Matcha in pregnancy.

The limit, and where it comes from

EFSA, the European food safety authority, concluded in 2015 that habitual caffeine intakes up to 200 mg a day in pregnancy do not raise safety concerns for the fetus. Australia's Pregnancy, Birth and Baby service gives the same 200 mg maximum, and FSANZ refers to the same body of evidence.

Caffeine per serve

Matcha at 32 mg per gram and teas per 100 ml from Japan's Standard Tables of Food Composition. Coffee from the Australian Institute of Sport. Real figures vary with serve size and brewing.

Pregnancy, Birth and Baby describes 200 mg in different ways on different pages, from about four cups of medium strength tea to one cup of tea at 30 mg. Both are fair: brewed tea varies a lot with leaf and strength. Matcha is different because you drink the whole leaf, so count it by grams.

Why caffeine lingers in pregnancy

Pregnancy hormones slow the liver enzyme that clears caffeine. FSANZ's caffeine safety assessment for proposal P1056 notes the half life rises to about 10 hours by 17 weeks and up to about 18 hours by the end of pregnancy. EFSA gives up to about 16 hours. Caffeine also crosses the placenta, and the fetus cannot break it down.

In practice: a matcha at 3 pm can still be with you at bedtime. The planner below is set to the pregnancy limit and a slow half life so you can see it.

What the evidence says, graded

Two lines in that chart deserve a plain word. There is no evidence that caffeine from matcha behaves differently in pregnancy from caffeine in coffee; count it the same. And theanine supplements have not been studied enough in pregnancy to call safe, so tea is not a reason to take them.

Gentler options

1. Use less matcha. 1 g in a latte still tastes of matcha and halves the caffeine.
2. Switch to hojicha after lunch. Ours carries 16 to 30 mg in a 2 g serve.
3. Try genmaicha. About 10 mg per 100 ml brewed, half of sencha.
4. Keep a daily tally. Coffee, cola, energy drinks and dark chocolate all count toward the 200 mg.
5. Have your last caffeine earlier. With a slower half life, a midday cutoff helps sleep.

Talk to your midwife or GP

Every pregnancy is different, and some people are advised to cut caffeine further. If you drink several caffeinated drinks a day, or you are unsure what counts, ask your care team. They can tailor the official limit to you.