Moderate Coffee Intake Safe in Late Pregnancy

If you’ve been avoiding your usual coffee in your third trimester because you’re worried it might affect your baby’s birth weight or lengthen your pregnancy, you’re not alone. Many pregnant women wonder whether any amount of caffeine is safe during late pregnancy. But what does the science actually say?

In short: yes, moderate daily caffeine intake — around 3 or fewer cups of regular coffee worth per day — appears safe in late pregnancy, according to a rigorous Danish clinical trial. It did not significantly affect either birth weight or pregnancy length.

The Danish Study on Caffeine and Late Pregnancy

Published online in the BMJ on January 26, 2007, a double-blind, randomised, controlled study led by researchers at Aarhus University in Denmark investigated the effects of caffeine consumption during the third trimester. The team enrolled 1,207 pregnant women, all of whom reported drinking at least three cups of coffee per day prior to the study. Participants were randomly assigned to receive either caffeinated or decaffeinated coffee, allowing researchers to compare outcomes while keeping other variables consistent.

How the Study Worked

Women were given identical-looking coffee — some caffeinated, some decaffeinated — and instructed to consume it as part of their normal routine. The caffeinated group (568 women) received coffee with typical caffeine levels, while the decaffeinated group (629 women) received coffee with negligible caffeine content. Researchers tracked two main outcomes: the length of pregnancy and the birth weight of single babies born to these mothers. They also precisely measured the actual caffeine intake of participants to assess differences.

Key Findings on Birth Weight and Pregnancy Duration

Of the 1,150 singletons delivered, the average birth weight was 7.8 pounds (3.54 kg) in the caffeinated group and 7.75 pounds (3.51 kg) in the decaffeinated group — a difference of just 0.05 pounds, which was not statistically significant. Similarly, the average pregnancy duration was just 1.31 days shorter in the decaffeinated group compared to the caffeinated group across 1,153 mothers, again a non-significant difference. On average, the decaffeinated group consumed 182 mg less caffeine per day than the caffeinated group.

What This Means for Pregnant Coffee Drinkers

The study suggests that consuming moderate amounts of caffeine — equivalent to around three cups of coffee per day — during the third trimester does not meaningfully influence either how long your pregnancy lasts or how much your baby weighs at birth. However, the research focused solely on the third trimester and moderate intake levels.

Frequently Asked Questions

Is it safe to drink caffeinated coffee in the third trimester?

Yes, this study found that drinking caffeinated coffee with around 3 cups’ worth of caffeine per day (roughly 182 mg more than the decaf group) during the third trimester did not significantly affect birth weight or pregnancy duration. However, 'safe' does not mean 'risk-free' for everyone, and individual tolerance varies.

How much caffeine did the women in the study actually consume?

The caffeinated group consumed more caffeine than the decaffeinated group by about 182 mg per day on average. While the exact number of cups wasn’t specified, this roughly equates to 3 or more standard cups of brewed coffee, depending on preparation.

Did coffee affect how long the pregnancies lasted?

The difference in pregnancy duration between the decaffeinated and caffeinated groups was just 1.31 days, which was not statistically significant. Therefore, moderate caffeine intake did not meaningfully change how long women carried their pregnancies in this study.

What about the baby’s birth weight?

The average birth weight was 7.8 pounds in the caffeine group and 7.75 pounds in the decaf group — a negligible difference of 0.05 pounds (22 grams), which is not clinically or statistically significant.

Does this study cover early pregnancy or high caffeine intake?

No. This research only examined the third trimester and moderate caffeine intake (about 3 cups/day). It did not address caffeine safety in the first or second trimesters, or the effects of very high caffeine consumption during pregnancy.

Should I switch to decaf if I’m pregnant?

The study suggests moderate caffeine is safe in late pregnancy, but experts still recommend limiting intake. Women with a history of miscarriage or pregnancy complications may especially benefit from a decaffeinated diet. Always consult your healthcare provider.

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