Novel strategies to prevent stillbirth

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Abstract

This article reviews three new and emerging risk factors for stillbirth that may be modifiable or might identify a compromised fetus. We focus on fetal movements, maternal sleep, and maternal diet. Recent studies have suggested than a sudden increase in vigorous fetal activity may be associated with increased risk of stillbirth. We review the papers that have reported this finding and discuss the implications as well as potential future directions for research. There is emerging literature to suggest that maternal sleep position may be a risk for stillbirth, especially if the woman settles to sleep supine. This risk is biologically plausible. How this knowledge may be utilized to assist stillbirth reduction strategies is discussed. Finally, we examine the somewhat limited literature regarding maternal diet and pregnancy outcome. Introducing probiotics into the diet may prove useful, but further work is required. The possible next steps for research are considered, as well as some potential intervention strategies that may ultimately lead to stillbirth reduction.

Introduction

There are a wide range of established risk factors for stillbirth; however, most of these risk factors have modest effect sizes and may not be modifiable once the woman is pregnant. Additionally, the findings from the large Stillbirth Collaborative Network Study [1], a case–control study, found that established risk factors such as ethnicity, gestational diabetes, smoking, drug addiction, overweight/obesity, accounted for little of the variance between cases and controls (19%). Thus to achieve a major stillbirth reduction in high-income countries it is necessary to ‘think outside the box’ and explore novel risk factors. If these novel risk factors are found to be associated with stillbirth, primary prevention strategies might be developed.

In this review we focus on three more recently explored risk factors for stillbirth that may be modifiable or might identify a compromised fetus: increased fetal movements, maternal sleep, and maternal diet. We also consider possible next steps for research as well as some potential intervention strategies that may ultimately lead to stillbirth reduction.

Section snippets

Increased fetal movements

Maternal perception of reduced fetal movements has long been associated with increased risk of small for gestational age infants, fetal growth restriction (FGR), and stillbirth [2], [3], [4]. However, there is emerging evidence to suggest that an increase in fetal movement (particularly if this is sudden) is also associated with stillbirth, with four recent studies reporting this.

The first to report this was a case–control study from New Zealand. Stacey et al. recruited 155 women who

Intervention

Studies reporting the potential association between a single episode of vigorous fetal movement and stillbirth are recent; however, as this has been found in four separate studies we would argue that care providers should consider their response when women report an episode of vigorous fetal movements described using words like “crazy”. International clinical practice guidelines with respect to management of pregnant women perceiving absent or reduced fetal movements recommend that these women

Where to from here?

It is feasible that women could be educated about extremes of fetal activity, rather than RFM, alone and that an episode of sudden increased fetal movement could be managed in the same way as a decrease; however, as shown in a recent systematic review, there are currently no proven strategies for the investigation and management of women presenting with decreased fetal movement [12]. Nevertheless, earlier studies have demonstrated a reduction in stillbirth numbers associated with maternal

Maternal sleep

Maternal sleep is a novel and relatively unexplored factor in stillbirth research. It is only in the past decade that intense interest in maternal sleep and pregnancy outcomes has occurred. This is somewhat surprising since sleep is an essential component of health; it consumes approximately one-third of human existence, yet poor sleep can severely impair the other two-thirds. In 2011, a meta-analysis of stillbirth risks [18] reported a number of important and potentially modifiable risk

Potential interventions

If supine sleep position is a potential fetal stressor, then avoidance (or minimization) of this sleep position might be one strategy to reduce stillbirth risk. It could be assumed that supine sleep is infrequent in late pregnancy due to maternal discomfort; however, the majority of women spend some time asleep on their back [79]. Importantly, of those who do have supine sleep, the median duration is about one-quarter of their sleep period. This constitutes a significant amount of time during

Where to from here?

Whereas further case–control studies will provide additional data either in support – or otherwise – of the emerging findings regarding the role of maternal supine sleep in stillbirth, other studies are currently in progress to determine whether positional intervention can significantly reduce or eliminate the proportion of time pregnant women spend in the supine sleep position. Whereas small, objective studies are feasible and will shed light on whether positional devices are useful and

Diet

Examination of the role of diet as it relates to stillbirth is complex, as macronutrients, micronutrients, dietary patterns, vitamins, trace elements, and essential fatty acids all need to be considered.

A Cochrane review of “Antenatal dietary education and supplementation to increase energy and protein intake” found clear evidence that the risk of stillbirth was significantly reduced for women given a balanced energy and protein supplementation [relative risk (RR): 0.60; 95% CI: 0.39–0.94; five

Intervention

Even if a dietary intervention could be found, it is probably too late to do much about altering the diet once the woman is pregnant. Therefore education would need to start before the woman became pregnant. As overweight/obesity is an established risk factor for stillbirth, advice to reduce weight before getting pregnant may be important.

Conclusions

The recent stillbirth priority-setting partnership mentioned in the Introduction identified eleven relevant research priorities. This review considers evidence and intervention strategies for three of these, namely:

  • 1.

    Do modifiable ‘lifestyle’ factors (e.g. diet, vitamin deficiency, sleep position, SDB) cause or contribute to stillbirth risk?

  • 2.

    Which antenatal care interventions are associated with a reduction in the number of stillbirths?

  • 3.

    Would more accessible evidence-based information on signs and

Conflict of interest statement

None declared.

Funding sources

None.

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