Definitions of the levels of evidence (I, II-1, II-2, II-3, and III) and grades of recommendations (A-E and I) are provided at the end of the "Major Recommendations" field.
Prediction, Prevention, and Prognosis of Preeclampsia
Predicting Preeclampsia
- At booking for antenatal care, women with markers of increased risk for preeclampsia should be offered obstetric consultation. (II-2B)
- Women at increased risk of preeclampsia should be considered for risk stratification involving a multivariable clinical and laboratory approach. (II-2B)
Preventing Preeclampsia and its Complications in Women at Low Risk
- Calcium supplementation (of at least 1gram/day (g/d), orally) is recommended for women with low dietary intake of calcium (< 600 milligram (mg)/d). (I-A)
- The following are recommended for other established beneficial effects in pregnancy: abstention from alcohol for prevention of fetal alcohol effects (II-2E), exercise for maintenance of fitness (I-A), periconceptual use of a folate-containing multivitamin for prevention of neural tube defects (I-A), and smoking cessation for prevention of low birthweight and preterm birth. (I-E)
- The following may be useful: periconceptual use of a folate-containing multivitamin, (I-B) or exercise. (II-2B)
- The following are not recommended for preeclampsia prevention, but may be useful for prevention of other pregnancy complications: prostaglandin precursors (I- C), or supplementation with magnesium (I-C), or zinc (I-C).
- The following are not recommended: dietary salt restriction during pregnancy (I-D), calorie restriction during pregnancy for overweight women (I-D), low-dose aspirin (I-E), vitamins C and E (based on current evidence) (I-E), or thiazide diuretics (I-E).
- There is insufficient evidence to make a recommendation about the following: a heart-healthy diet, (II-2 I) workload or stress reduction, (II-2 I) supplementation with iron with/without folate, (I-I) or pyridoxine. (I-I).
Preventing Preeclampsia and its Complications in Women at Increased Risk
- Low-dose aspirin (I-A) and calcium supplementation (of at least 1 g/d) are recommended for women with low calcium intake (I-A), and the following are recommended for other established beneficial effects in pregnancy (as discussed for women at low risk of preeclampsia): abstention from alcohol (II-2E), periconceptual use of a folate-containing multivitamin (I-A), and smoking cessation (I-E).
- Low-dose aspirin (75 to 100 mg/d) (III-B) should be administered at bedtime (I-B), starting pre-pregnancy or from diagnosis of pregnancy but before 16 weeks' gestation (III-B), and continuing until delivery (I-A).
- The following may be useful: avoidance of inter-pregnancy weight gain (II-2E), increased rest at home in the third trimester (I-C), and reduction of workload or stress (III-C).
- The following are not recommended for preeclampsia prevention but may be useful for prevention of other pregnancy complications: prostaglandin precursors (I-C) and magnesium supplementation (I-C).
- The following are not recommended: calorie restriction in overweight women during pregnancy, (I-D) weight maintenance in obese women during pregnancy (III-D), antihypertensive therapy specifically to prevent preeclampsia (I-D), vitamins C and E (I-E).
- There is insufficient evidence to make a recommendation about the usefulness of the following: the heart-healthy diet (III-I); exercise (I-I); heparin, even among women with thrombophilia and/or previous preeclampsia (based on current evidence) (II-2 I); selenium (I-I); garlic (I-I); zinc, (III-I), pyridoxine, (III-I) iron (with or without folate), (III-I) or multivitamins with/without micronutrients. (III-I)
Prognosis (Maternal and Fetal) in Preeclampsia
- Serial surveillance of maternal well-being is recommended, both antenatally and post partum (II-3B).
- The frequency of maternal surveillance should be at least once per week antenatally, and at least once in the first three days post partum (III-C).
- Serial surveillance of fetal well-being is recommended (II-2B).
- Antenatal fetal surveillance should include umbilical artery Doppler velocimetry (I-A).
- Women who develop gestational hypertension with neither proteinuria nor adverse conditions before 34 weeks should be followed closely for maternal and perinatal complications (II-2B).
Definitions:
Quality of Evidence Assessment*
I: Evidence obtained from at least one properly randomized controlled trial
II-1: Evidence from well-designed controlled trials without randomization
II-2: Evidence from well-designed cohort (prospective or retrospective) or case-control studies, preferably from more than one centre or research group
II-3: Evidence obtained from comparisons between times or places with or without the intervention. Dramatic results in uncontrolled experiments (such as the results of treatment with penicillin in the 1940s) could also be included in this category
III: Opinions of respected authorities, based on clinical experience, descriptive studies, or reports of expert committees
Classification of Recommendations**
A. There is good evidence to recommend the clinical preventive action
B. There is fair evidence to recommend the clinical preventive action
C. The existing evidence is conflicting and does not allow to make a recommendation for or against use of the clinical preventive action; however, other factors may influence decision-making
D. There is fair evidence to recommend against the clinical preventive action
E. There is good evidence to recommend against the clinical preventive action
I. There is insufficient evidence (in quantity or quality) to make a recommendation; however, other factors may influence decision-making
*The quality of evidence reported in these guidelines has been adapted from the Evaluation of Evidence criteria described in the Canadian Task Force on the Preventive Health Care.
**Recommendations included in these guidelines have been adapted from the Classification of Recommendations criteria described in the Canadian Task Force on the Preventive Health Care.
