Problems with placenta to blame for small babies, while maternal diabetes, obesity can mean large babies
Foetuses at the extremes of weight – either very small or very large – have a greater risk of being stillborn than babies of more average weight, a new study indicates.
Researchers from St. Michael's Hospital in Ontario examined records of about 767,000 live births and nearly 4,700 stillbirths that occurred in Ontario between 2002 and 2007. Stillbirth is typically defined as a foetus that dies at the 23rd week of gestation or later and weighing at least 0.5kg, though this research included foetuses that died at 20 weeks or later.
About 19% of stillbirths occurred in foetuses below the tenth percentile for weight, meaning they are smaller than 90% of foetuses.
Smallest foetuses face bigger risk
The smallest foetuses faced an even bigger risk. Being among the smallest 1% put foetuses at a nearly 10 times higher risk of stillbirth than average weight babies, or those in the 40th to 60th weight percentiles.
Very large foetuses also faced some added risks. About 1% of stillbirths occurred among foetuses in the top 1% for weight.
"In this study of all registered live-born and stillborn infants in Ontario, extreme underweight and overweight states confer the highest risk of stillbirth," study authors Drs Joel Ray and Marcelo Urquia, said in a hospital news release.
Small foetuses are often due to a faulty placenta, while maternal diabetes and obesity often leads to very large foetuses. The rate of stillbirth in industrialised countries is about six per 1,000.
The study was published in the Journal of Perinatology.
(HealthDay News, June 2012)
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