What Causes Headaches During Pregnancy (Third Trimester)?

Headaches in the second or third trimester could be due to preeclampsia, a serious pregnancy complication that causes high blood pressure (hypertension) and organ injury. Other causes may include stress, sinus congestion, eye strain, fatigue/lack of sleep, allergies, dehydration, hunger, poor diet, excess weight, high blood sugar (hyperglycemia)/diabetes, depression, caffeine withdrawal, and more.
Headaches in the second or third trimester could be due to preeclampsia, a serious pregnancy complication that causes high blood pressure (hypertension) and organ injury. Other causes may include stress, sinus congestion, eye strain, fatigue/lack of sleep, allergies, dehydration, hunger, poor diet, excess weight, high blood sugar (hyperglycemia)/diabetes, depression, caffeine withdrawal, and more.     

Headaches during pregnancy are common, and they often occur in the first trimester due to increased hormones and increased blood volume and circulation. Headaches tend to fade and may even disappear during the second and third trimester of pregnancy, though some women may still experience them occasionally. 

If you experience headaches in the second or third trimester of pregnancy, this could also be a sign of preeclampsia, which is a serious complication of pregnancy in which high blood pressure (hypertension) and evidence of organ injury develops in pregnant women after 20 weeks of pregnancy. 

See your doctor right away if you have a severe headache that does not go away, sudden swelling, changes in vision, or unexplained weight gain, which may indicate preeclampsia.

Other causes of headaches during the third trimester of pregnancy may include:

How Do You Treat Headaches During Pregnancy (Third Trimester)?

Headache pain during the third trimester of pregnancy may be relieved by home remedies such as: 

  • Keeping track of headache triggers in a diary 
  • Using a warm or cool compress applied to the forehead or base of the skull
  • Taking a cool or warm shower or bath, or splashing cool water on your face
  • Eating small meals frequently to prevent low blood sugar
  • Staying hydrated
  • Getting adequate sleep
  • Regular exercise 
  • Avoiding common migraine triggers such as:
    • Loud noises
    • Tobacco smoke
    • Glaring or flickering lights
    • Excessive heat or cold
    • Strong odors
    • Foods and food additives
      • Aged cheese and cultured dairy products such as sour cream and buttermilk
      • Some fresh fruits including citrus fruits, bananas, avocados, and papayas
      • Smoked fish
      • Chocolate and carob
      • Certain beans and nuts
      • Fermented or pickled foods such as sauerkraut or soy sauce
      • Monosodium glutamate (MSG)
      • Nitrites and nitrates, such as found in processed meats such as hot dogs, salami, and bacon
      • Artificial sweeteners
  • Relaxation techniques
    • Meditation
    • Yoga
    • Self-hypnosis
    • Biofeedback
  • Getting a massage
  • Acupuncture
  • Over-the-counter (OTC) medicines
    • Acetaminophen (Tylenol) is generally considered safe for use during pregnancy when used as directed on the package label, but other OTC headache medicines such as aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) including ibuprofen (Advil, Motrin) and naproxen (Aleve), and most prescription migraine headache medications are not recommended for use by pregnant women
    • Talk to your doctor before taking any OTC headache medication or supplement during pregnancy
References
https://www.babycenter.com/pregnancy/your-body/headaches-during-pregnancy_2035

https://www.cdc.gov/pregnancy/documents/Diabetes_and_Pregnancy508.pdf