Preeclampsia is a very serious high blood pressure condition that can arise during pregnancy and is a leading cause of maternal deaths. Defined as blood pressure greater or equal to 140/90 mm Hg, the condition affects as many as 1 in 25 pregnancies in the United States and complicates eight percent of births worldwide

It is typically diagnosed after 20 weeks of pregnancy and symptoms can include vision changes, headaches, and swelling in the hands, feet, face or eyes of the mother, or a change in the unborn baby’s well-being.  

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A study published April 10 in the journal Hypertension found that more than half of all preeclampsia cases that occurred during an at term birth (37 to 42 weeks) may be prevented with a timed birth. Timed birth methods include a labor induction with oxytocin or a surgical Cesarean section.

A preterm delivery may already be considered for patients who develop preeclampsia during weeks 20 to 36 of pregnancy, but most preeclampsia cases occur during 37 to 42 weeks gestation. “Timed birth is achievable in many hospitals or health centers,” study co-author and professor of obstetric medicine at King’s College in London Laura A. Magee said in a statement. “So our proposed approach to prevent at-term preeclampsia has huge potential for global good in maternity care.”

For the study, a team of researchers in the United Kingdom looked at more than 10 years of health records from King’s College Hospital in London and Medway Maritime Hospital in Gillingham. Most of the patients in the dataset were in their early 30s and self-identified as white. Roughly 10 percent self-identified as smokers and less than three percent had a medical history of high blood pressure, Type 2 diabetes, or an autoimmune disease. Only 3.9 percent reported any known family history of preeclampsia.

The dataset included 57,131 pregnancies with health records at 11 to 13 weeks gestation. Of these, there were 1,138 cases of at-term preeclampsia. In the 35 to 36 weeks timeframe, there were 619 cases of at-term preeclampsia.

The researchers evaluated the risk of preeclampsia and potential benefits of a timed birth for both groups, using the standard critical criteria for the condition and a risk prediction model that uses a patient’s individual factors to assess risks. 

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They found that at term preeclampsia occurred with a similar frequency when the patients screened during their first trimester to those screened during their third. On average, the patients included in the study delivered at 40-weeks. Two-thirds of all participants experienced spontaneous onset of labor and about one-fourth of the patients had Cesarean deliveries.

Additionally, their analysis indicates that when using a risk model in place of standard clinical screening, a timed birth may be an effective intervention for reducing the risk of at-term preeclampsia by more than half.

“Our findings suggest that over half of the cases of at-term preeclampsia may be prevented by timed (planned) birth,” said Magee. “It is important to note that being at higher risk of at-term preeclampsia was associated with earlier spontaneous onset of labor, so women at the highest risk were already less likely to deliver close to their due date.”

Some of the limitations of the research included that the preeclampsia risks were only calculated through risk modeling, and that the study didn’t look at the potential for preeclampsia after delivery which, while rare, can occur up to six weeks after birth.  Additionally, randomized clinical trials are needed to evaluate the safety and effectiveness of timed birth as an appropriate intervention to reduce at-term preeclampsia.

For pregnant people with risk factors, the Cleveland Clinic recommends some preventative steps to lower risk. These include managing blood pressure and blood sugar, getting enough sleep, and maintaining a regular exercise routine. Taking a baby aspirin daily also might decrease the risk of developing preeclampsia by 15 percent, according to the Cleveland Clinic.