Caffeine during pregnancy: how much is safe?

The short answer: Limit to under 200 mg/day — about 1 cup (240 mL) of brewed coffee

Caffeine crosses the placenta and is metabolized slowly by the developing fetal liver. Most obstetric authorities (ACOG, RCOG, NICE, WHO) recommend keeping total daily caffeine under 200 mg throughout pregnancy. Some recent studies suggest a modest increase in miscarriage and low-birth-weight risk even at moderate doses, so many experts now advise "less is better."

Caffeine content of common sources

| Source | Typical caffeine (mg) | |---|---| | Brewed coffee (240 mL / 8 oz) | 95–165 | | Espresso shot (30 mL) | 60–80 | | Instant coffee (240 mL) | 60–85 | | Black tea (240 mL) | 40–70 | | Green tea (240 mL) | 25–50 | | Energy drink (250 mL) | 80–300 | | Cola (330 mL) | 30–45 | | Dark chocolate (28 g) | 12–25 | | Decaf coffee (240 mL) | 2–12 |

Why the 200 mg limit

• Caffeine half-life triples in late pregnancy (up to 15 hours vs 4–5 hours non-pregnant) because of reduced hepatic metabolism
• Fetal caffeine elimination relies on mother's liver — fetal CYP1A2 doesn't develop until infancy
• High caffeine (>300–500 mg/day) has been associated with:
• Increased miscarriage risk
• Low birth weight and IUGR
• Small increase in stillbirth risk in some studies

Practical guidance by trimester

• Trying to conceive and early pregnancy: most conservative period — aim for <100 mg/day, some women prefer zero
• Throughout pregnancy: <200 mg/day total from all sources
• Third trimester: half-life is longest; consider cutting back further if sleep is already poor
• Breastfeeding: caffeine transfers to milk; moderate amounts (200–300 mg/day) are generally considered safe but excessive maternal intake can cause infant irritability and poor sleep

What to watch for