Can Pregnant Women Drink Coffee in Their Third Trimester?

If you’re pregnant and craving your usual cup of coffee, you’re not alone. Many expecting mothers wonder whether drinking coffee—especially in the third trimester—could harm their baby or affect labor. The good news? New research offers clear, evidence-based guidance.

The short answer: Yes, pregnant women in their third trimester can drink moderate amounts of coffee without affecting birth weight or how long they stay pregnant. A key Danish study found no significant difference in outcomes between those consuming caffeinated and decaffeinated coffee.

The Danish Study on Caffeine and Late Pregnancy

Published in the BMJ on January 26, 2007, this double-blind, randomised, controlled trial involved 1,207 pregnant women. All participants reported drinking at least three cups of coffee daily before the study. Researchers then divided them into two groups: one continued with regular caffeinated coffee (568 women), while the other switched to decaffeinated coffee (629 women).

The study specifically focused on the third trimester, a critical period for fetal growth and preparation for birth. Participants were monitored through delivery, with researchers tracking both gestational length and newborn birth weight.

What the Numbers Show

On average, women in the decaffeinated group consumed 182 mg less caffeine per day than those in the caffeinated group. Despite this difference, outcomes were remarkably similar:

• The average birth weight of single babies was 7.8 pounds (3.54 kg) in the caffeinated group and 7.75 pounds (3.52 kg) in the decaffeinated group—no statistically significant difference.
• Gestational age at birth averaged just 1.31 days shorter in the decaffeinated group, again not a meaningful or statistically significant gap.

Out of the 1,150 singletons delivered, none showed significant variation in birth metrics due to the mother’s caffeine intake level during the third trimester.

What This Means for Pregnant Coffee Drinkers

Researchers concluded that moderate caffeine consumption during the third trimester does not meaningfully influence either how long a woman is pregnant or how much her baby weighs at birth. That said, the study did not examine very high levels of caffeine intake or the effects of caffeine consumption in the first or early second trimester—periods when the fetus is more vulnerable to external influences.

Medical experts still recommend that pregnant women limit caffeine as a precaution. For those with a history of miscarriage or difficulty conceiving, avoiding caffeine entirely—or sticking strictly to decaf—is strongly advised.

Frequently Asked Questions

How much caffeine did the women in the study consume?

Women in the caffeinated group consumed roughly 182 mg more caffeine per day than those in the decaffeinated group. While the exact milligrams aren’t specified for each group, this difference reflects typical amounts found in three or more cups of standard brewed coffee.

Did coffee affect the baby’s birth weight?

No. The average birth weight was 7.8 pounds in the caffeinated group and 7.75 pounds in the decaffeinated group. The difference is not statistically significant.

Did caffeine change the length of pregnancy?

Not in a meaningful way. The decaffeinated group’s pregnancies averaged 1.31 days shorter, but this difference is too small to be considered clinically or statistically significant.

Is it safe to drink coffee in the first trimester?

This study only examined the third trimester. It did not assess the safety of caffeine intake in the first or early second trimester, which are more sensitive developmental periods.

Should women with pregnancy complications avoid caffeine?

Yes. Experts recommend that women who have experienced miscarriage or have had trouble conceiving should avoid or strictly limit caffeine, ideally choosing decaffeinated coffee instead.

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