Invited Commentary: Preventable Pregnancy Loss Is a Public Health Problem

Job loss during pregnancy and the risk of miscarriage and stillbirth

STUDY QUESTION

Does the exposure to job loss during pregnancy increase the risk of miscarriage or stillbirth?

SUMMARY ANSWER

The experience of own or partner's job loss during the pregnancy is associated with an increased risk of miscarriageand stillbirth.

WHAT IS KNOWN ALREADY

Prior research on the psycho-social aspect of pregnancy loss has investigated the contextual and the individual-level stressors. At the contextual level, natural disasters, air pollution, and economic downturns are associated with higher risk of pregnancy loss. At the individual level, intense working schedules and financial strain are linked with increased risk of pregnancy loss both at early and later stages of the gestation.

STUDY DESIGN, SIZE, DURATION

This work draws on high-quality individual data of 'Understanding Society', a longitudinal survey that has interviewed a representative sample of households living in the UK annually since 2009. Approximately 40 000 households were recruited. The analyses use all the available survey waves (1-12, 2009-2022).

PARTICIPANTS/MATERIALS, SETTING, METHODS

The final sample consisted of 8142 pregnancy episodes that contain complete informationon pregnancy outcome and date of conception. Ongoing pregnancies at the time of the interview were excluded from the final sample. The outcome variable indicated whether a pregnancy resulted in a live birth or a pregnancy loss whereas the exposure variable identified the women's or their partner's job loss because of redundancy or a dismissal. Logistic regression models were employed to estimate the relation between job loss during pregnancy and pregnancy loss. The models were adjusted for an array of socio-demographic and economic characteristics following a stepwise approach. Several sensitivity analyses complemented the main findings.

MAIN RESULTS AND THE ROLE OF CHANCE

Baseline models controlling for women's demographic background and prior experience of miscarriage estimated an increased risk of pregnancy loss when women were exposed to their own or their partner's job loss during their pregnancy (odds ratio (OR) = 1.99, 95% CI: 1.32, 2.99). When the models were adjusted for all socio-economic and partnership-related covariates the association remained robust (OR = 1.81, 95% CI: 1.20, 2.73).

LIMITATIONS, REASONS FOR CAUTION

First, the pregnancy outcome and the date of conception were self-reported and may besubjected to recall and social desirability bias. Second, although we adjusted for an array socio-demographic characteristics and self-reported health, other contextual factors might be correlated with both job loss and pregnancy loss. Third, owing to the limited sample size, we could not assess if the main finding holds across different socio-economic strata.

WIDER IMPLICATIONS OF THE FINDINGS

By showing that exposure to a job loss during pregnancy increases the risk of miscarriage and stillbirth, we underline the relevance of pregnancy loss as a preventable public health matter. This result also calls for policy designthat enhances labour market protection and social security buffers for pregnant women and their partners.

STUDY FUNDING/COMPETING INTERESTS

The authors received the following financial support for the research, authorship, and/or publication of this article: H2020 Excellent Science, H2020 European Research Council, Grant/Award Number: 694262 (project DisCont-Discontinuities in Household and Family Formation) and the Economic and Social Research Centre on Micro-Social Change (MiSoC). There are no conflicts of interest to declare.

Does a short luteal phase correlate with an increased risk of miscarriage? A cohort study

BACKGROUND

Miscarriage is defined as spontaneous loss of pregnancy prior to 20 weeks gestation. With an estimated risk of 15% of clinically confirmed pregnancies ending in miscarriage, it is the most common adverse event in pregnancy. Woman's age is the primary risk factor for miscarriage, while medical conditions, including hormonal abnormalities, are also associated. Progesterone is essential for maintaining pregnancy. A short luteal phase may reflect inadequate levels of progesterone production, but it is unclear whether a short luteal phase correlates with an increase in the risk of miscarriage.

METHODS

Using a cohort study design, we conducted a secondary data analysis from four cohorts of couples who used a standardized protocol to track biomarkers of the female cycles. A short luteal phase was defined as less than 10 days, with < 11, < 9, and < 8 days as alternate definitions in sensitivity analyses. We included women who experienced a pregnancy with a known outcome, identified the length of the luteal phase in up to 3 cycles prior to conception and assessed the relationship with miscarriage using a modified Poisson regression analysis, adjusting for demographic characteristics, smoking, alcohol use and previous pregnancy history.

RESULTS

In our sample of 252 women; the overall miscarriage rate was 18.7%. The adjusted incident risk ratio of miscarriage in women who had at least one short luteal phase < 10 days, compared to those who had none, was 1.01 (95% CI: 0.57, 1.80) Similar null risk was found when assessing alternative lengths of short luteal phase. Women who had short luteal phases < 10 days in all 3 cycles prior to the conception cycle had an incident risk ratio of 2.14 (95% CI: 0.7, 6.55).

CONCLUSIONS

Our study found that a short luteal phase in the three cycles prior to conception was not associated with higher rates of miscarriage in an international cohort of women tracking their cycles, but our sample size was limited. Further research to determine if short luteal phases or luteal phase deficiency is associated with early pregnancy losses among preconception cohorts with daily tracking of cycle parameters, in addition to progesterone and human chorionic gonadotropin levels, is warranted. Additionally, future studies should include women with recurrent short luteal phases as a more likely risk factor than isolated short luteal phases.

Environmental hazards, social inequality, and fetal loss: Implications of live-birth bias for estimation of disparities in birth outcomes

Restricting to live births can induce bias in studies of pregnancy and developmental outcomes, but whether this live-birth bias results in underestimating disparities is unknown. Bias may arise from collider stratification due to an unmeasured common cause of fetal loss and the outcome of interest, or depletion of susceptibles, where exposure differentially causes fetal loss among those with underlying susceptibility.

METHODS

We conducted a simulation study to examine the magnitude of live-birth bias in a population parameterized to resemble one year of conceptions in California (N = 625,000). We simulated exposure to a non-time-varying environmental hazard, risk of spontaneous abortion, and time to live birth using 1000 Monte Carlo simulations. Our outcome of interest was preterm birth. We included a social vulnerability factor to represent social disadvantage, and estimated overall risk differences for exposure and preterm birth using linear probability models and stratified by the social vulnerability factor. We calculated how often confidence intervals included the true point estimate (CI coverage probabilities) to illustrate whether effect estimates differed qualitatively from the truth.

RESULTS

Depletion of susceptibles resulted in a larger magnitude of bias compared with collider stratification, with larger bias among the socially vulnerable group. Coverage probabilities were not adversely affected by bias due to collider stratification. Depletion of susceptibles reduced coverage, especially among the socially vulnerable (coverage among socially vulnerable = 46%, coverage among nonsocially vulnerable = 91% in the most extreme scenario).

CONCLUSIONS

In simulations, hazardous environmental exposures induced live-birth bias and the bias was larger for socially vulnerable women.

Weathering the storm; a review of pre-pregnancy stress and risk of spontaneous abortion

The Weathering Effect is a theory that links stress exposure, over the life-course, with racial disparities in reproductive outcomes, through the effects of social adversity on a woman's body. The concept of maternal "weathering" captures cumulative somatic and psychological adversities that can exacerbate the effects of aging. Much of the evidence for weathering comes from observational studies linking self-report measures with reproductive outcomes. The purpose of this review is to explore biological mechanisms that underlie these observations. We focus on spontaneous abortion because this event is understudied despite evidence of racial disparities in this outcome. Spontaneous abortion is the most common pregnancy failure, and it happens early in pregnancy. Early pregnancy is a time most susceptible to the harmful effects of immune dysregulation that may, in part, result from adversities experienced before pregnancy begins. In exploring these mechanisms, we draw on well-defined signaling processes observed in the stressor-depression relationship. Pro-inflammatory dysregulation, for example, has particular relevance to immunological control occurring early in pregnancy. Early pregnancy immunologic changes affect the trajectories of pregnancy via control of trophoblastic invasion. Within the first few weeks of pregnancy, uterine derived cytokines operate within cytokine networks and play a critical role in this invasion. Programming for pro-inflammatory dysregulation can occur before conception. This dysregulation, brought into early pregnancy, has implications for viability and success of the index pregnancy. These patterns suggest early pregnancy health is susceptible to stress processing pathways that influence this immunologic control in the first six to eight weeks of pregnancy. In this review, we discuss the known mediating role of immune factors in the stressor-depression relationship. We also discuss how adversity experienced before the index pregnancy, or "pre-pregnancy" may influence these pathways, and subsequently influence early pregnancy health. There is a need to understand adversity, experienced before pregnancy, and mechanisms driving the effects of these experiences on pregnancy outcomes. This approach is a useful entry point for understanding racial inequities in pregnancy health through an understanding of differences in exposures to adversity. We hypothesize that spontaneous abortion involves cyclical changes within a woman's reproductive tract in response to stressors that are established well before a woman enters into pregnancy. Furthermore, we propose mechanisms that potentially drive weathering processes relevant to reproductive disparities. We also examine what is known about pre-pregnancy stress exposures associated with race, inequity, and adversity, and their potential impact on neuroendocrine and immune changes affecting early pregnancy risk.

Reducing fresh full term intrapartum stillbirths through leadership and accountability in a low-resource setting, Mpilo Central Hospital, Bulawayo, Zimbabwe

Background

Stillbirths are distressing to the parents and healthcare workers. Globally large numbers of babies are stillborn. A number of strategies have been implemented to try and reduce stillbirths worldwide. The objective of this study was to assess the impact of leadership and accountability changes on reducing full term intrapartum stillbirths.

Methods

Leadership and accountability changes were implemented in January 2016. This retrospective cohort study was carried out to assess the impact of the changes on fresh full term intrapartum stillbirths covering the period 6 months prior to the implementation date and 12 months after the implementation date. The changes included leadership and accountability. Fresh full term stillbirths (>37 weeks gestation) occurring during the intrapartum stage of labour were analysed to see if there would be any reduction in numbers after the measures were put in place.

Results

There was a reduction in the number of fresh full term intrapartum stillbirths after the introduction of the measures. There was a statistical difference before and after implementation of the changes, 50% vs 0%, P = 0.025. There was a reduction in the time it took to perform an emergency caesarean section from a mean of 30 to 15 min by the end of the study, a 50% reduction.

Conclusions

Clear and consistent clinical leadership and accountability can help in the global attempts to reduce stillbirth figures. Simple measures can contribute to improving perinatal outcomes.

Low-level environmental metals and metalloids and incident pregnancy loss

Environmental exposure to metals and metalloids is associated with pregnancy loss in some but not all studies. We assessed arsenic, cadmium, mercury, and lead concentrations in 501 couples upon trying for pregnancy and followed them throughout pregnancy to estimate the risk of incident pregnancy loss. Using Cox proportional hazard models, we estimated hazard ratios (HR) and 95% confidence intervals (CIs) for pregnancy loss after covariate adjustment for each partner modeled individually then we jointly modeled both partners' concentrations. Incidence of pregnancy loss was 28%. In individual partner models, the highest adjusted HRs were observed for female and male blood cadmium (HR=1.08; CI 0.81, 1.44; HR=1.09; 95% CI 0.84, 1.41, respectively). In couple based models, neither partner's blood cadmium concentrations were associated with loss (HR=1.01; 95% CI 0.75, 1.37; HR=0.92; CI 0.68, 1.25, respectively). We observed no evidence of a significant relation between metal(loids) at these environmentally relevant concentrations and pregnancy loss.