How Many Cups of Coffee a Day During Pregnancy and Breastfeeding? The 200 mg Guideline and Caffeine Half-Life on the Pill
Many people who are pregnant or breastfeeding wonder whether to give up coffee entirely, or how many cups are fine. Health authorities abroad give 200 mg a day (about 2 cups of drip coffee) as a guideline, but in pregnancy caffeine takes longer to leave the body, so it helps to think about timing as well as amount. This article sets out, with numbers, the guidelines for pregnancy and breastfeeding and the reasons behind them, how a longer half-life in pregnancy changes the amount left at night, and how taking low-dose birth control pills or quitting smoking changes the half-life.
200 mg a day is the guideline in pregnancy and breastfeeding
Caffeine crosses the placenta and reaches the baby. A baby in the womb has almost no ability to break caffeine down, so during pregnancy it's recommended to take less than the usual adult guideline. Japan has no official standard, but agencies abroad give the following guidelines.
| Agency | Daily guideline in pregnancy |
|---|---|
| European Food Safety Authority (EFSA) | Up to 200 mg (same for breastfeeding) |
| UK National Health Service (NHS) and others | Up to 200 mg |
| Health Canada | Up to 300 mg |
| World Health Organization (WHO) | Up to 300 mg |
If in doubt, the more cautious 200 mg is the safer guideline. Large amounts of caffeine have been linked to a higher risk of miscarriage and low birth weight, but moderate amounts up to about 200 mg are not considered a concern. If you're worried, or if you have morning sickness, a medical condition or take medication, talk to your doctor or midwife at your antenatal check-ups.
How many cups is 200 mg?
| Drink (one serving) | Caffeine | Servings up to 200 mg |
|---|---|---|
| Drip coffee 150 ml | About 90 mg | 2.2 cups |
| Instant coffee 140 ml (2 g powder) | About 80 mg | 2.5 cups |
| Caffè latte (1 shot of espresso) | About 80 mg | 2.5 cups |
| Black tea 150 ml | About 45 mg | 4.4 cups |
| Sencha or hojicha 120 ml | About 24 mg | 8.3 cups |
| Gyokuro 60 ml | About 96 mg | 2.0 cups |
| Bottled oolong tea 500 ml | About 100 mg | 2.0 bottles |
| Cola 350 ml | About 39 mg | 5.1 cans |
That's about 2 cups of drip coffee or about 4 cups of black tea a day. A mug of coffee (about 300 ml) contains about 180 mg, so count it as your one cup for the day. Some bottles of green or oolong tea contain around 100 mg each, so if you drink them instead of water you can easily exceed the guideline without realising. Amounts for other drinks are listed in caffeine content by drink.
Pregnancy makes caffeine harder to clear
During pregnancy, hormones gradually slow the rate at which the liver breaks down caffeine. Not much changes in early pregnancy, but the half-life lengthens through the second and third trimesters, reaching around 15 hours in late pregnancy, three times the roughly 5 hours of a typical adult.
Here's how much the amount left at night changes for the same drinking pattern (the calculation includes the time taken for absorption).
| Drinking pattern | Half-life 5 hours (before pregnancy) | Half-life 15 hours (late pregnancy) |
|---|---|---|
| 1 cup of drip coffee at 8:00 → left at 22:00 | About 13 mg | About 48 mg |
| 1 cup each at 8:00 and 13:00 → left at 22:00 | About 40 mg | About 108 mg |
| Time until 1 cup of drip coffee drops to 50 mg or less | About 4.5 hours | About 13 hours |
In late pregnancy, even a single morning cup leaves more than half its caffeine in your body by night, and two cups leave over 100 mg at bedtime. Pregnancy is already a time when you tend to wake up often and sleep lightly. Even if you stay within 200 mg a day, having your caffeine in the morning and switching to caffeine-free drinks in the afternoon reduces the effect on your sleep. If you go to bed at 23:00, keeping one cup of drip coffee to 50 mg or less at bedtime with a 15-hour half-life means drinking it by about 10:00.
Caffeine while breastfeeding, and when to drink it
A small amount of the caffeine you take in while breastfeeding passes into breast milk. The amount is tiny, but newborns are poor at breaking caffeine down, and their half-life is said to stretch to several days. Their ability to break it down approaches adult levels by about 3 to 5 months of age.
- The daily guideline is 200 mg, the same as in pregnancy (EFSA)
- Caffeine in breast milk peaks about 1 hour after you drink it. If you drink it right after a feed, the amount in your body will have fallen by the next feed
- If your baby won't settle, is fussy or seems restless, cut down on caffeine and see if it helps
- Keep it especially low in the first weeks after birth or if your baby was born prematurely
While breastfeeding, the half-life returns to its pre-pregnancy value as your body recovers after giving birth. In the Caffeine Calculator, calculate with the standard 5 hours, and during periods with lots of night feeds, setting the bedtime target to 25 mg makes it easier to protect your own sleep too.
On low-dose birth control pills, the half-life roughly doubles
Oral contraceptives (low-dose birth control pills) weaken the liver's ability to break down caffeine, roughly doubling its half-life to about 10 hours. That's why some people find that "since starting the pill, an afternoon coffee keeps me awake".
| Comparison | Half-life 5 hours | Half-life 10 hours (on the pill) |
|---|---|---|
| 1 cup of drip coffee at 15:00 → left at 23:00 | About 31 mg | About 53 mg |
| Bedtime at 23:00: latest time for 1 cup of drip coffee (50 mg or less) | 18:30 | 14:16 |
| Time until 1 cup of drip coffee drops to 25 mg or less | About 9.5 hours | About 18 hours 45 minutes |
If you take the pill, a good rule of thumb is to bring your coffee cut-off about 4 hours earlier than usual, to early afternoon. The same applies to low-dose pills prescribed for painful periods (LEP).
Smoking shortens the half-life, and quitting suddenly lengthens it
Unlike the pill, substances in tobacco smoke speed up the liver's breakdown enzymes, so smokers' caffeine half-life tends to be short, about 3 hours. That's why smokers can drink plenty of coffee and feel fine: the caffeine leaves their body quickly.
The thing to watch is quitting. The rate of breakdown returns to normal within a few days, so the same amount of coffee leaves more caffeine in your body. For someone who drinks a cup of drip coffee at 8:00, 12:30 and 15:00, the amount left at 23:00 is about 27 mg with a 3-hour half-life, but about 64 mg, more than double, once it returns to 5 hours. Palpitations, irritability and trouble falling asleep while quitting can actually be due to too much caffeine, so try cutting down on coffee when you stop smoking.
Drinks for when you want to cut down on caffeine
- Barley tea, rooibos, corn tea and black soybean tea: no tea leaves, so no caffeine
- Decaf (caffeine-free) coffee: at least 90% of the caffeine removed; up to about 9 mg per cup
- Bancha and genmaicha: relatively low at about 10 mg per 100 ml (but not zero)
- Herbal teas: caffeine-free, but some kinds are best avoided in pregnancy, so check the ingredients
FAQ
- How many cups of coffee a day can I drink while pregnant?
- Using EFSA's guideline of 200 mg a day, that's about 2 cups of drip coffee (about 90 mg per 150 ml). Health Canada and the WHO use 300 mg, but if in doubt, 200 mg is the safer guideline. Remember to add up caffeine from black tea, green tea, cola and chocolate too.
- Does caffeine take longer to clear during pregnancy?
- Yes. As pregnancy progresses, the liver breaks down caffeine more slowly, and in late pregnancy the half-life is said to stretch to around 15 hours. One cup of drip coffee at 8 a.m. works out to about 48 mg still in your body at 10 p.m., so it's best to have your caffeine in the morning.
- How long should I wait after coffee before breastfeeding?
- Caffeine in breast milk peaks about 1 hour after drinking, so it's best to drink right after a feed. With a 5-hour half-life, about 70% of what you drank is still in your body after 3 hours, so rather than waiting, focus on drinking right after a feed and staying within 200 mg a day.
- Does the pill make caffeine's effects stronger?
- Low-dose birth control pills (oral contraceptives) slow the breakdown of caffeine and roughly double its half-life to about 10 hours. A cup of drip coffee at 15:00 works out to about 53 mg left at 23:00. If you're finding it harder to sleep, have coffee only until early afternoon, or drink less.
- Why can't I sleep after coffee since I quit smoking?
- Tobacco speeds up caffeine breakdown, so while smoking your half-life is short, about 3 hours. After quitting, breakdown returns to its normal speed and the same amount of coffee can leave more than twice as much in your body at night. Cutting down on coffee while quitting can ease sleeplessness and palpitations.
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