Blurry vision is a common, temporary change in eyesight quality experienced by many women, particularly in the third trimester of pregnancy. These vision changes are often a side effect of the body’s physiological adaptations. While this symptom can cause anxiety as the delivery date nears, blurry vision is generally not a direct indication that labor is about to begin. It is important to distinguish between harmless, temporary changes and those that signal a more serious underlying condition.
Is Blurry Vision a Direct Sign of Labor?
Blurry vision is not a recognized physiological sign of impending or active labor. The body’s biological preparation for childbirth does not include specific changes to visual acuity. True signs that labor is starting are related to uterine activity and cervical changes. These signs include regular, painful contractions that increase in frequency and intensity, the rupture of the amniotic sac (water breaking), or the passing of the bloody show. Vision changes are simply not part of this progression toward delivery.
Benign Causes of Vision Changes During Pregnancy
The most common reasons for mild, intermittent blurry vision are temporary and hormone-related. Elevated levels of hormones like estrogen and progesterone cause the body to retain more fluid throughout the system. This fluid retention can extend to the eyes, causing the cornea (the clear front surface) to swell slightly. This corneal edema alters the cornea’s shape and thickness, changing how light is refracted onto the retina and resulting in subtle blurring. These changes are typically mild, do not require new corrective lenses, and resolve spontaneously after delivery. Hormonal shifts also frequently reduce tear production, leading to dry eyes. This lack of lubrication can cause irritation and intermittent blurriness that often improves with blinking.
Severe Vision Changes and Urgent Warning Signs
While most vision changes are harmless, sudden or persistent blurry vision, especially in the third trimester, can signal a serious complication. The primary concern is pre-eclampsia, characterized by new-onset high blood pressure and signs of damage to another organ system, typically after 20 weeks of gestation. Vision disturbances occur in about 25% of women with severe pre-eclampsia. These visual symptoms, which include blurred vision, light sensitivity, seeing spots, or flashing lights (scotomata), are often caused by vasospasm—the narrowing of retinal blood vessels due to severely elevated blood pressure.
This reduced blood flow can cause temporary or even permanent damage to the delicate structures of the eye. Preeclampsia can progress to eclampsia, which involves seizures and may cause more severe visual symptoms like double vision or temporary vision loss. Other symptoms that accompany vision changes and signal a need for urgent care include a persistent, severe headache that does not improve with rest or standard pain relievers, sudden and excessive swelling of the face and hands, and pain in the upper right side of the abdomen.
The combination of these symptoms indicates a systemic issue requiring immediate medical evaluation. Gestational diabetes, another complication, can also cause blurry vision due to fluctuations in blood sugar levels, which affect the shape of the eye’s lens.
Immediate Steps and Medical Consultation
For mild, intermittent blurriness not accompanied by other warning signs, several self-care steps can help manage discomfort. Ensuring adequate hydration and taking frequent breaks from screens can help reduce eye strain. Using preservative-free artificial tears can alleviate dryness and the associated blurriness, as hormonal changes often reduce natural tear production. It is recommended to use glasses instead of contact lenses during this time, as the subtle change in corneal shape can make contacts uncomfortable or ill-fitting. If the vision change is sudden, severe, or accompanied by any of the urgent symptoms—such as a relentless headache, flashes of light, dark spots, or upper right quadrant pain—immediate medical attention is required. Contact your healthcare provider or go directly to an emergency department to rule out or manage conditions like pre-eclampsia.