Linh Hoang, MD, PhD
Consider these facts:
- In the US, preeclampsia affects 3.4 percent of all pregnancies and is the cause of 15 percent (3 in 20) premature births.
- Preeclampsia and hypertensive disorders double the probability of an adverse effect on infants. Those who survive often experience long-term health problems, including cerebral palsy, chronic lung disease, blindness, and hearing loss.
- The rate of preeclampsia among US mothers has steadily risen by 25 percent over the past two decades. If left undetected in women, preeclampsia can develop into eclampsia, the more severe form that triggers seizures or convulsions, leading to death.
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—when she is well into her second trimester. However, recent advances in diagnostic testing are now enabling physicians to screen for preeclampsia in the first trimester. With early screening comes early intervention, which has been shown to reduce the prevalence of the condition.
Research shows that placental growth factor (PlGF) is the most discerning biochemical marker for preeclampsia, particularly early-onset preeclampsia. Therefore, measuring PlGF levels in maternal serum before 14 weeks, in combination with maternal history, mean arterial blood pressure, and uterine artery pulsatility index, can help accurately predict which women are at high risk much earlier in their pregnancies. The International Federation of Gynecology and Obstetrics released new evidence-based guidelines in May 2019 recommending all pregnant women be screened in the first trimester using this combined test method.
To truly reduce the risk of preterm preeclampsia, intervention and treatment are needed simultaneously. Today, administering low-dose aspirin (150 mg) is known as an effective intervention following first-trimester screening.
A randomized, placebo-controlled multi-national study (the ASPRE project), funded by the European Union, provides definitive evidence of aspirin’s ability to reduce the prevalence of preterm preeclampsia. During the three-year study, pregnant women were screened by maternal history, mean arterial pressure, uterine artery Doppler and placental growth factor levels 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, and early-onset preeclampsia was reduced by up to 82 percent.
The International Society of Ultrasound and Gynecology (ISUOG) now recommends low-dose aspirin as treatment, citing “convincing evidence” that it 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 health and that of their babies.
By shifting from symptomatic diagnosis to screening of preeclampsia, clinicians have an invaluable opportunity to improve maternal and fetal outcomes.