterm birth (OR = 5.97; 95%CI: 1.69-21.15). During pregnancy, cases were more likely to report unstable housing (OR = 5.26; 95%CI: 2.67-10.36), multigravidity (OR = 2.83; 95%CI: 1.44-5.58), multiparity (OR = 3.75; 95%CI: 1.72-8.20), anxiety (OR = 3.35; 95%CI: 1.85-6.08), depression (OR = 5.58; 95%CI: 3.07-10.16), substance use (OR = 2.92; 95%CI: 1.28-6.65), urinary tract infection (UTI) (OR = 3.26; 95%CI: 1.14-9.32), intrauterine growth restriction (OR = 10.71; 95%CI: 1.35-85.25), and cesarean delivery (OR = 2.25; 95%CI: 1.26-4.02). Cases had significantly more OBGYN abnormalities on imaging and canceled more radiological studies (OR = 5.31). Logistic regression found housing status, sexually transmitted infection history, preterm delivery history, abortion history, depression, and antepartum UTI predictive of antepartum IPV. The risk prediction model achieved good calibration with an area under the curve of 0.79. Conclusions: This study identifies significant disparities among patients experiencing antepartum IPV, and our proposed risk prediction model can inform risk assessment in this setting.

Prevalence of preterm birth in Scandinavian countries: a systematic review and meta-analysis

OBJECTIVES

As welfare societies, Scandinavian countries share characteristics of equality related to healthcare access, gender, and social services. However, cultural and lifestyle variations create country-specific health differences. This meta-analysis assessed the prevalence of preterm birth (PTB) and its categories in Scandinavian countries.

METHODS

A systematic search in key databases of literature published between 1990 and 2021 identified studies of the prevalence of PTB and its categories. Following the use of the Freeman-Tukey double arcsine transformation, a meta-analysis of weighted data was performed using the random-effects model and meta-prop method.

RESULTS

We identified 109 observational studies that involved 86,420,188 live births. The overall pooled prevalence (PP) of PTB was 5.3% (PP = 5.3%, 95% confidence interval [CI] 5.1%, 5.5%). The highest prevalence was in Norway (PP = 6.2%, 95% CI 5.3%, 7.0%), followed by Sweden (PP = 5.3%, 95% CI 5.1%, 5.4%), Denmark (PP = 5.2%, 95% CI 4.9%, 5.3%), and Iceland (PP = 5.0%, 95% CI 4.4%, 5.7%). Finland had the lowest PTB rate (PP = 4.9%, 95% CI 4.7%, 5.1%).

CONCLUSIONS

The overall PP of PTB was 5.3%, with small variations among countries (4.9%-6.2%). The highest and lowest PPs of PTB were in Norway and Finland, respectively.

Adverse obstetric and perinatal outcomes of patients with history of recurrent miscarriage: a retrospective cohort study

OBJECTIVE

To examine the associations between a history of recurrent miscarriage (RM) and adverse obstetric and perinatal outcomes in the subsequent pregnancy that progressed beyond 24 weeks.

DESIGN

Retrospective cohort study.

SETTING

A large tertiary maternity hospital.

PATIENT(S)

All women who booked for antenatal care and delivery between January 2014 and August 2021 were recorded. The study was limited to women with a singleton pregnancy, and to avoid intraperson correlation, we selected the first record of delivery from each mother in the study, leaving 108,792 deliveries for analysis. Obstetric and perinatal outcomes were compared among 1994 women (1.83%) with a history of ≥2 miscarriages (RM), 11,477 women (10.55%) with a history of 1 miscarriage, and 95,321 women (87.62%) with no history of miscarriage, respectively.

INTERVENTION(S)

Women with a history of ≥2 miscarriages or RM.

MAIN OUTCOME MEASURE(S)

Obstetric complications included gestational diabetes mellitus, preeclampsia (subclassified as preterm and term preeclampsia), placenta previa, placenta accreta, and fetal distress. Perinatal outcomes included emergency cesarean section, elective cesarean section, induction, postpartum hemorrhage, preterm birth, stillbirth, Apgar score <7 at 5 minutes, neonatal asphyxia, neonatal sex, congenital; malformation, low birth weight, and neonatal death.

RESULT(S)

After adjusting for relevant confounders, there was an increased risk of adverse obstetric and perinatal outcomes in a subsequent pregnancy for women with a history of RM, specifically for placental dysfunction disorders: preterm preeclampsia (risk ratio [RR] = 1.58; 95% confidence interval [CI], 1.03-2.32), preterm birth (RR = 1.34; 95% CI, 1.15-1.54)], and abnormal placentation, that is placenta previa (RR = 1.78; 95% CI, 1.36-2.28), and placenta accreta (RR = 4.19; 95% CI, 2.75-6.13).

CONCLUSION(S)

Significant associations existed between a history of RM and the occurrence of adverse obstetric and perinatal outcomes including placental dysfunction disorders and abnormal placentation. These findings may contribute to the early detection and appropriate intervention for placenta-associated diseases in women with a history of RM, with the goal of avoiding or reducing the associated detrimental effects.

Residential proximity to pesticide applications in Argentine Patagonia: impact on pregnancy and newborn parameters

Among residents living close to agricultural fields who are potentially exposed to pesticides, pregnant women and their fetuses are of particular concern for their vulnerability to environmental chemicals. In this collaborative multicenter study, we covered a wide distribution of participants in the most important fruit production zone of north Patagonia (Argentina) to investigate whether maternal residential proximity to fruit croplands with intense pesticide applications (rural group -RG-) is associated with pregnancy complications and alterations in their newborn parameters compared to the urban population (urban group -UG-). A total of 776 pregnant women met the inclusion criteria. The percentage of threatened miscarriage was significantly higher in the RG than in the UG. The percentage of miscarriage, threat of premature labor, intrauterine fetal death, preterm premature rupture of membranes, and intrauterine growth retardation were similar in both groups. Newborn anthropometric parameters were corrected by sex and gestational age prior to statistical analysis. Length at birth and head circumference were lower in the RG than in the UG. Birth weight was similar in both groups. The percentage of head circumference less than the 5th percentile and the ponderal index were greater in the RG than in the UG. Our results suggest that proximity to pesticide applications may increase the risk of pregnancy complications and altered newborn parameters.

Characterization of highly proliferative decidual precursor cells during the window of implantation in human endometrium

Pregnancy depends on the wholesale transformation of the endometrium, a process driven by differentiation of endometrial stromal cells (EnSC) into specialist decidual cells. Upon embryo implantation, decidual cells impart the tissue plasticity needed to accommodate a rapidly growing conceptus and invading placenta, although the underlying mechanisms are unclear. Here we characterize a discrete population of highly proliferative mesenchymal cells (hPMC) in midluteal human endometrium, coinciding with the window of embryo implantation. Single-cell transcriptomics demonstrated that hPMC express genes involved in chemotaxis and vascular transmigration. Although distinct from resident EnSC, hPMC also express genes encoding pivotal decidual transcription factors and markers, most prominently prolactin. We further show that hPMC are enriched around spiral arterioles, scattered throughout the stroma, and occasionally present in glandular and luminal epithelium. The abundance of hPMC correlated with the in vitro colony-forming unit activity of midluteal endometrium and, conversely, clonogenic cells in culture express a gene signature partially conserved in hPMC. Cross-referencing of single-cell RNA-sequencing data sets indicated that hPMC differentiate into a recently discovered decidual subpopulation in early pregnancy. Finally, we demonstrate that recurrent pregnancy loss is associated with hPMC depletion. Collectively, our findings characterize midluteal hPMC as novel decidual precursors that are likely derived from circulating bone marrow-derived mesenchymal stem/stromal cells and integral to decidual plasticity in pregnancy.

Long-Term IoT-Based Maternal Monitoring: System Design and Evaluation

Pregnancy is a unique time when many mothers gain awareness of their lifestyle and its impacts on the fetus. High-quality care during pregnancy is needed to identify possible complications early and ensure the mother’s and her unborn baby’s health and well-being. Different studies have thus far proposed maternal health monitoring systems. However, they are designed for a specific health problem or are limited to questionnaires and short-term data collection methods. Moreover, the requirements and challenges have not been evaluated in long-term studies. Maternal health necessitates a comprehensive framework enabling continuous monitoring of pregnant women. In this paper, we present an Internet-of-Things (IoT)-based system to provide ubiquitous maternal health monitoring during pregnancy and postpartum. The system consists of various data collectors to track the mother’s condition, including stress, sleep, and physical activity. We carried out the full system implementation and conducted a real human subject study on pregnant women in Southwestern Finland. We then evaluated the system’s feasibility, energy efficiency, and data reliability. Our results show that the implemented system is feasible in terms of system usage during nine months. We also indicate the smartwatch, used in our study, has acceptable energy efficiency in long-term monitoring and is able to collect reliable photoplethysmography data. Finally, we discuss the integration of the presented system with the current healthcare system.

Factors associated with risk of preterm delivery in Tanzania: A case-control study at Muhimbili National Hospital

OBJECTIVE

To determine factors associated with risk of preterm delivery among pregnant women delivering at Muhimbili National Hospital in Tanzania.

METHODS

A 1:1 case-control study was conducted to assess maternal sociodemographic, lifestyle, and current and previous obstetric factors associated with risk of preterm delivery. Mothers of preterm infants were regarded as cases and those of term infants were controls. Chi-square test and logistic regression were used to assess association between the factors and risk of preterm delivery.

RESULTS

A total of 222 case-control pairs were studied. Maternal type of employment (P = 0.039), previous preterm delivery (P = 0.002), previous spontaneous abortion (P = 0.004), uterine scar (P < 0.001), parity (P = 0.034), number of prenatal care visits (P = 0.032), premature rupture of membranes (PROM) (P < 0.001), placenta previa (P = 0.002), bleeding during second trimester (P = 0.004), pre-eclampsia (P < 0.001), and maternal anemia (P = 0.033) were associated with risk of preterm delivery. The main risk factors associated with preterm delivery included previous preterm delivery (odds ratio [OR] 13.23, 95% confidence interval [CI] 1.72-101.95), placenta previa (OR 12.63, 95% CI 1.63-97.98), and PROM (OR 8.77, 95% CI 1.33-4.60).

CONCLUSION

Close monitoring of pregnant women who present any of the risk factors is important to prevent or reduce the risk of preterm delivery in Tanzania.

Impact of Recurrent Miscarriage on Maternal Outcomes in Subsequent Pregnancy: The Mutaba'ah Study

Purpose

To estimate the prevalence of recurrent miscarriage (RM) and investigate the association between RM and adverse maternal outcomes in subsequent pregnancies.

Participants and Methods

This is an interim analysis of a prospective study of 1737 pregnant women with gravidity of two or more prior to the current pregnancy. These women joined the Mutaba’ah Study between May 2017 and April 2019 and were followed up until they delivered. Hospital medical records were used to extract data on past pregnancy history and the progress and outcomes of the current pregnancy, such as gestational diabetes, preeclampsia, mode of delivery, preterm delivery, and complications at birth.

Results

Amongst pregnant women with at least two previous pregnancies (n=1737), there were 234 (13.5%) women with a history of two or more consecutive miscarriages. Women with RM were slightly older, more parous, and more likely to have had previous infertility treatment (all p-values <0.05). Women with a history of RM had independently significant increased odds of cesarean section (adjusted odds ratio (aOR) 1.81, 95% CI 1.24–2.65) and preterm (<37 weeks, aOR: 2.52, 95% CI 1.56–4.08) or very preterm delivery (<32 weeks, aOR: 7.02 95% CI 2.41–20.46) in subsequent pregnancies than women who did not have a history of RM.

Conclusion

Women with a history of RM were twice as likely to undergo cesarean section and seven times more likely to deliver prior to 32 weeks of gestation than women without a history of RM. The study findings support the need for early pregnancy monitoring or assessment units to ensure better follow-up and customized care for at-risk pregnant women with a history of RM.

Pregnancy decisions after fetal or perinatal death: systematic review of qualitative research

OBJECTIVES

To synthesise the findings of qualitative research exploring parents' experiences, views and decisions about becoming pregnant following a perinatal death or fetal loss.

DESIGN

Systematic review and meta-synthesis of qualitative research.

DATA SOURCES

Medline, Web of Science, CINAHL, PsycINFO, ASSIA, Embase, PUBMED, Scopus and Google Scholar.

ELIGIBILITY CRITERIA

Nine electronic databases were searched using predefined search terms. Articles published in English, in peer-reviewed journals, using qualitative methods to explore the experiences and attitudes of bereaved parents following perinatal or fetal loss, were included.

DATA EXTRACTION AND SYNTHESIS

Qualitative data relating to first-order and second-order constructs were extracted and synthesised across studies using a thematic analysis.

RESULTS

15 studies were included. Four descriptive themes and 10 subthemes were identified. The descriptive themes were: deciding about subsequent pregnancy, diversity of reactions to the event, social network influences, and planning or timing of subsequent pregnancy. The decision to become pregnant after death is complex and varies between individuals and sometimes within couples. Decisions are often made quickly, in the immediate aftermath of a pregnancy loss, but may evolve over time. Bereaved parents may feel isolated from social networks.

CONCLUSIONS

There is an opportunity to support parents to prepare for a pregnancy after a fetal or perinatal loss, and conversations may be welcomed at an early stage. Health professionals may play an important role providing support lacking from usual social networks.

PROSPERO REGISTRATION NUMBER

CRD42018112839.

Subsequent pregnancy outcomes following second trimester miscarriage-A prospective cohort study

OBJECTIVES

Pregnancy after second-trimester miscarriage represents as clinical challenge. This study sought to determine the rates of recurrence, preterm birth and live births in a cohort of 185 women with previous second-trimester miscarriage. We hypothesized that there would be a higher rate of second-trimester miscarriage and preterm birth in subsequent pregnancy after second trimester miscarriage. The primary objectives of this study were to establish rates of second-trimester miscarriage, preterm birth and live births in this cohort. Secondary objectives were to examine medical and surgical interventions, in addition to other pregnancy outcomes and complications.

STUDY DESIGN

This was a prospective cohort study carried out in a tertiary referral center in southern Ireland with over 8000 deliveries per year. 175 women were followed up. Inclusion criteria were an ultrasound confirmed second-trimester miscarriage between June 2009 and June 2013 and subsequently having a pregnancy between July 2009 and January 2016. Fifty-five women did not become pregnant during the study period and were excluded. Ten women were excluded for missing data.

RESULTS

Between July 2009 and January 2016, 110 women became pregnant following a previous second-trimester miscarriage. In total, 81 babies were born to 77 mothers. The recurrence rate of second-trimester miscarriage was 6.3% (7/110) and the preterm birth rate was also 6.3% (7/110). The cesarean section rate was 45%. Including those who experienced first or second trimester miscarriage, 47% (78/155) of those who were followed up did not go on to have a live infant.

CONCLUSIONS

Women experiencing second-trimester miscarriage are at increased risk in subsequent pregnancies of recurrence. Second-trimester miscarriage needs to be highlighted as a risk factor for adverse pregnancy outcomes. Greater research into its pathophysiology is required to advance preventative measures.

Role of maternal age and pregnancy history in risk of miscarriage: prospective register based study

OBJECTIVES

To estimate the burden of miscarriage in the Norwegian population and to evaluate the associations with maternal age and pregnancy history.

DESIGN

Prospective register based study.

SETTING

Medical Birth Register of Norway, the Norwegian Patient Register, and the induced abortion register.

PARTICIPANTS

All Norwegian women that were pregnant between 2009-13.

MAIN OUTCOME MEASURE

Risk of miscarriage according to the woman's age and pregnancy history estimated by logistic regression.

RESULTS

There were 421 201 pregnancies during the study period. The risk of miscarriage was lowest in women aged 25-29 (10%), and rose rapidly after age 30, reaching 53% in women aged 45 and over. There was a strong recurrence risk of miscarriage, with age adjusted odds ratios of 1.54 (95% confidence interval 1.48 to 1.60) after one miscarriage, 2.21 (2.03 to 2.41) after two, and 3.97 (3.29 to 4.78) after three consecutive miscarriages. The risk of miscarriage was modestly increased if the previous birth ended in a preterm delivery (adjusted odds ratio 1.22, 95% confidence interval 1.12 to 1.29), stillbirth (1.30, 1.11 to 1.53), caesarean section (1.16, 1.12 to 1.21), or if the woman had gestational diabetes in the previous pregnancy (1.19, 1.05 to 1.36). The risk of miscarriage was slightly higher in women who themselves had been small for gestational age (1.08, 1.04 to 1.13).

CONCLUSIONS

The risk of miscarriage varies greatly with maternal age, shows a strong pattern of recurrence, and is also increased after some adverse pregnancy outcomes. Miscarriage and other pregnancy complications might share underlying causes, which could be biological conditions or unmeasured common risk factors.

Adverse pregnancy and perinatal outcome in patients with recurrent pregnancy loss: Multiple imputation analyses with propensity score adjustment applied to a large-scale birth cohort of the Japan Environment and Children's Study

PROBLEM

Several studies have reported the increased risk of preterm birth, premature rupture of membranes, and low birth weight in patients with recurrent pregnancy loss (RPL). There have been a limited number of large population-based studies examining adverse pregnancy and perinatal outcome after RPL. Multiple-imputed analyses (MIA) adjusting for biases due to missing data is also lacking.

METHOD OF STUDY

A nationwide birth cohort study known as the "Japan Environment and Children's Study (JECS)" was conducted by the Ministry of the Environment. The subjects consisted of 104 102 registered children (including fetuses or embryos).

RESULTS

No increased risk of a congenital anomaly, aneuploidy, neonatal asphyxia, or a small for date infant was observed among the children from women with a history of RPL. A novel increased risk of placental adhesion and uterine infection was found. The adjusted ORs using MIA in women with three or more PL were 1.76 (95% CI, 1.04-2.96) for a stillbirth, 1.68 (1.12-2.52) for a pregnancy loss, 2.53 (1.17-5.47) for placental adhesion, 1.87 (1.37-2.55) and 1.60 (.99-2.57) for mild and severe hypertensive disorders of pregnancy, respectively, 1.94 (1.06-3.55) for uterine infection, 1.28 (1.11-1.47) for caesarean section and .86 (.76-.98) for a male infant.

CONCLUSION

MIA better quantified the risk, which could encourage women who might hesitate to attempt a subsequent pregnancy.

Acute Impact of Hourly Ambient Air Pollution on Preterm Birth

BACKGROUND

Preterm birth is a major perinatal health problem, but factors leading to it are still not completely understood.

OBJECTIVES

Our goal was to identify the relation between acute increase in ambient air pollution in a few hours before onset of labor and the risk of preterm birth.

METHODS

We collected registered birth outcome data and hourly ambient air pollution measurements during 2009‒2013 in Brisbane, Australia. Using a time-stratified case-crossover design and conditional logistic regression models with natural cubic splines, we assessed the shape of air pollution-preterm birth curve, after controlling for potential confounders. We also examined the effect modification of other factors.

RESULTS

The association between air pollution [nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide (CO)] and preterm birth was nonlinear. Threshold concentrations for the mean of 0‒24 hr NO2, 24‒48 hr SO2, and 24‒48 hr CO before onset of labor were 7.6 parts per billion (ppb), 3.8 ppb, and 162.5 ppb, respectively. Increases in air pollution concentrations above thresholds were associated with increased risks of preterm birth. The odds ratios of preterm birth at the 95th percentile of NO2, SO2, and CO against the thresholds were 1.17 (95% CI: 1.08, 1.27), 1.01 (95% CI: 0.99, 1.04), and 1.18 (95% CI: 1.06, 1.32), respectively. The associations were modified by demographic factors, such as maternal smoking and socioeconomic status.

CONCLUSION

Acute increases in ambient air pollution concentrations above certain levels before onset of labor may stimulate preterm birth.

CITATION

Li S, Guo Y, Williams G. 2016. Acute impact of hourly ambient air pollution on preterm birth. Environ Health Perspect 124:1623-1629; http://dx.doi.org/10.1289/EHP200.

A prospective cohort study of a woman's own gestational age and her fecundability

STUDY QUESTION

What is the magnitude of the association between a woman's gestational age at her own birth and her fecundability (cycle-specific probability of conception)?

SUMMARY ANSWER

We found a 62% decrease in fecundability among women born <34 weeks of gestation relative to women born at 37-41 weeks of gestation, whereas there were few differences in fecundability among women born at later gestational ages.

WHAT IS KNOWN ALREADY

One study, using retrospectively collected data on time-to-pregnancy (TTP), and self-reported data on gestational age, found a prolonged TTP among women born <37 gestational weeks (preterm) and with a birthweight ≤1500 g. Other studies of women's gestational age at birth and subsequent fertility, based on data from national birth registries, have reported a reduced probability of giving birth among women born <32 weeks of gestation.

STUDY DESIGN, SIZE, DURATION

We used data from a prospective cohort study of Danish pregnancy planners ('Snart-Gravid'), enrolled during 2007-2011 and followed until 2012. In all, 2814 women were enrolled in our study, of which 2569 had complete follow-up.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women eligible to participate were 18-40 years old at study entry, in a relationship with a male partner, and attempting to conceive. Participants completed a baseline questionnaire and up to six follow-up questionnaires until the report of pregnancy, discontinuation of pregnancy attempts, beginning of fertility treatment, loss to follow-up or end of study observation after 12 months.

MAIN RESULTS AND THE ROLE OF CHANCE

Among women born <34 gestational weeks, the cumulative probability of conception was 12, 28 and 48% within 3, 6 and 12 cycles, respectively. Among women born at 37-41 weeks of gestation, cumulative probability of conception was 47, 67 and 84% within 3, 6 and 12 cycles, respectively. Relative to women born at 37-41 weeks' gestation, women born <34 weeks had decreased fecundability (fecundability ratio (FR) 0.38, 95% confidence interval (CI): 0.17-0.82). Our data did not suggest reduced fecundability among women born at 34-36 weeks of gestation or at ≥42 weeks of gestation (FR 1.03, 95% CI: 0.80-1.34, and FR 1.13, 95% CI: 0.96-1.33, respectively).

LIMITATIONS, REASONS FOR CAUTION

Data on gestational age, obtained from the Danish Medical Birth Registry, were more likely to be based on date of last menstrual period than early ultrasound examination, possibly leading to an overestimation of gestational age at birth. Such overestimation, however, would not explain the decrease in fecundability observed among women born <34 gestational weeks. Another limitation is that the proportion of women born before 34 weeks of gestation was low in our study population, which reduced the precision of the estimates.

WIDER IMPLICATIONS OF THE FINDINGS

By using prospective data on TTP, our study elaborates on previous reports of impaired fertility among women born preterm, suggesting that women born <34 weeks of gestation have reduced fecundability.

STUDY FUNDING/COMPETING INTERESTS

The study was supported by the National Institute of Child Health and Human Development (R21-050264), the Danish Medical Research Council (271-07-0338), and the Health Research Fund of Central Denmark Region (1-01-72-84-10). The authors have no competing interests to declare.

Reduced levels of plasma kisspeptin during the antenatal booking visit are associated with increased risk of miscarriage

CONTEXT

Kisspeptin is a recently identified hormone encoded by the KISS1 gene, playing a critical role in human reproduction. Plasma kisspeptin levels rise dramatically during normal pregnancy due to placental synthesis, which implicates it as a potential tool for assessing risks of pregnancy complications. No previous prospective study has investigated the association between plasma kisspeptin and risk of miscarriage.

OBJECTIVE

The objective of the study was to determine whether a single plasma kisspeptin or serum human chorionic gonadotropin (hCG) measurement in asymptomatic women attending their booking antenatal visit is associated with miscarriage.

DESIGN

This was a prospective cohort study.

SETTING

The study was conducted at a tertiary obstetric center.

PARTICIPANTS

A total of 993 asymptomatic pregnant women with a gestation of 6 weeks or longer attending routine antenatal booking visit were recruited between January 2010 and December 2012.

MAIN OUTCOME MEASURES

Plasma kisspeptin and serum hCG were measured during the antenatal booking visit. Pregnancy outcome was recorded prospectively.

RESULTS

Plasma kisspeptin correlated with gestation (r(2) = 0.57; P < .0001). Gestational age-corrected (multiples of median) plasma kisspeptin was 60.4% lower (P < .001), and multiples of median-hCG was 36.1% lower (P < .001) in women later diagnosed with miscarriage compared with women without miscarriage. Increased plasma kisspeptin was associated with reduced miscarriage risk, even after adjusting for age, body mass index, gestational age, smoking, and blood pressure [odds ratio 0.13 (95% confidence interval 0.08-0.22), P = .0001]. Kisspeptin had a higher diagnostic performance for miscarriage than hCG (receiver-operator characteristic-area under the curve 0.899 ± 0.025 plasma kisspeptin; 0.775 ± 0.040, serum hCG, P < .01 vs plasma kisspeptin).

CONCLUSION

Our data suggest for the first time that a single plasma kisspeptin measurement taken during the antenatal booking visit provides a potential novel marker for identifying asymptomatic pregnant women at a gestation of 6 weeks or greater at increased risk of miscarriage.

Risk of placental dysfunction disorders after prior miscarriages: a population-based study

OBJECTIVE

The objective of the investigation was to study the association between prior miscarriages and the risks of placental dysfunction disorders, including preeclampsia, stillbirth, birth of a small for gestational age (SGA) infant, placental abruption, and spontaneous preterm birth.

STUDY DESIGN

In a population-based cohort study including 619,587 primiparous women, we estimated risks of placental dysfunction disorders for women with 1 (n = 68,185), 2 (n = 11,410) and 3 or more (n = 3823) self-reported prior miscarriages. Risks were calculated as odds ratios by unconditional logistic regression analysis and adjustments were made for maternal age, early pregnancy body mass index, height, smoking habits, country of birth, years of formal education, in vitro fertilization, chronic hypertension, pregestational diabetes, hypothyroidism, systemic lupus erythematosis, fetal sex, and year of childbirth.

RESULTS

Compared with women with no prior miscarriage, women with 1 prior miscarriage had almost no increased risks. Women with 2 prior miscarriages had increased risks of spontaneous preterm birth, preterm (<37 weeks) SGA infant, and placental abruption. The rates of all disorders were higher for women with 3 or more prior miscarriages compared with women without prior miscarriages: preeclampsia, 5.83% vs 4.27%; stillbirth, 0.69% vs 0.33%, SGA infant, 5.09% vs 3.22%, placental abruption, 0.81% vs 0.41%; and spontaneous preterm birth, 6.45% vs 4.40%. The adjusted odds ratios for preterm (<37 weeks) disorders in women with 3 prior miscarriages were approximately 2.

CONCLUSION

History of 2 or more miscarriages is associated with an increased risk of placental dysfunction disorders and should be regarded as a risk factor in antenatal care.

Pregnancy outcome in women with threatened miscarriage: a year study

Introduction:

Patients with threatened miscarriage associated with adverse pregnancy outcomes because of associated pregnancy and labor complications.

Objectives:

To evaluate the effect of threatened miscarriage on early and late pregnancy outcome.

Methods:

A retrospective case–controlled study was performed on 89 women with threatened miscarriage (study group) at Maternity and Children Hospital Buraidah, KSA from January 2010 to December 2010. They were matched for age and parity to 45 cases (control group) attending route antenatal clinic at the same time. Data recorded included, demographic characteristics and detailed pregnancy outcome and ultrasound finding including gestational age, cardiac activity and subchorionic hematoma.

Results:

The overall adverse pregnancy outcome was significantly higher in the studied cases compared to the control group (p=015).The miscarriage rate was significantly higher in study group compared to the controls group, (16.9%vs 2.2%, p=0000). Preterm delivery, babies with low birth weight and premature rupture of membranes were significantly higher in the miscarriage group compared to the controls group, (15.7% vs 2.2%, p=0.001), (15.7% vs 2.2%), p=0.001) and (6.7%) vs 4.45), p=0.016). There were no significant differences in other pregnancy outcomes.

Conclusion:

threatened miscarriage is associated with increased incidence of adverse pregnancy outcome. The risk is specially increased in premature rupture of the membranes, preterm delivery and neonatal birth weight.

Maternal risk factors and neonatal outcome of the admitted patients for preterm spontaneous uterine contractions

BACKGROUND

Preterm birth (PTB) is one of the most important unsolved problems in reproductive medicine. This study aims to evaluate several maternal risk factors and outcome of pregnancies who were admitted for preterm spontaneous uterine contractions (PSUC).

METHODS

From September 2007 to February 2009, 327 cases who were admitted for PSUC were retrospectively studied. They were classified according to their fetal numbers and presence of true versus threatened preterm labor (PTL).

RESULTS

There were 297 (90.82%) singleton, 27 (8.25%) twin and 3 (0.91%) triplet pregnancies. Only 12 women (3.6%) fulfilled the ACOG criteria for PTL who delivered in a few hours and 315 cases (96.3%) were classified as threatened PTL and most of them were discharged undelivered from the hospital. 103 cases were missed and 224 mothers and their 247 neonates remained. 121 women from this cohort had PTB and delivered before 259 days (54%). Pregnancy outcomes including; the time interval between admission for PSUC and delivery, the mean gestational ages at birth, birth weights, number and duration of NICU admissions were evaluated in each group.

CONCLUSION

Regular uterine contractions even in the absence of cervical changes should be considered as a potential risk factor for PTB. The most frequently associated maternal risk factors were history of abortion, infertility and previous PTB, and the most frequently associated complications were preterm rupture of membranes, vaginal bleeding and febrile diseases.

Antenatal depressive symptoms and preterm birth: a prospective study of a Swedish national sample

BACKGROUND

Preterm birth is the principal risk factor for neonatal morbidity and mortality. The objective of this study was to investigate the association between antenatal depressive symptoms and preterm birth.

METHODS

The study included a national sample of 2,904 pregnant women who were recruited at their first booked visit to antenatal clinics in Sweden. Data on depressive symptoms, and sociodemographic and reproductive background were collected by questionnaires. Depressive symptoms were assessed by the Edinburgh Postnatal Depression Scale (EPDS). The average length of gestation at the time for completion of the questionnaire was 16 weeks. Data on gestational length were extracted from the Swedish Medical Birth Register. Multiple logistic regression analyses were conducted to estimate the risk of preterm birth associated with antenatal depressive symptoms.

RESULTS

The presence of antenatal depressive symptoms above a cutoff score of 12 or higher on the EPDS increased the risk for preterm birth (OR: 1.56; 95% CI: 1.03-2.35). Being of age 35 years and over, being a primipara, and having experienced a previous miscarriage were also shown to be significant predictors in a multivariate model.

CONCLUSION

Pregnant women reporting antenatal depressive symptoms are at elevated risk of preterm birth.

Obstetric outcome after early placental complications

PURPOSE OF REVIEW

To evaluate the impact of early pregnancy complications involving placentation and early placental development on adverse obstetric outcome in ongoing and subsequent pregnancies.

RECENT FINDINGS

We found an increased risk of adverse outcome (odds ratio >2.0) in ongoing pregnancies of preterm delivery (PTD), very preterm delivery (VPTD), placental abruption, small for gestational age (SGA), low birth weight (LBW) and very LBW (VLBW) after a threatened miscarriage episode; pregnancy-induced hypertension, preeclampsia, placental abruption, PTD, SGA and low 5-min Apgar score following the detection of an intrauterine haematoma; and VPTD, VLBW and perinatal death after a vanishing twin phenomenon. In subsequent pregnancies, the risk of perinatal death was increased (odds ratio >2.0) after a single miscarriage, the risk of VPTD after two or more miscarriages, the risk of placenta previa, premature preterm rupture of membranes, PTD, VPTD and LBW after recurrent miscarriage and the risk of VPTD after two or more terminations of pregnancy.

SUMMARY

Our analysis of the literature review indicates a link between early pregnancy complications involving the placenta and subsequent adverse obstetric and perinatal outcomes. Some of these associations are based on limited or small uncontrolled studies. Larger population-based prospective controlled studies have recently been published confirming most of these findings. This suggests that the early detection of these risk factors could improve the screening of women at high risk of specific obstetric complications in ongoing and subsequent pregnancies.

Modelling prior reproductive history to improve prediction of risk for very preterm birth

In published studies of preterm birth, analyses have usually been centred on individual reproductive events and do not account for the joint distributions of these events. In particular, spontaneous and induced abortions have often been studied separately and have been variously reported as having no increased risk, increased risk or different risks for subsequent preterm birth. In order to address this inconsistency, we categorised women into mutually exclusive groups according to their reproductive history, and explored the range of risks associated with different reproductive histories and assessed similarities of risks between different pregnancy histories. The data were from a population-based case-control study, conducted in Victoria, Australia. The study recruited women giving birth between April 2002 and April 2004 from 73 maternity hospitals. Detailed reproductive histories were collected by interview a few weeks after the birth. The cases were 603 women who had had a singleton birth between 20 and less than 32 weeks gestation (very preterm births including terminations of pregnancy) and the controls were 796 randomly selected women from the population who had had a singleton birth of at least 37 completed weeks gestation. All birth outcomes were included. Unconditional logistic regression was used to assess the association of very preterm birth with type and number of prior abortions, prior preterm births and sociodemographic factors. Using the complex combinations of prior pregnancy experiences of women (including nulligravidity), we showed that a history of prior childbirth (at term) with no preterm births gave the lowest risk of very preterm birth. With this group as the reference category, odds ratios of more than two were associated with all other prior reproductive histories. There was no evidence of difference in risk between types of abortion (i.e. spontaneous or induced) although the risk increased if a prior preterm birth had also occurred. There was an increasing risk of very preterm birth associated with increasing numbers of abortions. This method of data analysis reveals consistent and similar risks for very preterm birth following spontaneous or induced abortions. The findings point to the need to explore commonalities rather than differences in regard to the impact of abortion on subsequent births.

Modelling sequence of prior pregnancies on subsequent risk of very preterm birth

The prevalence and intractability of preterm birth is known as is its association with reproductive history, but the relationship with sequence of pregnancies is not well studied. The data were from a population-based case-control study, conducted in Victoria, Australia. The study recruited women giving birth between April 2002 and April 2004 from 73 maternity hospitals. Detailed reproductive histories were collected by interview a few weeks after the birth. The cases were 603 women having a singleton birth between 20 and <32 weeks gestation (very preterm births including terminations of pregnancy). The controls were 796 randomly selected women from the population having a singleton birth of at least 37 completed weeks gestation. Unconditional logistic regression was used to assess the association of very preterm birth with sequence of pregnancies defined by their outcome (prior abortion - spontaneous or induced, and prior preterm or term birth) with adjustment for sociodemographic factors. The outcomes of each prior pregnancy, stratified by pregnancy order, and starting with the pregnancy immediately before the index or control pregnancy, were categorised as one of abortion, preterm birth or term birth. We showed that each of these prior pregnancy events was an independent risk of very preterm birth. This finding does not support the hypothesis of a neutralising effect of a term birth after an abortion on the subsequent risk for very preterm birth and is further evidence for the cumulative or increasing risk associated with increasing numbers of prior abortions or preterm births.

Matching risk and resources in high-risk pregnancies

OBJECTIVE

To evaluate the joint impact of pregnancy risk and the timing of referral of high-risk pregnancies from obstetricians to maternal fetal medicine (MFM) sub-specialists on gestational age (GA) at delivery.

METHODS

For the period 1992-2002, 2567 consecutive deliveries from pregnancies of at least 23 weeks gestational age (GA) from a community-level sub-specialty perinatal center were studied. A multiple regression model was developed specifying the impact of various risk factors and referral timing.

RESULTS

Prior pregnancy risk was inversely related to GA at birth. Referral timing, operationalized as a continuous variable, did not have a significant additive impact on GA at birth, but several dummy-variable interaction effects combining risk factors and referral before 20 weeks as a dichotomy were significant.

CONCLUSION

There are identifiable risks that occur either before the pregnancy or early into it that should lead to early referral to a sub-specialist because of their impact on GA at birth. Early referral is an important tactic in a larger preterm prevention strategy, but it needs to be embedded in a broader maternal-fetal health initiative in which both generalists and sub-specialists play important roles.

Infection with Parvovirus B19 and Herpes viruses in early pregnancy and risk of second trimester miscarriage or very preterm birth

We investigated whether infections with Parvovirus B19 and Herpes viruses in early pregnancy increase risks of second trimester miscarriage or delivery before 32 gestational weeks. Blood samples taken in early pregnancy were analyzed for Parvovirus B19 or Herpes viruses. Viremia was found in blood samples of 11 (4.7%) women with second trimester miscarriage and 10 (3.7%) women with very preterm birth, compared to 5 (1.7%) women who delivered at term, corresponding to adjusted odds ratios [95% CI] of 3.32 [0.93, 11.8] and 2.21 [0.71, 6.84], respectively. In stratified analyses, Parvovirus B19 viremia was associated with adjusted odds ratios of 3.76 [0.77, 18.3] for second trimester miscarriage and 2.66 [0.64, 11.1] for very preterm birth. Corresponding odds ratios for Human Herpes virus 6 viremia was 2.52 [0.33, 19.5] and 1.08 [0.14, 8.08], respectively. In conclusion, this study lends some support to the hypothesis that women with viremia in early pregnancy may face an increased risk of second trimester miscarriage or very preterm birth. Studies with larger sample sizes are needed.

Maternal obesity and neonatal mortality according to subtypes of preterm birth

OBJECTIVE

To examine the association between prepregnancy body mass index (BMI) and neonatal mortality while accounting for the timing of delivery and subtypes of preterm birth.

METHODS

The study population included 85,375 liveborn singletons of mothers in the Danish National Birth Cohort (1996-2002) who were interviewed during the second trimester. Information about pregnancy outcomes and neonatal deaths (n=230) was obtained from national registers. The association was estimated by Cox regression analyses and results were presented as hazard ratios with 95% confidence intervals (CIs).

RESULTS

Compared with infants of mothers who were at a normal weight before pregnancy (BMI of 18.5 or more but less than 25), neonatal mortality was increased in infants of mothers who were overweight (BMI of 25 or more but less than 30) or obese (BMI of 30 or more) (adjusted hazard ratios 1.7, CI 1.2-2.5, and 1.6, CI 1.0-2.4, respectively). For preterm infants (n=3,934, 136 deaths), neonatal mortality in infants born after preterm premature rupture of membranes (PROM) was significantly increased if they were born to an overweight or obese mother (adjusted hazard ratios 3.5, CI 1.4-8.7, and 5.7, CI 2.2-14.8). There were no associations between high BMI and neonatal mortality in infants born after spontaneous preterm birth without preterm PROM or in infants born after induced preterm delivery.

CONCLUSION

High maternal weight seems to increase the risk of neonatal mortality, especially in infants born after preterm PROM. Inflammation or infection related to obesity may be part of the causal pathway.

LEVEL OF EVIDENCE

II.

Epidemiology and environmental factors in preterm labour

An epidemiological and environmental approach is the appropriate starting point to understanding preterm labour. Although there are multiple aetiologies it seems likely that anthropometric and environmental risk factors in combination with inherent genetic susceptibilities contribute to an increased risk of preterm labour for certain women. Poct 2pulation-based studies identifying risk factors and quantifying outcomes facilitate informed counselling and provide a framework for developing prediction tools. Carefully conducted case-control and cohort studies identify associations that may contribute to an understanding of causation. A combined approach encompassing epidemiology, pathophysiology and clinical research is required to understand the aetiologies, prevention and optimal management of preterm labour. This review focuses on the epidemiology of preterm labour and the role of environmental factors.

Maternal and biochemical predictors of spontaneous preterm birth among nulliparous women: a systematic analysis in relation to the degree of prematurity

BACKGROUND

Nulliparous women are at increased risk of spontaneous preterm birth. Other maternal and biochemical risk factors have also been described. However, it is unclear whether these associations are strong enough to offer clinically useful prediction. It is also unclear whether the predictive power of these factors varies in relation to the degree of prematurity.

METHODS

The risk of spontaneous preterm birth associated with maternal characteristics and second trimester serum screening data was analysed in a dataset of 84 391 first births in Scotland between 1992 and 2001 using Cox and logistic regression. Variation in the relative risk of preterm birth over the period 24-36 weeks was assessed using a test of the proportional hazards assumption.

RESULTS

The risk of spontaneous preterm birth was positively associated with maternal serum levels of alpha-fetoprotein, socioeconomic deprivation, number of previous therapeutic abortions, smoking, and being unmarried and was negatively associated with height and body mass index. The risk of preterm birth at 24-28 weeks, but not later gestations, was increased in association with maternal levels of human chorionic gonadotrophin >95th percentile, maternal age <20, and two or more previous miscarriages. The area under the receiver operating characterise curve (95% CI) for models based on these factors was 0.67 (0.63-0.71) for 24-28 weeks, 0.65 (0.62-0.68) for 29-32 weeks, and 0.62 (0.61-0.63) for 33-36 weeks.

CONCLUSIONS

Time to event analytic methods can identify factors that are differentially associated with spontaneous preterm birth according to the degree of prematurity. However, models based on maternal and biochemical data perform poorly as a screening test for any degree of spontaneous preterm birth.