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Green Tea (240ml / 8oz)

Caffeine Half-Life Analysis

For: Pregnancy
28
mg Caffeine
10.5
Hour Half-Life
~N/A
Hours to Sleep-Safe
200
mg Daily Limit

trending_down Caffeine Decay Timeline

How 28mg caffeine clears from your system with a 10.5-hour half-life

Time Elapsed Caffeine Remaining % of Original Status
Now (consumption) 28.0 mg
100.0% 		Minimal
After 1 hour 26.2 mg
93.6% 		Minimal
After 2 hours 24.5 mg
87.6% 		Minimal
After 3 hours 23.0 mg
82.0% 		Minimal
After 4 hours 21.5 mg
76.8% 		Minimal
After 5 hours 20.1 mg
71.9% 		Minimal
After 6 hours 18.8 mg
67.3% 		Minimal
After 8 hours 16.5 mg
59.0% 		Minimal
After 10 hours 14.5 mg
51.7% 		Minimal
After 12 hours 12.7 mg
45.3% 		Minimal
After 16 hours 9.7 mg
34.8% 		Cleared
After 20 hours 7.5 mg
26.7% 		Cleared
After 24 hours 5.7 mg
20.5% 		Cleared

health_and_safety Health Insights for Pregnancy

⚠️ Important Health Consideration

During the third trimester, caffeine half-life can extend to 10-15 hours due to reduced CYP1A2 activity. Caffeine also crosses the placenta.

Daily Limit Calculation

  • • Recommended daily limit: 200mg of caffeine
  • • Caffeine per serving: 28mg
  • • Servings until limit: 7.1 servings

Limit caffeine to 200mg/day (about one 8oz cup of coffee). Consider switching to decaf in the afternoon.

Sleep Quality Impact

Caffeine blocks adenosine receptors in the brain, preventing the buildup of sleep pressure. Even when you don't feel "wired," residual caffeine can reduce deep sleep quality by up to 20%.

>100mg
May disrupt sleep
50-100mg
Reduced deep sleep
<50mg
Minimal impact

science How Caffeine Half-Life Works

Half-life is the time required for the body to eliminate 50% of a substance. For caffeine, this primarily occurs in the liver through the CYP1A2 enzyme system.

With a half-life of 10.5 hours for pregnancy, caffeine follows exponential decay:

  • After 10.5 hours: 50% remains (14.0mg)
  • After 21.0 hours: 25% remains (7.0mg)
  • After 31.5 hours: 12.5% remains (3.5mg)
  • After 42.0 hours: 6.25% remains (1.75mg)

The pregnancy category has a slower metabolism compared to healthy adults (5 hours baseline). During the third trimester, caffeine half-life can extend to 10-15 hours due to reduced CYP1A2 activity. Caffeine also crosses the placenta.

warning Important Health Notice

Limit caffeine to 200mg/day (about one 8oz cup of coffee). Consider switching to decaf in the afternoon.

Compare Other Drinks

Brewed Coffee (240ml / 8oz) 95mg Espresso (30ml / 1oz shot) 63mg Red Bull (250ml / 8.4oz) 80mg Monster Energy (473ml / 16oz) 160mg

Compare Conditions

Healthy Adult 5.0h Smokers 3.0h Birth Control Users 7.5h Liver Impairment 12.0h Elderly (65+) 6.5h Fast Metabolizers (Genetic) 3.5h

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About Green Tea (240ml / 8oz)

Brewed green tea

Note: Contains L-theanine which modulates caffeine's effects

help Frequently Asked Questions

How long does Green Tea (240ml / 8oz) caffeine last for pregnancy?

For pregnancy, the caffeine half-life is approximately 10.5 hours. This means that 28mg of caffeine from Green Tea (240ml / 8oz) will take about 10.5 hours to reduce to 14mg, and 21.0 hours to drop to 7mg. Full clearance (below 10mg) takes approximately 15.6 hours.

When should I stop drinking Green Tea (240ml / 8oz) to sleep well?

If you plan to sleep at 10 PM, you should consume your last Green Tea (240ml / 8oz) by any time - caffeine level is low. This allows approximately sufficient hours for caffeine levels to drop below the sleep disruption threshold of 100mg.

How does being in the 'Pregnancy' category affect caffeine metabolism?

During the third trimester, caffeine half-life can extend to 10-15 hours due to reduced CYP1A2 activity. Caffeine also crosses the placenta. Limit caffeine to 200mg/day (about one 8oz cup of coffee). Consider switching to decaf in the afternoon.