TORONTO - Using a combination of simple, non-invasive tests early in pregnancy can determine whether a woman has placental damage that could lead to stillbirth or a severely underweight, premature baby, a Canadian study has found.
Researchers at Mount Sinai Hospital in Toronto say standard blood tests for Down syndrome and spina bifida, along with ultrasounds, can be used to detect a damaged placenta, the lifeline that allows oxygen, nutrients and antibodies to flow from the mother to her developing fetus.
Principal investigator Dr. John Kingdom, a maternal-fetal medicine specialist, said that having the tests can reassure most high-risk mothers-to-be that their placenta is formed and functioning properly, so they can expect a healthy pregnancy.
And for those women whose results are abnormal, the early timing of the tests - at 16 to 23 weeks gestation - means doctors can intervene to try to improve the pregnancy's outcome.
"Close to 40 per cent of high-risk mothers we see in our clinic experience placental damage," said Kingdom. "By identifying early on if there is a potential risk of complications, we can do everything possible to ensure the safety of both the mother and fetus."
Placental abnormalities can lead to a variety of undesirable outcomes, including life-threatening pre-eclampsia (maternal high blood pressure), stillbirth or premature delivery.
Kingdom said screening procedures include: tests to measure levels of a specific protein in the mother's blood to detect signs of possible Down syndrome or spina bifida; a uterine artery Doppler flow test, which checks maternal blood flow in the placenta; and an ultrasound to check the shape of the placenta.
"This strategy allows us to identify women that we should study to try to prevent placental damage," Kingdom said in an interview. "The first way to prevent it is to diagnose it."
"We've never before had the mental strategy that we should make a diagnosis of placental insufficiency in pregnancy," he said, noting that the diagnosis is often made after the fact, for instance, when a woman loses her baby and pre-eclampsia is found to have been the cause.
"We're passionate about trying to make a difference here in these common conditions and the way we're making a difference is: Here's a way of making the diagnosis during pregnancy before the baby's damaged."
To determine how well the combination of tests works in detecting placental damage, the researchers studied 212 women, aged 19 to 44, with high-risk pregnancies. (A high-risk pregnancy may occur because of several conditions in the mother, including chronic high blood pressure, diabetes and obesity.)
Nineteen of the women delivered pre-term babies due to poor fetal growth; all had abnormal placental function tests, say the researchers, whose paper is published in the April issue of the American Journal of Obstetrics and Gynecology.
Another 22 women had stillbirths, 20 of them due to placental abnormalities that were picked up by the tests. The two remaining women with stillbirths had normal test results; their babies did not survive because of infections unrelated to the placenta. Of 35 women who developed pre-eclampsia, 26 had at least one abnormal test result.
If the placenta is damaged, doctors can try a number of interventions, including treating a woman's pre-eclampsia with blood pressure-lowering drugs, Kingdom said. For a women whose fetus has poor growth, giving steroid injections can strengthen the infant's lungs in preparation for a premature delivery.
The Society of Obstetricians and Gynecologists of Canada says premature labour is one of the most common problems in pregnancy and the cause of 75 per cent of all newborn deaths in babies born without birth defects.
"Premature babies are more delicate and can have lifelong problems related to their prematurity," the society says on its website. "In general, the more premature a baby is, the more severe the problems. Babies born before the 25th week usually do not survive without problems."
Because placental insufficiency may be associated with clots that disrupt blood flow to the temporary pregnancy-related organ, the researchers have begun a new study to see if the blood-thinning drug heparin could prevent further damage and improve the chances of a healthy, full-term baby.
