Birth defects lead to more stillbirths
Study shows many women terminate the pregnancy late
Canada’s stillbirth rate appears to be rising not because more fetuses are dying spontaneously but because more pregnancies are being terminated due to serious birth defects, researchers are reporting.
After decades of decline, rates of stillbirth — defined as the death of a fetus after 20 weeks’ gestation or when it weighs more than 500 grams — have increased in recent years in several countries, including in Canada, researchers wrote in this week’s issue of the Canadian Medical Association Journal. The question is, why? “The prevention of stillbirth through early delivery of the compromised fetus is considered the cornerstone of modern obstetrics,” the researchers wrote, and any sudden change in the trend is worrying. Some have speculated the increase in stillbirths could be due to more older mothers, or multiple births from fertility treatments.
But another explanation is pregnancy terminations for severe birth defects — therapeutic abortions “which can result in a fetal death that satisfies the current definition of a stillbirth,” the authors wrote.
“Historically, stillbirths that occur later on in pregnancy usually occur because of some pregnancy complication, meaning there is a problem with (the mother’s) health or a problem with fetal health,” said author Dr. K.S. Joseph, a professor in the department of obstetrics and gynecology at the University of British Columbia, as well as at the university’s School of Population and Public Health. Stillbirth rates had been declining because of improvements in detecting and managing problems during pregnancy. “If the rate of stillbirth is high, that’s a problem.”
In an attempt to explain the “unexpected phenomenon,” Joseph and his co-authors looked at data on all stillbirths of 20 weeks’ gestation or older in the province of B.C. from 2000 to 2010.
Overall, a total of 461,083 live births and 3,991 stillbirths were registered during the 10-year study period in the database of Perinatal Services BC.
The rate of recorded stillbirths increased 31 per cent, from 8.08 per 1,000 total births, to 10.55 per 1,000 births by 2010.
Next they looked at stillbirths according to whether they were spontaneous or resulted from a termination.
Spontaneous stillbirth rates have not increased. Instead, “what we found was that the increase in stillbirths seems to be because we have more acceptance and uptake of prenatal diagnosis and pregnancy termination for congenital anomalies,” Joseph said.
Fetal screening starting at around 18 weeks’ gestation can detect major chromosomal abnormalities as well as serious malformations of the brain and spine, such as anencephaly, a condition where most of the brain is missing, and complex heart defects. With anencephaly, “that would be a very straightforward decision to terminate the pregnancy, because that’s incompatible with survival,” Joseph said. “The baby may be born alive, but it cannot live because it doesn’t have a brain.”
If the pregnancy isn’t terminated, the baby can die in the womb. But the other possibility is that the baby is born alive, and then dies.
But if termination occurs after 20 weeks, it gets classified as a stillbirth. “So this is adding to our stillbirth rate.”