What are the guidelines for antenatal (prenatal) care?

Antenatal Care Guidelines

Antenatal care should follow a structured approach with early risk assessment before 20 weeks of gestation and appropriate monitoring frequency based on risk factors, with special attention to screening for pre-eclampsia. 1

Initial Risk Assessment (Before 20 Weeks)

• Identify pre-eclampsia risk factors at the first antenatal visit to determine appropriate care pathways 1:
  • First pregnancy (nulliparity) (RR 2.91) 1
  • Previous pre-eclampsia (RR 7.19) 1
  • ≥10 years since last pregnancy 1
  • Age ≥40 years (RR 1.68-1.96) 1, 2
  • Body mass index ≥35 1
  • Family history of pre-eclampsia (mother or sister) (RR 2.90) 1, 2
  • Booking diastolic blood pressure ≥80 mmHg 1
  • Proteinuria at booking (≥+ on more than one occasion or ≥300 mg/24h) 1
  • Multiple pregnancy (RR 2.93) 1, 2
  • Pre-existing medical conditions (diabetes, hypertension, renal disease) 1
  • Presence of antiphospholipid antibodies (RR 9.72) 1, 2

Referral Criteria for Specialist Care

• Offer women referral before 20 weeks for specialist input if they have 1:
  • Previous pre-eclampsia
  • Multiple pregnancy
  • Pre-existing hypertension (diastolic BP ≥90 mmHg)
  • Pre-existing renal disease or booking proteinuria
  • Pre-existing diabetes
  • Presence of antiphospholipid antibodies
  • Any two other risk factors from the assessment list 1

Timing of First Antenatal Visit

• The World Health Organization recommends first antenatal care visit within the first 12 weeks of gestation 3, 4
• Late initiation of antenatal care (after 12 weeks) is associated with poor pregnancy outcomes including perinatal death, stillbirth, and early neonatal death 5
• Common barriers to early initiation include:
  • Age ≥30 years 3
  • Unplanned pregnancy 3, 6
  • Misconceptions about correct timing 3, 6
  • No previous antenatal care experience 3, 6
  • Family size ≥4 6
  • Not being part of women's health development programs 6

Monitoring Schedule After 20 Weeks

• Two-tiered approach based on risk assessment 1:
  • Level 1 (Low Risk): Women with no risk factors - follow local protocols for low-risk multiparous women 1
  • Level 2 (Moderate Risk): Women with one risk factor (not requiring early referral) 1:
    • 24-32 weeks: Maximum 3-week intervals between assessments
    • 32 weeks to delivery: Maximum 2-week intervals between assessments

Content of Antenatal Assessments

• At every assessment, screen for signs and symptoms of pre-eclampsia 1:
  • New hypertension (diastolic BP ≥90 mmHg) 1
  • New proteinuria (≥+ on dipstick, protein:creatinine ratio ≥30 mg/mmol, or ≥300 mg/24h) 1, 2
  • Headache or visual disturbances 1
  • Epigastric pain or vomiting 1
  • Reduced fetal movements or small-for-gestational-age infant 1

Preventive Measures

• Prophylactic low-dose aspirin (100-150 mg daily) is recommended for women with 1:

  • Major risk factors: prior pre-eclampsia, chronic hypertension, pregestational diabetes, BMI >30, chronic kidney disease, antiphospholipid syndrome 1
  • Or ≥2 minor risk factors: advanced maternal age, family history of pre-eclampsia, short duration of sexual relationship before pregnancy, primiparity, primipaternity, connective tissue disorders 1
  • Start before 16 weeks' gestation and continue until 37 weeks 1

• Calcium supplementation (1200 mg daily) for women with low dietary calcium intake 1:

  • Can be initiated at first antenatal contact, even if earlier than 20 weeks 1
  • Can be taken with iron-folic acid supplements despite minor interaction concerns 1

Common Pitfalls in Antenatal Care

• Delayed initiation of antenatal care beyond 12 weeks reduces opportunities for early risk assessment and preventive interventions 3, 5
• Failure to identify and act on known risk factors at booking 1
• Inconsistent referral thresholds and assessment procedures 1
• Poor understanding of pre-eclampsia risk among pregnant women 1
• Starting calcium supplementation too late (optimal timing may be periconceptional) 1
• Lack of access to essential medications like magnesium sulfate in low-resource settings 1

Diagnostic Criteria for Pre-eclampsia

• Pre-eclampsia is defined as new hypertension (≥140/90 mmHg) after 20 weeks with 2:

  • Proteinuria (>0.3g/24h or albumin-creatinine ratio ≥30 mg/mmol) 2, OR
  • Maternal organ dysfunction (renal, liver, neurological complications) 2, OR
  • Uteroplacental dysfunction (fetal growth restriction, abnormal umbilical artery Doppler) 2

• Blood pressure should be confirmed on two separate occasions or at least 15 minutes apart in cases of severe hypertension (≥160/110 mmHg) 2