USPSTF: Aspirin Advised When Preeclampsia Risk Is High

Jenni Laidman

September 09, 2014

Healthy pregnant women at high risk for preeclampsia should take low-dose aspirin daily after 12 weeks of gestation, the US Preventive Services Task Force recommends in new guidelines published online September 9 in the Annals of Internal Medicine.

This new recommendation takes a stronger stance than guidelines adopted by the American College of Obstetrics and Gynecology (ACOG) a year and a half ago. At that time, ACOG made a qualified recommendation for low-dose aspirin among women at high risk for preeclampsia, noting moderate evidence for a small reduction in risk. In the latest recommendations, the Preventive Services Task Force reports that low-dose aspirin in high-risk women reduced preeclampsia 24% (pooled relative risk [RR], 0.76; 95% confidence interval [CI], 0.62 - 0.95).

"In the year and a half since the ACOG recommendations came out, there's new evidence that moves the needle toward a stronger recommendation," Virginia R. Lupo, MD, maternal-fetal medicine specialist and chair of obstetric-gynecology at the Hennepin County Medical Center, Minneapolis, Minnesota, told Medscape Medical News. Dr. Lupo, a spokesman for the ACOG, was not involved in the Preventive Services Task Force report or the ACOG recommendations.

The Preventive Services Task Force also recommends that any woman who may become pregnant take a daily supplement containing 0.4 to 0.8 mg folic acid.

The task force says women are at high risk when they have 1 or more of the following factors: a history of preeclampsia, especially when accompanied by adverse outcome; a multifetal pregnancy; chronic hypertension; diabetes, either type 1 or 2; renal disease; or autoimmune disease such as systemic lupus erythematous or antiphospholipid syndrome.

For women at moderate risk for preeclampsia, the task force recommends that low-dose aspirin be considered and the risk factors discussed with the patient. A woman is considered "moderate risk" if she has several of the following risk factors: nulliparity, obesity, a mother or sister with preeclampsia, personal history factors such as previous adverse pregnancy outcome, low birthweight, small for gestational age; and a greater than 10-year pregnancy interval; if she is black; if she is of low socioeconomic status; or if she is 34 years old or older.

Despite the now recognized benefits of low-dose aspirin for certain pregnant women, Dr. Lupo says it will still take years for the advice to be adopted. "The literature shows it can take even decades before even high-quality recommendations are implemented. I'm certain the entire community of physicians is not on board yet. Changing how we treat people is like moving a huge air craft carrier and turning it around. It takes awhile."

Low-dose aspirin likely has other benefits in pregnancy beyond reducing preeclampsia risk. In a meta-analysis of several randomized trials, the task force found evidence of a 14% risk reduction for preterm birth (RR 0.86; 95% CI, 0.76 - 0.98) in women at increased preeclampsia risk who received low-dose aspirin. There was also a 20% reduction in risk for intrauterine growth restriction (RR, 0.80; 95% CI, 0.65 - 0.99). Low-dose aspirin increased mean birth weights by a pooled weight mean difference of 130.0 g (95% CI, 36.2 - 222.3 g). However, an analysis examining the effect on perinatal mortality did not reach statistical significance.

Low-dose aspirin did not increase the risk for placental abruption, postpartum hemorrhage, or fetal harm, such as intracranial bleeding and birth defects, the task force analysis showed.

The number needed to treat to prevent 1 preeclampsia diagnosis was 42 (95% CI, 26 - 200). To prevent a single case of intrauterine growth restriction, 71 women would need to be treated (95% CI, 41 - 1429), and to prevent a preterm birth, 65 women need to be treated (95% CI, 38 - 455).

Preeclampsia, a leading cause of health complications for expectant mothers and their babies, is marked by a rise in blood pressure of more than 140/90 mm Hg and excess protein in the urine (0.3 g or more within 24 hours) after 20 weeks of pregnancy. It affects between 2% and 8% of all pregnancies worldwide and accounts for 15% of preterm births in the United States.

In absence of proteinuria, preeclampsia is hypertension with any of the following: cerebral or visual disturbances, impaired liver function, pulmonary edema, renal insufficiency, or thrombocytopenia.

Dr. Lupo has disclosed no relevant financial relationships.

Ann Intern Med. Published online September 9, 2014. Full text

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