According to researchers at Yale School of Medicine in the United States, women who have a baby when they are aged 40 or over are three times more likely to experience a stillbirth.
The researchers say such women should have more checks for stillbirth.
The researchers also found that fetal testing at 38 weeks has the greatest impact at reducing stillbirth rates in older women.
Older pregnant women are at more risk for a number of complications in pregnancy including gestational diabetes mellitus, preeclampsia, placenta previa and intrauterine growth restriction and all of these conditions have been associated with a higher rate of stillbirth.
In order to find out if advance maternal age was an independent risk factor for stillbirth and when fetal testing would be most beneficial for reducing stillbirth rates, the researchers carried out a cross-sectional study using the United States CDC perinatal mortality database.
The database is made up of 11,061,599 singleton deliveries between 1995 and 1997; the women in the study were between 15 to 44 years of age and were at least 37 weeks pregnant.
When maternal complications and congenital abnormalities in the foetus were excluded, six million babies remained.
The researchers then looked at data from the U.S. Centers for Disease Control, which registered the deaths of babies.
They calculated that women aged 40 to 44 had three times the risk of stillbirth than women aged 25 to 29.
Lead author Dr. Mert Ozan Bahtiyar, a professor in the Department of Obstetrics, Gynecology & Reproductive Sciences at Yale School of Medicine, says the results of the study supports routine antenatal testing in those women who are over age 40, beginning at 38 weeks gestation; this he says will help identify women who are most at risk for stillbirth.
Such checks would include listening to the baby's heart-beat and testing the amniotic fluid to pick up any signs of distress.
A stillbirth occurs when a fetus which has died in the womb or during labour or delivery exits its mother's body and the term is often used in distinction to live birth or miscarriage.
The term "stillbirth" is used by some experts to describe a fetus which has died after reaching mid-second trimester to full term gestational age.
In the United Kingdom, "stillbirth" is used to describe an infant delivered without life after 24 weeks gestation and for a death which occurs earlier in development the term.
While 14 percent of fetal deaths occur during labour and delivery, 86 percent occur before labour begins.
A pregnant woman may suspect that something is wrong if the baby suddenly stops moving around and kicking.
Dr. Bahtiyar says any woman in that situation should not panic but, if they detect decreased foetal movement, they should contact their physician.
The research was presented to the Maternal-Fetal Medicine Conference being held in San Francisco.