Predict and Prevent: A New Approach to Screening for Pre-term Preeclampsia
JANUARY 31, 2019
Linh Hoang, MD, PhD
Linh Hoang, MD, PhDAccording to data from the National Center for Health Statistics, the rate of preterm births increased from 9.85% in 2016 to 9.93% in 2017, marking the second consecutive year of a rise in preterm births. Preeclampsia, a condition characterized by high blood pressure during pregnancy, which restricts blood flow to the placenta—resulting in delivery of the baby before 37 weeks’ gestation—is a maternal health condition commonly associated with preterm births.
In the US today, preeclampsia is the cause of 15% of premature babies born, and globally, approximately 500,000 infants will die each year as a result of this condition and related hypertensive disorders. Those who survive often experience long-term health problems, including cerebral palsy, chronic lung disease, blindness and hearing loss. The risk for mothers is equally dire: If left undetected, preeclampsia can develop into eclampsia, the more severe form that triggers seizures or convulsions, leading to death.
Although the exact cause of preeclampsia is widely debated, the rate of preeclampsia among US mothers has risen by 25% over the past 2 decades. The condition is responsible for causing an estimated 13% of worldwide maternal deaths (equating to 1 mother every 12 minutes). What many are unaware of, though, is that early screening exists to predict preeclampsia, and early intervention has been shown to reduce its prevalence.
Traditional preeclampsia screening is based on the mother’s health history, as well as incidence of elevated blood pressure (≥140/90 mmHg) occurring after 20 weeks of pregnancy. At that point, though, a woman is well into her second trimester. Because the treatment for preeclampsia is delivery, she must be closely monitored—and sometimes placed on bed rest or hospitalized—to avoid further complications, including preterm birth.
From Diagnose and Manage, to Predict and Prevent
But recent advances in diagnostic testing are now enabling physicians to screen in the first trimester. Research shows placental growth factor (PlGF) to be the most discerning biochemical marker for preeclampsia—particularly early onset preeclampsia. Therefore, measuring PlGF levels in maternal serum during the first trimester (before 14 weeks), in combination with maternal history, uterine artery pulsatility index (uTPI) and mean arterial blood pressure (MAP), can help accurately predict women who are at high risk much earlier in their pregnancies.
Shifting from symptomatic diagnosis, to screening of preeclampsia provides an opportunity to improve maternal and fetal outcomes. While having such foresight before symptoms appear is critical, intervention is also needed to effectively reduce the risk of preterm preeclampsia and to help ease the devastating maternal and fetal mortality rates brought about by it.
Today, administering low-dose aspirin (150 mg) is shown to be an effective intervention following first-trimester screening. A randomized, placebo-controlled multi-national study (the ASPRE project), funded by the European Union, provided definitive evidence of aspirin’s ability to reduce the prevalence of preterm preeclampsia.
With Early Screening Comes Early Intervention
During the three-year study, screening by maternal history, mean arterial pressure, uterine artery doppler and placental growth factor levels occurred between 11-13 weeks’ gestation, and optimal results were achieved when low-dose aspirin (150 mg) treatment started before 16 weeks. With treatment, the preterm preeclampsia (< 37 weeks) incidence was reduced by as much as 62% percent in women.
The International Society of Ultrasound and Gynecology (ISUOG) now recommends this treatment, citing “convincing evidence” that low-dose aspirin significantly decreases the risk for development of preterm preeclampsia “when administration commences at the time of first-trimester screening.”
ISUOG’s endorsement is a major step forward for the obstetrics field, as it not only reiterates the importance of timely screening, but also establishes the opportunity to offer women greater control over their own and their baby’s health.
The path to preventing preeclampsia is not ambiguous or complex. It is clear and simple: All women should be assessed in the first trimester of their pregnancy to identify the risk of preterm preeclampsia—regardless of medical history or other health factors. And, when it comes to risk assessment and treatment of preeclampsia, early screening is paramount to improving outcomes.
The Way Forward
With recent scientific research and new advances in diagnostic testing, physicians have the power to provide more accurate predictions and help patients make informed choices. By employing a “predict and prevent” approach to preterm preeclampsia, basic measures can be taken to significantly reduce the likelihood of developing preterm preeclampsia and ultimately protect the health of a mother and her child.
Linh Hoang, MD, PhD, is the Vice President of Reproductive Health at PerkinElmer. PerkinElmer, Inc. is a global leader in prenatal screening, helping expectant parents determine risk for pregnancy-related complications or disorders. The piece reflects his views, not necessarily those of the publication.
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