Tomasina Stacey

Association between maternal sleep practices and risk of late stillbirth: a case-control study

Objectives To determine whether snoring, sleep position, and other sleep practices in pregnant women are associated with risk of late stillbirth. Design Prospective population based case-control study. Setting Auckland, New Zealand Participants Cases: 155 women with a singleton late stillbirth (≥28 weeks’ gestation) without congenital abnormality born between July 2006 and June 2009 and booked to deliver in Auckland. Controls: 310 women with single ongoing pregnancies and gestation matched to that at which the stillbirth occurred. Multivariable logistic regression adjusted for known confounding factors. Main outcome measure Maternal snoring, daytime sleepiness (measured with the Epworth sleepiness scale), and sleep position at the time of going to sleep and on waking (left side, right side, back, and other). Results The prevalence of late stillbirth in this study was 3.09/1000 births. No relation was found between snoring or daytime sleepiness and risk of late stillbirth. However, women who slept on their back or on their right side on the previous night (before stillbirth or interview) were more likely to experience a late stillbirth compared with women who slept on their left side (adjusted odds ratio for back sleeping 2.54 (95% CI 1.04 to 6.18), and for right side sleeping 1.74 (0.98 to 3.01)). The absolute risk of late stillbirth for women who went to sleep on their left was 1.96/1000 and was 3.93/1000 for women who did not go to sleep on their left. Women who got up to go to the toilet once or less on the last night were more likely to experience a late stillbirth compared with women who got up more frequently (adjusted odds ratio 2.28 (1.40 to 3.71)). Women who regularly slept during the day in the previous month were also more likely to experience a late stillbirth than those who did not (2.04 (1.26 to 3.27)). Conclusions This is the first study to report maternal sleep related practices as risk factors for stillbirth, and these findings require urgent confirmation in further studies.

Maternal Perception of Fetal Activity and Late Stillbirth Risk: Findings from the Auckland Stillbirth Study

BACKGROUND   Maternal perception of decreased fetal movements has been associated with adverse pregnancy outcomes, including stillbirth. Little is known about other aspects of perceived fetal activity. The objective of this study was to explore the relationship between maternal perception of fetal activity and late stillbirth (≥28 wk gestation) risk. METHODS   Participants were women with a singleton, late stillbirth without congenital abnormality, born between July 2006 and June 2009 in Auckland, New Zealand. Two control women with ongoing pregnancies were randomly selected at the same gestation at which the stillbirth occurred. Detailed demographic and fetal movement data were collected by way of interview in the first few weeks after the stillbirth, or at the equivalent gestation for control women. RESULTS   A total of 155/215 (72%) women who experienced a stillbirth and 310/429 (72%) control group women consented to participate in the study. Maternal perception of increased strength and frequency of fetal movements, fetal hiccups, and frequent vigorous fetal activity were all associated with a reduced risk of late stillbirth. In contrast, perception of decreased strength of fetal movement was associated with a more than twofold increased risk of late stillbirth (aOR: 2.37; 95% CI: 1.29-4.35). A single episode of vigorous fetal activity was associated with an almost sevenfold increase in late stillbirth risk (aOR: 6.81; 95% CI: 3.01-15.41) compared with no unusually vigorous activity. CONCLUSIONS   Our study suggests that maternal perception of increasing fetal activity throughout the last 3 months of pregnancy is a sign of fetal well-being, whereas perception of reduced fetal movements is associated with increased risk of late stillbirth.

The Auckland Stillbirth study, a case-control study exploring modifiable risk factors for third trimester stillbirth: methods and rationale.

Background:  In high‐income countries, stillbirth rates have been static in recent decades. Unexplained stillbirths account for up to 50% of these deaths.

Fetal growth restriction and other risk factors for stillbirth in a New Zealand setting

Background:  Stillbirth affects almost 1% of pregnant women in the Western world but is still not a research priority.

Antenatal care, identification of suboptimal fetal growth and risk of late stillbirth: findings from the Auckland stillbirth study

Stillbirth remains an important public health problem in Australia and New Zealand. The role that antenatal care plays in the prevention of stillbirth in high‐income countries is unclear.

Maternal knowledge of fetal movements in late pregnancy

Current evidence suggests that fetal movements are an important indicator of fetal well‐being. About a quarter of women who present with decreased fetal movements have adverse perinatal outcomes such as intrauterine growth restriction and stillbirth. There are no New Zealand studies reporting maternal knowledge about fetal movements in late pregnancy.

Sleep position and risk of late stillbirth

Obesity is an established risk factor for stillbirth, however the reason for this is not known. There are several possible mechanisms which have not previously been investigated, such as maternal and fetal hypoxia from adverse maternal sleep position or sleep disordered breathing (SDB). We hypothesised: 1. that obesity is an independent risk factor for stillbirth, 2. that after adjustment for established risk factors for stillbirth, the higher rates in Maori and Pacific Island babies are no different to that of European babies, and 3. that sleep disordered breathing is a risk factor for stillbirth, and that this (at least in part) explains the increased risk with obesity. The Auckland stillbirth study was a case control study conducted in Auckland, New Zealand between 2006 and 2009 [1]. In this study, we explored potentially modifiable risk factors for late stillbirth, including maternal position on going to sleep [2]. We found that maternal non-left position on going to sleep (on the last night prior to stillbirth, or prior to interview) was associated with a two fold increase in late stillbirth adjusted odds ratio (aOR) 2.0 (95% confidence interval (CI): 1.2 to 3.3) [2]. The greatest effect was when the mother went to sleep on her back (aOR 2.5, 95% CI: 1.0 to 6.2) and intermediate when on the right (aOR 1.7 95% CI: 1.0 to 3.0). These findings remained significant after adjustment for known confounders such as maternal body mass index, age and smoking. Although we could not establish an association between SDB (measured using self reported snoring and daytime sleepiness) and risk of stillbirth, these symptoms are common in pregnancy and may not identify true SDB. This is the first time that an association between maternal sleeping position and risk of late stillbirth has been described and therefore the finding should be interpreted with some caution until further studies have confirmed or refuted it. There is, however, some evidence that may support the biological plausibility of such an association, as maternal body position has been found to impact on maternal and fetal physiological parameters. Specifically it has been shown that maternal cardiac output in late pregnancy is greatest in the left lateral position, intermediate in the right lateral position and lowest when the mother is supine [3]. Similar graded effects have been found between fetal oxygenation in labour and maternal position, with optimum oxygen levels recorded with the mother on her left side [4]. This is speculated to be due to the anatomy of the lower abdomen and the potential compression of the aorta and inferior vena cava caused by the weight of the uterus and growing fetus when the woman is in either the supine position or in the right lateral position. The absolute risk of late stillbirth for women who went to sleep on their left side was 1.96/1000 and was 3.93/1000 for women who did not go to sleep on their left. This study identified a potentially modifiable risk factor for stillbirth, but confirmatory studies are needed before public health recommendations can be made.

Uptake of the Perinatal Society of Australia and New Zealand perinatal mortality audit guideline

Background:  Deficiencies in investigation and audit of perinatal deaths result in loss of information thereby limiting strategies for future prevention. The Perinatal Society of Australia and New Zealand (PSANZ) developed a clinical practice guideline for perinatal mortality in 2004.

Association between maternal sleep practices and late stillbirth – findings from a stillbirth case‐control study

To report maternal sleep practices in women who experienced a stillbirth compared with controls with ongoing live pregnancies at similar gestation.

Going to sleep in the supine position is a modifiable risk factor for late pregnancy stillbirth; findings from the New Zealand multicentre stillbirth case-control study

Objective Our objective was to test the primary hypothesis that maternal non-left, in particular supine going-to-sleep position, would be a risk factor for late stillbirth (≥28 weeks of gestation). Methods A multicentre case-control study was conducted in seven New Zealand health regions, between February 2012 and December 2015. Cases (n = 164) were women with singleton pregnancies and late stillbirth, without congenital abnormality. Controls (n = 569) were women with on-going singleton pregnancies, randomly selected and frequency matched for health region and gestation. The primary outcome was adjusted odds of late stillbirth associated with self-reported going-to-sleep position, on the last night. The last night was the night before the late stillbirth was thought to have occurred or the night before interview for controls. Going-to-sleep position on the last night was categorised as: supine, left-side, right-side, propped or restless. Multivariable logistic regression adjusted for known confounders. Results Supine going-to-sleep position on the last night was associated with increased late stillbirth risk (adjusted odds ratios (aOR) 3.67, 95% confidence interval (CI) 1.74 to 7.78) with a population attributable risk of 9.4%. Other independent risk factors for late stillbirth (aOR, 95% CI) were: BMI (1.04, 1.01 to 1.08) per unit, maternal age ≥40 (2.88, 1.31 to 6.32), birthweight <10th customised centile (2.76, 1.59 to 4.80), and <6 hours sleep on the last night (1.81, 1.14 to 2.88). The risk associated with supine-going-to-sleep position was greater for term (aOR 10.26, 3.00 to 35.04) than preterm stillbirths (aOR 3.12, 0.97 to 10.05). Conclusions Supine going-to-sleep position is associated with a 3.7 fold increase in overall late stillbirth risk, independent of other common risk factors. A public health campaign encouraging women not to go-to-sleep supine in the third trimester has potential to reduce late stillbirth by approximately 9%.