Stillbirth as a risk factor for subsequent infant mortality

Association of previous stillbirth with subsequent perinatal outcomes: a systematic review and meta-analysis of cohort studies

OBJECTIVE

We conducted a systematic review and meta-analysis to examine the relationship between stillbirth and various perinatal outcomes in subsequent pregnancy.

DATA SOURCES

PubMed, the Cochrane Library, Embase, Web of Science, and CNKI databases were searched up to July 2023.

STUDY ELIGIBILITY CRITERIA

Cohort studies that reported the association between stillbirth and perinatal outcomes in subsequent pregnancies were included.

METHODS

We conducted this systematic review and meta-analysis in accordance with the PRISMA guidelines. Statistical analysis was performed using R and Stata software. We used random-effects models to pool each outcome of interest. We performed a meta-regression analysis to explore the potential heterogeneity. The certainty (quality) of evidence assessment was performed using the GRADE approach.

RESULTS

Nineteen cohort studies were included, involving 4,855,153 participants. From these studies, we identified 28,322 individuals with previous stillbirths who met the eligibility criteria. After adjusting for confounders, evidence of low to moderate certainty indicated that compared with women with previous live births, women with previous stillbirths had higher risks of recurrent stillbirth (odds ratio, 2.68; 95% confidence interval, 2.01-3.56), preterm birth (odds ratio, 3.15; 95% confidence interval, 2.07-4.80), neonatal death (odds ratio, 4.24; 95% confidence interval, 2.65-6.79), small for gestational age/intrauterine growth restriction (odds ratio, 1.3; 95% confidence interval, 1.0-1.8), low birthweight (odds ratio, 3.32; 95% confidence interval, 1.46-7.52), placental abruption (odds ratio, 3.01; 95% confidence interval, 1.01-8.98), instrumental delivery (odds ratio, 2.29; 95% confidence interval, 1.68-3.11), labor induction (odds ratio, 4.09; 95% confidence interval, 1.88-8.88), cesarean delivery (odds ratio, 2.38; 95% confidence interval, 1.20-4.73), elective cesarean delivery (odds ratio, 2.42; 95% confidence interval, 1.82-3.23), and emergency cesarean delivery (odds ratio, 2.35; 95% confidence interval, 1.81-3.06) in subsequent pregnancies, but had a lower rate of spontaneous labor (odds ratio, 0.22; 95% confidence interval, 0.13-0.36). However, there was no association between previous stillbirth and preeclampsia (odds ratio, 1.72; 95% confidence interval, 0.63-4.70) in subsequent pregnancies.

CONCLUSION

Our systematic review and meta-analysis provide a more comprehensive understanding of adverse pregnancy outcomes associated with previous stillbirth. These findings could be used to inform counseling for couples who are considering pregnancy after a previous stillbirth.

Stillbirth and neonatal mortality in a subsequent pregnancy following stillbirth: a population-based cohort study

BACKGROUND

A history of stillbirth is a risk factor for recurrent fetal death in a subsequent pregnancy. Reported risks of recurrent fetal death are often not stratified by gestational age. In subsequent pregnancies increased rates of medical interventions are reported without evidence of perinatal benefit. The aim of this study was to estimate gestational-age specific risks of recurrent stillbirth and to evaluate the effect of obstetrical management on perinatal outcome after previous stillbirth.

METHODS

A retrospective cohort study in the Netherlands was designed that included 252.827 women with two consecutive singleton pregnancies (1^st and 2^nd delivery) between 1999 and 2007. Data was obtained from the national Perinatal Registry and analyzed for pregnancy outcomes. Fetal deaths associated with a congenital anomaly were excluded. The primary outcome was the occurrence of stillbirth in the second pregnancy stratified by gestational age. Secondary outcome was the influence of obstetrical management on perinatal outcome in a subsequent pregnancy.

RESULTS

Of 252.827 first pregnancies, 2.058 pregnancies ended in a stillbirth (8.1 per 1000). After adjusting for confounding factors, women with a prior stillbirth have a two-fold higher risk of recurrence (aOR 1.96, 95% CI 1.07-3.60) compared to women with a live birth in their first pregnancy. The highest risk of recurrence occurred in the group of women with a stillbirth in early gestation between 22 and 28 weeks of gestation (a OR 2.25, 95% CI 0.62-8.15), while after 32 weeks the risk decreased. The risk of neonatal death after 34 weeks of gestation is higher in women with a history of stillbirth (aOR 6.48, 95% CI 2.61-16.1) and the risk of neonatal death increases with expectant obstetric management (aOR 10.0, 95% CI 2.43-41.1).

CONCLUSIONS

A history of stillbirth remains an important risk for recurrent stillbirth especially in early gestation (22-28 weeks). Women with a previous stillbirth should be counselled for elective induction in the subsequent pregnancy at 37-38 weeks of gestation to decrease the risk of perinatal death.

Estimation of pregnancy losses attributable to exposure to ambient fine particles in south Asia: an epidemiological case-control study

BACKGROUND

Maternal exposure to ambient particulate matter (PM_2·5) is associated with pregnancy loss (ie, stillbirth and miscarriage). South Asia has the highest burden of pregnancy loss globally and is one of the most PM_2·5 polluted regions in the world. However, knowledge of the relevant exposure-response function for mothers is insufficient.

METHODS

In this epidemiological case-control study, we collected data from Demographic and Health Surveys from India, Pakistan, and Bangladesh for the period 1998-2016 for women who reported at least one pregnancy loss and one or more livebirths. We assessed ambient exposure during gestation with satellite-based PM_2·5 measurements for the period. To derive the exposure-response function, we did a self-compared case-control study in which each case of pregnancy loss was compared with a successful livebirth control or controls by the same mother. Using the estimated exposure-response function, we quantified pregnancy losses attributable to PM_2·5 in the region for the period 2000-16 using a standard risk assessment approach.

FINDINGS

We assessed data for 34 197 mothers, who had at least one pregnancy loss and one or more livebirth, of whom 26 282 (76·9%) were from India, 4228 (12·4%) were from Pakistan, and 3687 (10·8%) were from Bangladesh. The 34 197 cases of pregnancy loss were matched with 76 282 livebirth controls. The mean level of PM_2·5 exposure was 56·00 μg/m³ (SD 30·82) for cases and 54·57 μg/m³ (31·73) for controls. After adjustment for maternal age, non-linear terms for temperature and humidity, seasonal variation, and long-term trends, each 10 μg/m³ increment in PM_2·5 was associated with an odds ratio for pregnancy loss of 1·03 (95% CI 1·02-1·05). According to the estimated non-linear exposure-response function by age and urban residence versus rural residence, for the period 2000-16, an estimated 349 681 (95% CI 152 932-489 493) pregnancy losses per year were attributed to ambient air exposure of more than 40 μg/m³ (the annual PM_2·5 standard of India), accounting for 7·1% (95% CI 3·3-31·2) of the total annual pregnancy loss burden in south Asia for this period. However, our estimates could be biased because of the limitations of the data (eg, misclassification of induced and spontaneous pregnancy losses).

INTERPRETATION

Our findings add to epidemiological evidence of the association between pregnancy loss and PM_2·5. Suboptimal air quality contributes to a considerable fraction of total pregnancy loss in south Asia. Controlling PM_2·5 pollution will promote maternal health in south Asia.

FUNDING

Chinese Natural Science Foundation and Ministry of Science and Technology of China.

Comprehensive Assessment of Risk Factors of Cause-Specific Infant Deaths in Japan

Background

Public attention is given to infants with socially high risks of child abuse and neglect, while clinical attention is provided to infants with a biologically high risk of diseases. However, few studies have systematically evaluated how biological or social factors cross over and affect cause-specific infant mortality.

Methods

We linked birth data with death data from the Japanese national vital statistics database for all infants born from 2003–2010. Using multivariate logistic regression, we examined the association between biological and social factors and infant mortality due to medical causes (internal causes), abuse (intentional external causes), and accidents (unintentional external causes).

Results

Of 8,941,501 births, 23,400 (0.26%) infants died by 1 year of age, with 21,884 (93.5%) due to internal causes, 175 (0.75%) due to intentional external causes, and 1,194 (5.1%) due to unintentional external causes. Infants with high social risk (teenage mothers, non-Japanese mothers, single mothers, unemployed household, four or more children in the household, or birth outside of health care facility) had higher risk of death by intentional, unintentional, and internal causes. Infant born with small for gestational age and preterm had higher risks of deaths by internal and unintentional causes, but not by intentional causes.

Conclusions

Both biological as well as social factors were associated with infant deaths due to internal and external causes. Interdisciplinary support from both public health and clinical-care professionals is needed for infants with high social or biological risk to prevent disease and injury.

Adverse Perinatal Outcome in Subsequent Pregnancy after Stillbirth by Placental Vascular Disorders

Objective

To evaluate outcome in the pregnancy following a stillbirth (SB) by a placental vascular disorders.

Study Design

A prospective, observational, multicenter study was conducted in woman with a history of stillbirth (> 22 weeks) between 2005 and June 2013, in 3 Italian University Hospitals. Causes of SB were previously identified after extensive investigations. Pregnant women were enrolled within the first trimester. The main outcome was “adverse neonatal outcome”, including perinatal death, fetal growth restriction, early preterm birth <33+6 weeks, hypoxic-ischemic encephalopathy, intracranial hemorrhage or respiratory distress.

Results

Out of 364 index pregnancies, 320 women (87.9%) had a subsequent pregnancy during the study period. Forty-seven had an early pregnancy loss. Out of 273 babies, 67 (24.5%) had an adverse perinatal outcome, including 1 SB and 1 early neonatal death (3.7/1000).

Women who had a SB related to placental vascular disorders (39.6%), were at higher risk of an adverse neonatal outcome compared with women whose SB was unexplained or resulted from other causes (Adj. OR = 2.1, 95%CI: 1.2–3.8). Moreover, also obesity independently predicts an adverse perinatal outcome (Adj OR = 2.1, 95%CI: 1.1–4.3).

Conclusion

When previous SB is related to placental vascular disorders there is a high risk for adverse neonatal outcomes in the subsequent pregnancy. Maternal obesity is an additional risk factor.

Elective Delivery at Term after a Previous Unexplained Intra-Uterine Fetal Death: Audit of Delivery Outcome at Tygerberg Hospital, South Africa

Objectives

To assess the delivery outcome in a pregnancy with a previous unexplained intra-uterine death by elective induction of labour at term.

Methods

An audit of the pregnancy outcome of all women within the catchment area with a current singleton pregnancy; and a previous unexplained or unexplored singleton fetal demise ≥24 weeks (or 500 grams birth weight if gestation unknown) after planned routine induction of labour at full term (39-40 weeks).

Results

During the audit period, 306 patients with a previous intra-uterine fetal death were referred for further management. Of these, 161 had a clear indication for earlier intervention and were excluded from the protocol. Of the remaining 145 patients, 9 met further exclusion criteria and there were 2 patients who defaulted. Forty-two of the remaining study patients (with no known previous medical problems) developed complications during their antenatal course that necessitated a change in clinical management and earlier (<39 weeks) delivery. Of the remaining 92 patients in the audit, 47 (51%) went into spontaneous labour before their induction date; all 92 women delivered without major complications. There were no intra-uterine deaths prior to induction.

Conclusions

Careful follow up at a high risk clinic identifies new or concealed maternal or fetal complications in 29% of patients with a previous intra-uterine death and no obvious maternal or fetal disease in the index pregnancy. When all risks are excluded and the pregnancy allowed to progress to full term (39-40 weeks) before an induction is offered, 50% will go into spontaneous labour.

Recurrence of perinatal death in Northern Tanzania: a registry based cohort study

Background

Perinatal mortality is known to be high in Sub-Saharan Africa. Some women may carry a particularly high risk which would be reflected in a high recurrence risk. We aim to estimate the recurrence risk of perinatal death using data from a hospital in Northern Tanzania.

Methods

We constructed a cohort study using data from the hospital based KCMC Medical Birth Registry. Women who delivered a singleton for the first time at the hospital between 2000 and 2008 were followed in the registry for subsequent deliveries up to 2010 and 3,909 women were identified with at least one more delivery within the follow-up period. Recurrence risk of perinatal death was estimated in multivariate models analysis while adjusting for confounders and accounting for correlation between births from the same mother.

Results

The recurrence risk of perinatal death for women who had lost a previous baby was 9.1%. This amounted to a relative risk of 3.2 (95% CI: 2.2 - 4.7) compared to the much lower risk of 2.8% for women who had had a surviving baby. Recurrence contributed 21.2% (31/146) of perinatal deaths in subsequent pregnancies. Preeclampsia, placental abruption, placenta previa, induced labor, preterm delivery and low birth weight in a previous delivery with a surviving baby were also associated with increased perinatal mortality in the next pregnancy.

Conclusions

Some women in Tanzanian who suffer a perinatal loss in one pregnancy are at a particularly high risk of also losing the baby of a subsequent pregnancy. Strategies of perinatal death prevention that target pregnant women who are particularly vulnerable or already have experienced a perinatal loss should be considered in future research.

Small size for gestational age and the risk for infant mortality in the subsequent pregnancy

PURPOSE

To examine the association between small for gestational age (SGA) in the first pregnancy and risk for infant mortality in the second pregnancy.

METHODS

This is a population-based, retrospective cohort study in which we used the Missouri maternally linked cohort dataset for 1978-2005. Analyses were restricted to women who had two singleton pregnancies during the study period. The exposure was SGA in the first pregnancy, whereas the primary outcome was infant mortality in the second pregnancy. Kaplan-Meier Estimate and Cox proportional hazard regression were conducted.

RESULTS

Infant mortality was significantly greater among mothers with previous SGA (P < .01). A persistent association of previous SGA with subsequent infant mortality was observed (adjusted hazard ratio [AHR] 1.35, 95% confidence interval [95% CI] 1.24-1.48). Race-specific data illustrated that black women with a previous SGA birth were 40% more likely to experience infant mortality (AHR 1.40, 95% CI 1.21-1.63) than their counterparts without a history of SGA, but white women with a previous SGA had an increased risk of 31% (AHR 1.31, 95% CI 1.17-1.46).

CONCLUSIONS

Women with previous SGA bear increased risks for subsequent infant mortality, which was greater among black mothers. Hence, SGA plays an important role in the black-white disparity in infant mortality. Women's previous childbearing experiences could serve as important criterion in determining appropriate interconception strategies to improve infant health and survival.