Miscarriage is one of the most common complications in early pregnancy, affecting around one in every four pregnancies. Now, researchers say they have identified the molecules that could predict the risk of these complications, long before the symptoms show up and it’s too late.
Also known as spontaneous abortion, a miscarriage is defined as the spontaneous loss of a fetus before the threshold of viability. In the US, this threshold is defined as the 20th week of the pregnancy. However, most miscarriages happen during the first 13 weeks of gestation, and the risk of miscarriage declines after that period. This is why many women elect to keep their pregnancy private until after the 3-month period, after which the odds of miscarriage decreases and the odds of birth increases.
For the most part, women in the early stages of their pregnancy are in the dark as to their risk for miscarriage. Hoping to shed light on this risk, researchers in San Francisco searched for biomarkers associated with pregnancy complications.
The team from the Laboratory of Premature Medicine and Immunology in San Francisco didn’t focus on the obvious place: the placenta, an organ unique to pregnancy, and is responsible for nourishing the fetus. Instead, the team focused on a thick mucous membrane, rich in immune cells, that lines the uterus during pregnancy, known as the placental bed.
The team analyzed data from 160 births. Their search yielded 30 molecules, of the microRNA variety, that seemed to be associated with early pregnancy complications. In addition to miscarriage during the first three months, other complications included were preterm birth and preeclampsia, a life-threatening blood pressure disorder that often results in premature birth.
Briefly, the biomarkers were 90 percent accurate at predicting miscarriage and preeclampsia. For premature birth (before 34 weeks), the test was 89 percent accurate. For premature birth between 34 and 38 weeks, the test was 92 percent accurate.
For miscarriage, current treatment guidelines include preventing hemorrhaging and infection, and helping the woman manage pain and other symptoms. In some cases when the body does not expel the fetus naturally, a doctor may have to perform a procedure (dilation and curettage) to remove the tissues. These measures are aimed at preserving the health of the woman rather than the fetus. And while know the risks of a miscarriage may not alter the course of therapy, it could provide women more time to prepare for this traumatic experience.
On the other hand, complications like preterm birth and preeclampsia could be managed with medical intervention. In such events, women would greatly benefit from early detection, as it would allow more time for preventative measures.
“Our combined analysis supports the idea that the Great Obstetrical Syndromes have a common biological origin early in the first trimester that can be detected throughout the first trimester using peripheral blood cell microRNA,” the researchers said.
The study was presented at the 2017 American Association of Reproductive Medicine annual congress in Texas, and included data over a series of four published studies.
Additional sources: BBC