• Posted April 10, 2023

Induced Deliveries Could Help Prevent a Major Complication of Pregnancy

A potentially dangerous complication of pregnancy might be prevented by carefully screening women late in pregnancy and planning a timed delivery for those at high risk, a new study reports.

More than half of all preeclampsia cases that occur late in pregnancy could be warded off through induced labor or cesarean section provided to high-risk women, according to an analysis published online April 10 in the journal Hypertension.

Analysis of more than 86,000 pregnancies at two U.K. hospitals revealed that more than 57% of at-term preeclampsia cases could be avoided through screening and timed delivery, the researchers said.

"The approach that we outline in our study represents personalized medicine in maternity care, tailoring care to risk,"said lead researcher Dr. Laura Magee, a professor of women's health at King's College London.

"This means that those most likely to benefit from intervention are offered timed birth, by labor induction or elective cesarean, as they wish,"Magee continued. "Importantly, those least likely to benefit from intervention are observed and await spontaneous onset of labor, unless problems arise."

Preeclampsia is a sudden spike in blood pressure that occurs during pregnancy, according to the U.S. National Institutes of Health (NIH).

Women who develop preeclampsia are at increased risk for organ damage or failure, stroke, seizures and coma, the NIH says.

In addition, the mother's high blood pressure reduces blood supply to the fetus, increasing risk of preterm birth and stillbirth.

Preeclampsia occurs in 2% to 4% of pregnancies, the study authors said in background notes.

At least 75% of all preeclampsia cases take place when a woman is considered at-term and ready to deliver, between weeks 37 and 42 of pregnancy, the researchers noted.

Magee and her colleagues decided to see if there are enough telltale signs of preeclampsia either early or late in pregnancy that doctors could determine the women at highest risk for the complication.

"Preeclampsia is a condition with many risk factors, making prediction of preeclampsia more complex than one would hope. The approach that is used most commonly is a count of clinical risk factors, such as preeclampsia in a previous pregnancy or an underlying health condition such as chronic hypertension or diabetes,"Magee said.

"However, using only medical history misses most of the women who will develop preeclampsia, before or at-term gestational age. To pick up most of the women who will develop preeclampsia, one requires additional information,"she continued.

The analysis revealed the best way to identify women who will develop preeclampsia at-term is to screen them just before term, at 35 or 36 weeks of pregnancy.

A combination of personal history, blood pressure, and two blood tests that reflect blood vessel health were found to be the best means of screening for preeclampsia in this analysis, Magee said.

Women at highest risk could then undergo induced labor or a C-section before they develop preeclampsia, said Dr. Vesna Garovic, a professor with the Mayo Clinic in Rochester, Minn., and chair of the American Heart Association's scientific statement on hypertension in pregnancy.

"Basically, you attempt to deliver a patient in a pre-symptomatic phase, before the clinical presentation fully emerges,"Garovic said, commenting on the study.

In the study, 619 cases of at-term preeclampsia occurred in more than 29,000 pregnancies screened at 35 or 36 weeks' gestation.

Screening would have prevented 354 (57%) of those cases, the researchers reported.

However, screening at 11 to 13 weeks of gestation prevented just an estimated third of at-term preeclampsia cases, making it an "inferior"option compared to late-pregnancy screening, the findings showed

This is one of the first attempts to try to use a combination of clinical data and blood tests to predict a woman's risk of preeclampsia, Garovic said.

Screening could cut the risk of at-term preeclampsia in half, but close to 10 induced births might be necessary to prevent just one case of preeclampsia, she noted.

"Thus, further research is needed to better understand maternal and fetal benefits and safety,"Garovic said.

Both Garovic and Magee said the risks of timed delivery generally are those associated with preterm delivery, based on how long the fetus has gestated.

"In preeclampsia, the decision to pursue with labor induction is made by carefully weighing risks of maternal and fetal complications if pregnancy is further continued versus those of birth induction and prematurity,"Garovic said.

While doctors figure out the best way to screen for preeclampsia, women can take steps now to lower their risk during pregnancy, she added.

"To prevent preeclampsia, young women of reproductive age need to acquire a healthy lifestyle, including exercise, healthy diet, smoking cessation, and weight reduction,"Garovic said. "Regular obstetric visits and blood pressure monitoring can facilitate early diagnosis of preeclampsia, and may be of particular importance for those at elevated risks."

More information

The U.S. National Institutes of Health has more about preeclampsia.

SOURCES: Laura Magee, MD, professor, women's health, King's College London, United Kingdom; Vesna Garovic, MD, PhD, professor, Mayo Clinic, Rochester, Minn.; Hypertension, April 10, 2023, online