What are the recommendations for screening and managing preeclampsia in pregnant women?

Screening for Preeclampsia

All pregnant women should be screened for preeclampsia with blood pressure measurements at every prenatal visit throughout pregnancy, as this approach has substantial net benefit in reducing maternal and perinatal morbidity and mortality. 1

Universal Screening Recommendation

• Screen all pregnant women without known preeclampsia or hypertension using blood pressure measurements at each prenatal care visit. 1
• The USPSTF assigns this a Grade B recommendation with moderate certainty of substantial net benefit. 1
• Blood pressure screening is the primary and most established method for detecting preeclampsia, with well-documented accuracy. 1

Proper Blood Pressure Measurement Technique

To ensure accurate screening results, specific measurement protocols must be followed:

• Allow the patient to rest for 5 minutes before measurement. 1
• Position the patient sitting with legs uncrossed and back supported. 1
• Place the patient's arm at the level of the right atrium. 1
• Use a large blood pressure cuff if upper arm circumference is ≥33 cm. 1
• Avoid measuring blood pressure in the left lateral position, as this falsely lowers readings. 1
• Use sphygmomanometry as the recommended measurement method. 1

Confirmation of Abnormal Findings

• If blood pressure is elevated, confirm with repeated measurements before proceeding with further evaluation. 1
• Further diagnostic evaluation and clinical monitoring are indicated for patients with persistently elevated blood pressure on multiple measurements. 1

Risk Stratification

While all pregnant women require screening, certain populations have substantially elevated risk and warrant enhanced surveillance:

High-risk clinical conditions include: 1

• History of eclampsia or preeclampsia (particularly early-onset preeclampsia)
• Previous adverse pregnancy outcome
• Type 1 or 2 diabetes mellitus or gestational diabetes
• Chronic hypertension
• Renal disease
• Autoimmune diseases
• Multifetal gestation

Additional risk factors include: 1

• Nulliparity
• Obesity
• African American race
• Low socioeconomic status
• Advanced maternal age

Diagnostic Confirmation When Screening is Positive

When elevated blood pressure is confirmed, proteinuria assessment is essential:

• Screen initially with automated dipstick urinalysis. 1, 2
• If positive, quantify with urine protein/creatinine ratio (abnormal if ≥30 mg/mmol or 0.3 mg/mg). 1, 2
• Preeclampsia is defined as new-onset hypertension after 20 weeks gestation combined with either proteinuria or other signs of multiorgan involvement. 1

Prevention in High-Risk Women

For women with established strong clinical risk factors, initiate low-dose aspirin (81 mg daily) ideally before 16 weeks but definitely before 20 weeks of gestation. 1

This recommendation applies specifically to women with: 1

• Prior preeclampsia
• Chronic hypertension
• Pregestational diabetes mellitus
• Maternal BMI >30 kg/m²
• Antiphospholipid syndrome
• Receipt of assisted reproduction

Provide supplemental calcium (1.2-2.5 g/day) if dietary intake is likely <600 mg/day, in addition to aspirin. 1

Advanced First-Trimester Screening (Optional)

While not universally required, combined multimarker screening at 11-13+6 weeks can identify women who may benefit from aspirin prophylaxis:

• The Fetal Medicine Foundation triple test (maternal factors, mean arterial pressure, uterine artery pulsatility index, and serum placental growth factor) detects 90% of early preeclampsia and 75% of preterm preeclampsia with a 10% false-positive rate. 3
• This approach is superior to risk factor-based screening alone, which detects only 41% of preterm preeclampsia using NICE criteria and 5% using ACOG 2013 criteria. 3
• The number needed to screen to prevent one case of preterm preeclampsia is 250. 3
• However, the USPSTF found inadequate evidence to support routine use of risk prediction tools beyond clinical risk factors, as externally validated models lack adequate calibration and clinical implementation data. 4

Management of Diagnosed Preeclampsia

When preeclampsia is diagnosed, management strategies include: 1

• Close fetal and maternal monitoring
• Antihypertensive medications for severe hypertension
• Magnesium sulfate for seizure prophylaxis in severe cases

Critical Pitfalls to Avoid

• Do not rely solely on home blood pressure monitoring for screening; it is only a useful adjunct for chronic hypertension management. 1
• Do not use biomarkers like placental growth factor or sFlt-1/PlGF ratio for routine clinical diagnosis outside of research settings. 1
• Do not use low molecular weight heparin to prevent preeclampsia, even with prior early-onset disease. 1
• Ensure proper blood pressure measurement technique, as technical errors can lead to false results and inappropriate management decisions. 1

Postpartum Follow-up

• Review all women at 3 months postpartum to ensure blood pressure, urinalysis, and laboratory abnormalities have normalized. 1
• Women with gestational hypertension or preeclampsia face significant long-term cardiovascular risks and require annual medical review lifelong. 1
• Initial recommendation includes achieving prepregnancy weight by 12 months and limiting interpregnancy weight gain through healthy lifestyle modifications. 1