Sinusitis: This is a common condition in pregnancy due to increased blood volume and congestion. The facial pressure behind the eye could be indicative of maxillary or ethmoid sinusitis, which are the sinuses closest to the eyes.

Tension Headache: Hormonal changes during pregnancy can lead to tension headaches, which may cause facial pressure and pain behind the eyes.
Migraine: Migraines are common in women of childbearing age and can be exacerbated by pregnancy. They often present with unilateral pain and can cause pressure sensations behind the eyes.
Allergies: Seasonal or environmental allergies can cause sinus congestion, leading to facial pressure and discomfort behind the eyes.

Preeclampsia: Although less common, preeclampsia can cause severe headaches and visual disturbances, including pressure behind the eyes. It's a critical condition that requires immediate medical attention.
Stroke or Transient Ischemic Attack (TIA): While rare, stroke or TIA can present with sudden onset of headache and facial pain. Given the potential for severe outcomes, these conditions must be considered.
Idiopathic Intracranial Hypertension (IIH): Also known as pseudotumor cerebri, IIH can cause increased pressure around the brain, leading to headaches and vision changes, including pressure behind the eyes.

Trigeminal Neuralgia: A condition that affects the trigeminal nerve, causing intense pain in the face, which could be perceived as pressure behind the eye.
Temporal Arteritis: An inflammation of the blood vessels in the head, which can cause severe headaches and facial pain, but is less common in younger individuals, including those of typical childbearing age.
Cavernous Sinus Thrombosis: A rare but serious condition involving a blood clot in the cavernous sinus, which can cause facial pain, headache, and eye symptoms due to its location near the base of the brain.