Below is a **complete, concise-but-exhaustive, exam-ready medical reference** on **Pregnancy-Induced Hypertension (PIH)**—also called **gestational hypertension**.
Covers: **definition, pathophysiology, etiologies, risk factors, clinical features, investigations, differential diagnosis, complications (maternal & fetal), management (stepwise), drugs with dosing + MOA + AEs + contraindications + monitoring**, delivery timing, prevention, counseling.

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# ⭐ **PREGNANCY-INDUCED HYPERTENSION (PIH) — COMPLETE DETAILS**




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# **1️⃣ Definition**

**PIH = Gestational Hypertension**

* **BP ≥140/90 mmHg** after **20 weeks** of pregnancy
* **No proteinuria**
* **No features of end-organ dysfunction**
* BP becomes normal within **12 weeks postpartum**

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# **2️⃣ Epidemiology**

* Occurs in **6–10%** of pregnancies
* More common in **primigravida**, **multiple gestation**, **teenage pregnancy**, **advanced maternal age**

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# **3️⃣ Etiology & Risk Factors**

### **Major Risk Factors**

* Primigravida
* Family history of PIH/Preeclampsia
* Personal history of PIH
* Multiple pregnancy
* Molar pregnancy
* Diabetes, Obesity, Chronic hypertension
* Autoimmune disease
* Renal disease
* Thrombophilias
* Advanced maternal age (>35 years)

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# **4️⃣ Pathophysiology (Simplified & Complete)**



### **Normal Pregnancy**

* Trophoblast invades → spiral arteries remodel → become wide, low-resistance → good placental perfusion.

### **PIH / Preeclampsia Spectrum**

1. **Defective trophoblastic invasion** → incomplete spiral artery remodeling
2. **Placental ischemia** → oxidative stress
3. **Release of antiangiogenic factors** (sFlt-1, endoglin) and inflammatory mediators
4. **Maternal endothelial dysfunction** →

* ↑ vascular resistance
* ↑ capillary permeability
* Hypercoagulability

🔹 **PIH = mild endotheliopathy without proteinuria or organ dysfunction**
🔹 **Preeclampsia = PIH + proteinuria or organ dysfunction**

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# **5️⃣ Diagnostic Criteria**

### **BP Measurement**

* Two readings ≥140/90 mmHg
* At least 4 hours apart
* After 20 weeks gestation
* No proteinuria
* No systemic symptoms

### **Proteinuria must be absent**

* Dipstick <1+
* Spot urine protein/creatinine ratio <0.3
* 24-hr urinary protein <300 mg

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# **6️⃣ Clinical Features**

### **Usually Asymptomatic**

Detected on routine antenatal screening.

### **If symptoms appear**

* Headache
* Mild pedal edema
* Dizziness
* Visual disturbances (suggest severe disease progression)
* Epigastric pain (danger sign)

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# **7️⃣ Investigations (Complete Panel)**

### **Basic**

* BP monitoring
* Urinalysis (protein)
* CBC
* LFTs (AST/ALT)
* Renal function test (creatinine, uric acid)

### **For progression to Preeclampsia**

* Urine PCR
* Peripheral smear (hemolysis)
* Coagulation profile
* LDH
* Fundus examination

### **Fetal Evaluation**

* Ultrasound for growth
* AFI
* Doppler velocimetry
* NST / BPP

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# **8️⃣ Differential Diagnosis**

* **Chronic hypertension**
* **White coat hypertension**
* **Preeclampsia**
* **Transient hypertension of pregnancy**
* **Renal disease**
* **Thyroid disorders**
* **Drug-induced hypertension**

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# **9️⃣ Maternal Complications**

### **If PIH progresses → Preeclampsia/Eclampsia**

* Severe hypertension
* HELLP syndrome
* DIC
* Acute renal failure
* Pulmonary edema
* Placental abruption
* Eclampsia
* Stroke / Intracranial hemorrhage

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# **🔟 Fetal Complications**

* IUGR
* Oligohydramnios
* Preterm birth
* Fetal hypoxia
* Placental insufficiency
* Stillbirth

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# **1️⃣1️⃣ Management (Complete Stepwise Protocol)**



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## **A. General Measures**

* Rest, preferably left lateral
* Reduce physical stress
* Salt restriction **NOT** recommended severely, only normal diet
* Daily fetal movement count
* Regular BP monitoring
* Weekly ANC visits

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## **B. Threshold for Treatment**

* **Treat if BP ≥150/100 mmHg**
* For **140–149/90–99 → Monitor only**, no medication unless comorbidity

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## **C. First-Line Antihypertensive Drugs in Pregnancy**

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# **🔹1. Labetalol (Drug of Choice)**

**MOA:** α-1 & β-blocker → ↓ SVR & BP
**Dose:**

* Oral: 100–200 mg twice daily → up to 2,400 mg/day
* IV (for severe): 20 mg bolus → 40 mg → 80 mg q10min (max 300 mg)
**PK:** Hepatic metabolism
**Common AEs:** Fatigue, dizziness
**Serious AEs:** Bradycardia, hypotension
**Contraindications:** Asthma, heart block
**Monitoring:** BP, HR
**Counselling:** Avoid abrupt stopping

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# **🔹2. Nifedipine (Long-acting)**

**MOA:** Calcium channel blocker → vasodilation
**Dose:** 30–60 mg sustained-release OD
**PK:** Hepatic
**Common AEs:** Headache, flushing
**Serious AEs:** Hypotension
**Contraindications:** Aortic stenosis
**Interactions:** Magnesium sulfate ↑ hypotension risk
**Monitoring:** BP
**Counselling:** Do not chew CR tablets

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# **🔹3. Methyldopa (Safe in pregnancy)**

**MOA:** Central α2 agonist
**Dose:** 250–500 mg 2–3 times/day
**PK:** Renal
**Common AEs:** Sedation, depression, dry mouth
**Serious AEs:** Liver dysfunction, hemolytic anemia
**Monitoring:** LFTs
**Counselling:** May cause drowsiness

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# ❌ **Drugs Contraindicated**

* ACE inhibitors
* ARBs
* Atenolol
* Diuretics (except pulmonary edema)

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# **1️⃣2️⃣ Management of Severe PIH**

* BP ≥160/110 mmHg
* Admit
* IV labetalol / oral nifedipine
* Evaluate for preeclampsia
* Magnesium sulfate if criteria for severe features

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# **1️⃣3️⃣ Magnesium Sulfate (for progression to severe/eclampsia)**

**MOA:** CNS depressant → prevents seizures by NMDA blockade
**Dose (Pritchard):**

* 4 g IV loading + 10 g IM (5 g each buttock)
* 5 g IM q4h
**Monitoring:**
* Respiratory rate
* Urine output (>30 ml/hr)
* Patellar reflex
**Toxicity:** Respiratory depression → treat with **10% calcium gluconate 10 ml IV**

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# **1️⃣4️⃣ Delivery Timing**

| Condition | Timing |
| ------------------------------------------------ | ------------------------- |
| **PIH (controlled)** | **37 weeks** |
| **Severe PIH** | 34 weeks (after steroids) |
| **Uncontrolled BP, fetal compromise, abruption** | Immediate delivery |

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# **1️⃣5️⃣ Intrapartum Care**

* Continuous fetal monitoring
* Keep BP <160/110
* Avoid fluid overload
* Anesthesia: regional preferred unless contraindicated

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# **1️⃣6️⃣ Postpartum Care**

* Continue antihypertensives
* Monitor BP for **12 weeks**
* If persistent → chronic hypertension

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# **1️⃣7️⃣ Prevention of PIH**

* Low-dose **Aspirin 75–150 mg at bedtime** from **12–16 weeks** in high-risk women
* Calcium supplementation (1–1.5 g/day) in low-calcium diets
* Weight control
* Control comorbidities

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# **1️⃣8️⃣ Patient Counseling Points**

* Regular BP monitoring
* Danger signs: headache, visual symptoms, epigastric pain
* Adherence to medications
* Fetal kick count
* Importance of follow-up
* No self-discontinuation of drugs

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✅ **Flowchart of PIH diagnosis**
✅ **Flowchart of management**
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