Late stillbirth: the contribution of maternal sleep practices and maternal views

Abstract

Three babies are stillborn in the third trimester of pregnancy each week in New Zealand, a rate of 2.4/1000 births. The 2016 Lancet stillbirth series highlighted differences in the rates of late stillbirth (≥28 weeks’ gestation) between high-income countries, ranging from 1.7 to 8.8/1000 births, suggesting that a reduction in countries with higher rates is possible. The aim of this PhD thesis is to add to the existing knowledge on potentially modifiable risk factors for late stillbirth in New Zealand to assist in reducing this tragedy in the future. The Auckland Stillbirth Study, published in 2011, was the first to identify an association between maternal supine going-to-sleep position and late stillbirth. This provided an important stimulus for further studies on sleep position and stillbirth. We pooled the eligible studies into an individual participant data metaanalysis, concluding that supine going-to-sleep position should be considered a contributing factor for late stillbirth in all pregnancies. We also hypothesised that supine going-to-sleep position may interact with other sleep factors to magnify the risk of stillbirth. Potential relationships were investigated in a secondary analysis. Sleep duration >9 hours and daily daytime naps in the last month were found to be independently associated with increased risk of late stillbirth, however, sleep that was more restless than average was associated with reduced risk. To support the translation of our research into practice, women’s views on third trimester sleep were surveyed. Women reported that they could modify their going-to-sleep position. This suggested that a public awareness campaign on late pregnancy going-to-sleep position was feasible. Our New Zealandwide campaign commenced in 2018. As women’s involvement in stillbirth research is essential to achieve research outcomes, we also surveyed women’s views on participation. All women provided positive feedback. Understanding why late stillbirths occur may contribute to risk reduction. We asked the women who were stillbirth cases about their decision-making for post-mortem examination for their babies. Our findings of possible emotional benefits from the decision for a full post-mortem examination have now been incorporated into national perinatal post-mortem information. This thesis has added a New Zealand perspective to the existing literature on late stillbirth. It has identified novel factors that present new possibilities for further research and future reductions in the incidence of late stillbirth.