Why Pregnancy Rhinitis Happens
Pregnancy rhinitis occurs due to nasal vascular pooling caused by vasodilation and increased blood volume during pregnancy 1.
Pathophysiological Mechanism
The underlying cause is primarily vascular and hemodynamic changes rather than a single hormonal trigger:
- Increased circulating blood volume leads to engorgement of nasal blood vessels
- Vasodilation of nasal vasculature creates pooling of blood in the nasal mucosa
- These changes result in mucosal swelling and increased nasal secretions 1
Hormonal Influences (Assumed but Not Proven)
While hormonal changes are widely assumed to contribute, there is actually no convincing evidence that hormones directly cause pregnancy rhinitis 1. The guideline explicitly states this important caveat. However, research studies have explored potential hormonal associations:
- Elevated estrogen, progesterone, placental growth hormone, and insulin-like growth factor-1 levels occur during pregnancy 2, 3
- Women with pregnancy rhinitis showed non-significantly higher oestrogen and IGF-1 levels in one study 3
- These hormones may influence nasal mucosal secretions and vascular tone 4
Clinical Characteristics
Pregnancy rhinitis is 6 times more common in pregnant than non-pregnant women 1. The condition:
- Starts after the second month of pregnancy (typically not in the last 6 weeks/after 34 weeks gestation) 1
- Presents with significant nasal congestion as the predominant symptom 1
- Usually disappears within 2 weeks after delivery 1
- Occurs without infectious, allergic, or medication-related causes 1
Important Clinical Pitfall
Do not confuse pregnancy rhinitis with other causes of nasal symptoms during pregnancy. The most common causes of rhinitis during pregnancy are actually:
- Allergic rhinitis (worsens in approximately 1/3 of pregnant patients)
- Sinusitis
- Rhinitis medicamentosa
- Vasomotor rhinitis of pregnancy 1
The same vascular pooling mechanism that causes pregnancy rhinitis also accounts for worsening of pre-existing allergic rhinitis and increased sinusitis during pregnancy 1.
Risk Factors
Research has identified:
- Smoking 5
- Sensitization to house dust mites 5
- Carrying a female fetus (significantly associated in some studies) 3, 6
Clinical Significance
When pregnancy rhinitis causes snoring, it may be a factor in the development of pre-eclampsia 1. The condition affects quality of life in approximately 54% of affected women and may impact fetal oxygenation 7, 6.