Most at-risk women for preeclampsia not given recommended prevention

Women with pre-pregnancy diabetes, obesity or chronic hypertension are at high-risk of preeclampsia, but aren’t getting the prevention they need: baby Aspirin. While there are several additional risk factors for preeclampsia, these three common risk factors, alone or in combination, “represent those at highest risk in Canada,” said Dr. Joel Ray, a professor of medicine and obstetrics, University of Toronto. Yet, most of these women aren’t getting a simple, inexpensive and well-studied treatment to help prevent preeclampsia—low-dose Aspirin. And determining who is at risk is generally quite straightforward, he said. Read: No increased risk of congenital anomalies from statin use during pregnancy Dr. Ray was lead author of a paper in JAMA which examined how commonly low-dose Aspirin was given to pregnant women with any of these three high-risk conditions for preeclampsia prevention. The study was done as part of the Diabetes, Obesity, and Hypertension in Pregnancy Research Network (DOH-NET). Previous DOH-NET work showed that 11 per 1,000 Ontario births have pre-pregnancy diabetes; 178 per 1,000 obesity; and 11 per 1,000 have chronic hypertension. Moreover, about 5 per 1,000 births have both maternal diabetes and obesity; one per 1,000 diabetes plus hypertension; and six per 1,000 obesity and hypertension combined. The rate of all three together is 0.7 per 1,000. Dr. Ray noted that pre-pregnancy diabetes and chronic hypertension are ranked by the U.S. Preventive Service Task Force (USPSTF) guidelines as high-level risk factors, which tend to cluster in women with obesity. That, and other guidelines, such as those from the Association of Ontario Midwives, and the SOGC all endorse low-dose ASA prophylaxis in women with these and other risk factors. Other studies showed that only 7.6% of eligible women are prescribed low-dose Aspirin even though it is known to provide relative risk reductions against preeclampsia ranging from 10% to 50%, he said. For the new low-dose prophylaxis study, population-based data were obtained from the Better Outcomes Registry and Network (BORN) Ontario, a provincially mandated birth registry. Included were data for all women with a hospital live birth or stillbirth at 23-plus weeks’ gestation, from April 2018 to December 2020. The data included demographic information, clinical details, as well as a field about daily Aspirin use for preeclampsia prevention. Included were 77,582 women with pre-pregnancy diabetes, obesity and/or chronic hypertension—about 21% of all 371,237 women who gave birth. However, Aspirin was reported to be used in only 17.2% of women with diabetes, 6.9% in women with obesity, and 27.6% in women with hypertension. “Most of the women with pre-pregnancy diabetes have type 2 diabetes. Nevertheless, all women with pre-pregnancy diabetes mellitus are at higher risk of preeclampsia and preterm birth,” Dr. Ray said in an interview with the Medical Post. People seem to be more generally aware of aspirin use for cardiovascular disease in later adulthood, but there doesn’t appear to be as much awareness of its effective role in pregnancy. Aspirin use was still low in women who had at least two of the key risk factors together. Here, the rates of Aspirin use was only 22.2% in women who had both diabetes and obesity; 36.6% in women with diabetes and hypertension; 32.3% in women with obesity and hypertension, and 38.8% in women with all three risk factors. Large clinical trials have repeatedly shown that Aspirin safely reduces the risk of preeclampsia, preterm birth, intrauterine fetal growth restriction, and perinatal mortality, Dr. Ray said. The daily dose is one or two baby Aspirin (81 mg to 162 mg), starting at about 12 weeks’ gestation. If a woman is referred to an obstetrician, “by then, she is often too far along in the pregnancy to derive any benefit from aspirin,” he said. “Any practitioner who meets a woman in early pregnancy can know her past pregnancy and her current health status, and immediately decide if she is a candidate for low-dose Aspirin,” he said. He developed a short checklist to help determine who is at risk and could benefit from low-dose aspirin. It includes additional risk factors. He told the Medical Post that low-dose Aspirin may be warranted if a woman has one of the following risk factors: antiphospholipid antibody syndrome; chronic hypertension; prior preeclampsia; pre-pregnancy diabetes; pre-pregnancy BMI over 30 kg/m2; or assisted reproductive therapy. It could also help woman who have two or more of the following risk factors: prior placental abruption; multifetal pregnancy; chronic kidney disease; prior stillbirth; maternal age over 40 years; nulliparity; systemic lupus erythematosus; or prior intrauterine growth restriction. Dr. Venu Jain, an obstetrician and associate professor of medicine at the University of Alberta concurs there is insufficient uptake of low-dose Aspirin in high-risk women—especially those with diabetes, obesity or other factors. But even those with chronic hypertension often aren’t given aspirin. He was not involved in the study. There needs to be “consistent and systematic assessment of risk of preeclampsia in every woman who is pregnant,” he said. A large proportion of at-risk women will go on develop preeclampsia in the absence of low-dose ASA. He noted there is a tool offered by the U.K.’s The Fetal Medicine Foundation that can help doctors. Also, the upcoming SOGC guidelines (Dr. Jain is a coauthor) on hypertensive disorders of pregnancy has an increased emphasis on the use of low-dose aspirin. The study could be underestimating the use of low-dose Aspirin, according to Dr. Nicolette Caccia, an associate professor of medicine at the University of Toronto. She was not part of the study. The researchers used the BORN database “which is usually populated by hospital nurses, uses the patient antenatal record, which is often incomplete and does not capture ASA use in a robust form,” she said. Also, “The recommended dose of ASA 162 mg nightly is safe and the indications for use to reduce pregnancy complications is expanding,” she said.

Most at-risk women for preeclampsia not given recommended prevention

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