Antenatal Care & Complications

Antenatal Care & Complications

Antenatal Monitoring and Screening Schedules

Antenatal care (ANC) is the cornerstone of maternal and fetal health. According to international standards and Dubai Health Authority (DHA) protocols, a normal, low-risk pregnancy schedule involves clinical evaluations at regular intervals:

• Up to 28 weeks gestation: Monthly visits (every 4 weeks).
• 28 to 36 weeks gestation: Biweekly visits (every 2 weeks).
• From 36 weeks to delivery: Weekly visits.

At each visit, the nurse performs key assessments: maternal weight, blood pressure, urinalysis (for protein and glucose), and measurement of symphysis-fundal height (SFH) starting from 20 weeks. Between 20 and 36 weeks, the fundal height in centimeters should correspond closely to the gestational age in weeks (± 2 cm). A discrepancy requires ultrasound evaluation to rule out intrauterine growth restriction (IUGR) or polyhydramnios.

Prenatal Screening Protocols

Nurses must guide patients through the timeline of prenatal screening and diagnostic tests:

1. First Trimester Screening (11 to 13 weeks + 6 days): Combines maternal blood test (Pregnancy-Associated Plasma Protein-A [PAPP-A] and free beta-human chorionic gonadotropin [β-hCG]) with a fetal ultrasound measuring nuchal translucency (NT). An increased NT thickness suggests chromosomal abnormalities, particularly Down syndrome (Trisomy 21), or congenital heart defects.
2. Second Trimester Screening (15 to 20 weeks): The Quad screen measures maternal serum alpha-fetoprotein (MSAFP), hCG, estriol, and inhibin-A. Elevated MSAFP levels indicate neural tube defects (e.g., spina bifida, anencephaly), whereas low MSAFP levels are associated with Trisomy 21 and 18.
3. Anatomy Scan (18 to 22 weeks): A detailed fetal ultrasound screening for structural abnormalities, amniotic fluid volume assessment, and placental localization.
4. Group B Streptococcus (GBS) Screening (35 to 37 weeks): Vaginal and rectal swabs are collected. Positive maternal carriers require intrapartum prophylactic antibiotics (penicillin G is the first choice) to prevent neonatal sepsis.

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Gestational Diabetes Mellitus (GDM)

Gestational Diabetes Mellitus is characterized by glucose intolerance with onset during pregnancy. It is driven by placental hormones—specifically human placental lactogen (hPL), progesterone, growth hormone, and corticotropin-releasing hormone—which induce maternal insulin resistance to ensure a continuous supply of glucose to the fetus.

Screening and Diagnosis

Universal screening is performed between 24 and 28 weeks gestation.

• The One-Step Strategy (Preferred by WHO and DHA): Performs a 2-hour, 75g Oral Glucose Tolerance Test (OGTT) after an 8-hour overnight fast. Diagnosis is established if any of the following values are met or exceeded:
  • Fasting: 92 mg/dL (5.1 mmol/L)
  • 1 Hour: 180 mg/dL (10.0 mmol/L)
  • 2 Hours: 153 mg/dL (8.5 mmol/L)
• The Two-Step Strategy: A non-fasting 50g Glucose Challenge Test (GCT). If blood glucose at 1 hour is ≥ 130–140 mg/dL (7.2–7.8 mmol/L), a diagnostic 3-hour, 100g OGTT is performed.

Clinical Management

1. Nutritional Therapy: The primary intervention. Patients are advised to distribute carbohydrates across three meals and three snacks, avoiding simple sugars.
2. Blood Glucose Targets:

• Fasting: < 95 mg/dL (5.3 mmol/L)
• 1-hour postprandial: < 140 mg/dL (7.8 mmol/L)
• 2-hour postprandial: < 120 mg/dL (6.7 mmol/L)

1. Pharmacological Therapy: Initiated if diet and exercise fail to maintain glycemic control within 1–2 weeks. Insulin is the gold standard because it does not cross the placenta. Oral hypoglycemics (metformin, glyburide) are considered secondary options in some guidelines but require caution.
2. Neonatal Risks: Hyperinsulinemia in the fetus acts as a growth hormone, causing macrosomia (birth weight > 4,000g), which increases the risk of shoulder dystocia, clavicle fractures, and birth canal lacerations. Post-delivery, the infant is at high risk for neonatal hypoglycemia due to hyperinsulinemia responding to the sudden cessation of maternal glucose. Elevated fetal insulin also delays surfactant production, increasing the risk of respiratory distress syndrome (RDS).

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Hypertensive Disorders of Pregnancy

Hypertensive disorders are leading causes of maternal morbidity and mortality. Preeclampsia is a multisystem syndrome characterized by widespread endothelial dysfunction and vasospasm.

Classification

• Gestational Hypertension: BP ≥ 140/90 mmHg on two occasions at least 4 hours apart after 20 weeks gestation, without proteinuria or end-organ dysfunction.
• Preeclampsia: BP ≥ 140/90 mmHg after 20 weeks gestation with proteinuria (≥ 300 mg per 24-hour urine collection, or protein-to-creatinine ratio ≥ 0.3, or dipstick reading of 1+).
• Preeclampsia with Severe Features: Diagnosed when any of the following are present:
  • BP ≥ 160/110 mmHg on two occasions at least 4 hours apart while on bed rest.
  • Thrombocytopenia (platelet count < 100,000/μL).
  • Impaired liver function (liver enzymes transaminases elevated to twice normal; severe persistent right upper quadrant or epigastric pain).
  • Progressive renal insufficiency (serum creatinine > 1.1 mg/dL or doubling of baseline).
  • Pulmonary edema.
  • New-onset cerebral or visual disturbances (e.g., severe headache, scotomata, blurred vision).
• HELLP Syndrome: A severe variant of preeclampsia characterized by Hemolysis (microangiopathic hemolytic anemia with schistocytes on peripheral smear), Elevated Liver enzymes, and Low Platelets.

Nursing and Collaborative Management

Definitive treatment for preeclampsia is delivery of the fetus and placenta. However, management is aimed at preventing maternal seizures (eclampsia) and stabilizing blood pressure:

1. Seizure Prophylaxis: Magnesium Sulfate (MgSO4) is administered intravenously as a seizure prevention agent.
   • Loading dose: 4 to 6 grams administered over 15 to 20 minutes.
   • Maintenance dose: 1 to 2 grams per hour continuous infusion.
   • Therapeutic serum levels: 4 to 7 mEq/L (2.0 to 3.5 mmol/L).
2. Magnesium Toxicity Monitoring: The nurse must assess the patient hourly for signs of magnesium toxicity:
   • Deep Tendon Reflexes (DTRs): Patellar reflexes must be present. Loss of DTRs is the earliest sign of toxicity.
   • Respiratory Rate: Must remain ≥ 12 breaths/minute. Bradypnea indicates respiratory depression.
   • Urine Output: Must remain ≥ 30 mL/hour. Magnesium is excreted solely by the kidneys; oliguria causes rapid accumulation.
   • Level of Consciousness: Drowsiness, slurred speech, or confusion.
   • Antidote: Calcium Gluconate (10 mL of 10% solution administered IV push over 3 minutes) must be kept at the bedside.
3. Antihypertensive Administration: Used to prevent maternal stroke when BP exceeds 160/110 mmHg. First-line agents include Labetalol (contraindicated in asthma), Hydralazine, and oral Nifedipine.

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Clinical Traps & Exam Tips

• GDM Diagnosis Trap: On the exam, do not confuse the screening (50g GCT) with the diagnostic test (75g or 100g OGTT). A single abnormal value on a 75g OGTT is sufficient to diagnose GDM under current DHA guidelines.
• Magnesium Sulfate Misconception: Magnesium sulfate is not administered to lower blood pressure, though it has mild vasodilatory properties. Its sole therapeutic purpose is to prevent eclamptic seizures by raising the seizure threshold. Antihypertensives (like Labetalol or Hydralazine) are used to manage severe hypertension.
• Urinary Output Assessment: If a patient receiving Magnesium Sulfate has a urine output of 20 mL/hour, the nurse's priority action is to stop the magnesium infusion immediately, perform a focused physical assessment (respirations and DTRs), and notify the physician.