Women who have experienced a stillbirth have up to a fourfold increased risk of stillbirth in a second pregnancy compared to those who had an initial live birth, finds a new major review of research, carried out by scientists at the University of Aberdeen and published in The BMJ this week.
Stillbirth rates have declined across most of Europe, but the UK still has a major public health problem. Ranked 33rd out of 35 for stillbirth rates among European countries, the UK recorded 3,286 stillborn babies in 2013.
"Stillbirth is one of the most common adverse obstetric outcomes and a traumatic experience for parents," explain Dr Sohinee Bhattacharya and colleagues from the University of Aberdeen, Scotland. "Couples who have experienced a stillbirth need to understand why it happened and want to know the risk for future pregnancies."
But there has not been sufficient information for the clinical management or to improve prevention of this traumatic outcome, they say.
Researchers undertook systematic review and meta-analysis to examine the link between stillbirth in an initial pregnancy and risk of stillbirth in a subsequent pregnancy.
They analysed 13 cohort and three case-control studies from high-income countries including Australia, Scotland, the US, Denmark, Israel, the Netherlands, Norway and Sweden.
The definition of stillbirth was fetal death at more than 20 weeks’ gestation or a birth weight of at least 400g.
Data was collected for 3,412,079 women. Of these, 3,387,538 (99.3%) women had a previous live birth and 24,541 (0.7%) women had a stillbirth in an initial pregnancy.
Stillbirths occurred in the subsequent pregnancy for 14,283 women: 606 of 24,541 (2.5%) in women with a history of stillbirth and 13,677 of 3,387,538 (0.4%) in women with no history.
Twelve studies assessed the risk of stillbirth in second pregnancies. Analyses showed that women who had a stillbirth in an initial pregnancy had a nearly fivefold increased risk of stillbirth in a second pregnancy. This risk is higher than stillbirth linked with medical conditions such as diabetes or hypertension.
After adjusting for confounding factors such as maternal age, maternal smoking and level of deprivation, the increased risk was up to fourfold higher.
Risks following an unexplained stillbirth may not be increased because there are few studies and the evidence remains inadequate, explain the authors.
Pre-pregnancy counselling services should be provided to women who had a stillbirth, they urge, as well as advice on changing these lifestyle factors such as smoking and obesity that are both linked to an increased risk of stillbirth.
Pregnancies should be closely monitored, and antenatal interventions and care be offered at the first sign of increased risk of distress or danger, they add.
In a linked editorial, experts from St Mary's Hospital echo calls for additional care in next pregnancy, and for more research on unexplained stillbirths, which can account for around 20% of stillbirths. In addition, they stress the importance of an improved international classification system to determine causes of death, especially as these can be quite complex, so that interventions can be adequately targeted.