OBJECTIVE: To estimate the risk of stillbirth in a second pregnancy when previous stillbirth, preterm, and small-for-gestational age (SGA) births occurred in the previous pregnancy.
METHODS: This was a population-based cohort study in New South Wales Australia from 2002 to 2006. Singleton births in a first pregnancy were linked to a second pregnancy using data from the New South Wales Midwives Data Collection and the New South Wales Perinatal Death Database. Deaths were classified according to the Perinatal Mortality Classifications of the Perinatal Society of Australia and New Zealand. Crude and adjusted hazard ratios were estimated using a proportional hazards model.
RESULTS: Delivery of an SGA newborn in the first pregnancy was associated with increased risks of stillbirth in a second pregnancy (hazard ratio 1.73, 95% confidence interval [CI] 1.15–2.60) and risk was further increased with prematurity (hazard ratio 5.65, 95% CI 1.76–18.12). Stillbirth in a first pregnancy had a nonsignificant association with stillbirth in the second pregnancy (hazard ratio 2.03, 95% CI 0.60–6.90). For women aged 30–34 years, the absolute risk of stillbirth up to 40 completed weeks of gestation was 4.84 per 1,000 among women whose first pregnancy was a stillbirth and 7.19 per 1,000 among women whose first pregnancy was preterm and SGA.
CONCLUSION: Delivering an SGA and preterm neonate in a first pregnancy is associated with greater risks for stillbirth in a second pregnancy than delivering a previous stillbirth. All factors merit improved surveillance in a subsequent pregnancy, and research should address underlying factors common to all three outcomes.
LEVEL OF EVIDENCE: II
Risks of stillbirth in a second pregnancy are greater when the previous neonate was small for gestational age and preterm compared with a previous stillbirth.
From the Department of Neonatal Medicine, Royal Prince Alfred Hospital, Sydney School of Public Health and Sydney Medical School, the University of Sydney, and Perinatal Research, Kolling Institute of Medical Research, Sydney University, Royal North Shore Hospital, St Leonards, New South Wales, Australia.
See related editorial on page 495.
Camille Raynes-Greenow was supported by a National Health and Medical Research Council postdoctoral fellowship.
The authors thank Lee Taylor and the Centre for Epidemiology and Research at the New South Wales Department of Health for providing the MDC and perinatal death data. They also thank the Centre for Health Record Linkage for performing probabilistic record linkage of the data sets.
Corresponding author: Adrienne Gordon, MBChB, MRCP, FRACP, MPH (Hons), Department of Neonatal Medicine, Royal Prince Alfred Hospital, Missenden Road, Camperdown, Sydney, NSW 2050, Australia; e-mail: email@example.com.
Financial Disclosure The authors did not report any potential conflicts of interest.