In today’s post, we will talk about something really important: how drinking coffee during pregnancy could possibly increase the risk of stillbirths. There’s a new study1 out that clarifies whether caffeine can affect what happens during pregnancy. So let’s get started and understand this crucial issue.
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Is It Safe To Drink Coffee During Pregnancy: Study Overview
For quite some time now, scientists have been curious about how caffeine could possibly influence pregnancy. Past research has hinted at the idea that drinking too much caffeine might raise the risk of losing the baby early on.
Work’s been done with pregnant monkeys2 that suggests high caffeine intake might result in a stillbirth, which is the heartbreaking circumstance where a baby sadly passes away in the womb after being 28 weeks along.
But what role does caffeine play in that scenario? Some experts think that caffeine might stimulate the release of certain chemicals in the mom’s body, which could narrow blood vessels in the womb. This constriction could make it difficult for the baby to receive enough oxygen. Also, caffeine might directly impact the baby’s heart, causing irregular heartbeats.
However, it’s important to consider that women who drink a lot of coffee might also smoke and drink, which can also influence pregnancy outcomes. So this makes it hard to know whether caffeine is solely responsible for any problems.
Given these questions, researchers at Aarhus University Hospital in Denmark did a study. The research, involving 18,478 single-birth pregnancies done over seven years from 1989 to 1996, sought to provide a clearer picture of the possible implications and risks of drinking coffee while pregnant.
- Aarhus University studied 18,478 pregnancies to explore caffeine’s risks.
- Scientists wondered if excessive caffeine increased miscarriage and stillbirth risks.
- Does caffeine cause womb blood vessel constriction and irregular baby heartbeats?
- Separating caffeine’s effects from smoking and drinking is challenging.
The study participants, all women expecting a single baby, provided information about their health, age, and consumption of coffee and alcohol. Only those who completed the survey and had pregnancies lasting beyond 28 weeks were included, resulting in data from 18,478 pregnancies.
The women’s daily coffee intake was divided into four groups:
- 0 cups
- 1-3 cups
- 4-7 cups
- 8 or more cups
Each cup had around 100mg of caffeine. The study also collected data on tea, hot chocolate, and soda but didn’t analyze them much since not many women consumed high amounts.
To analyze the data, they used a method called multivariate logistic regression, which is like solving a puzzle by looking at different pieces (factors) simultaneously to get the complete picture.
They also attempted another analysis called Cox regression to explore if the timing of infant death after birth was related to coffee consumption. However, since it didn’t change the conclusions, they didn’t include those details.
Lastly, the study received ethical approval from the regional ethics committee, the Danish National Board of Health, and the Danish Data Protection Agency, ensuring it was conducted with proper authorization.
- Researchers studied how coffee in pregnancy impacts stillbirths, considering various factors.
- They analyzed multiple factors together, like a puzzle.
- The study had approvals, ensuring it was properly conducted.
The study clearly showed a direct correlation between the number of cups of coffee a pregnant woman drank and the risk of stillbirth (see Table 1). For instance, women with 4-7 cups of coffee daily had an 80% higher risk of stillbirth than those who didn’t drink coffee. Those who drank 8 or more cups had a massive 300% higher risk.
Table 1: Coffee’s impact on stillbirths
|Coffee/day||Women||Stillbirths / 1000|
|8 or more||950||11 (11.6%)|
The researchers also discovered that the women drinking a lot of coffee were likelier to smoke cigarettes and consume alcohol. They tended to be older, already had kids, were more likely to be single, less likely to be in school, and had fewer years of education (see Table 1).
Here’s where it gets even more interesting: when the researchers considered the women’s smoking and drinking habits, the stillbirth risk decreased slightly. Even after considering factors like the mom’s age, whether or not she was married, education, job status, and body mass index, the results stayed pretty much the same (see Table 2).
Table 2: Coffee’s impact on stillbirths, with and without considering other factors
|Coffee/day||Women||Stillbirths / 1,000||Smoking||Alcohol||All|
|0 cups||7,878||31 (3.9%)||Typical||Typical||Typical|
|1-3 cups||6,362||17 (2.7%)||Slightly Lower||Slightly Lower||Slightly Lower|
|4-7 cups||3,288||23 (7.0%)||Bit Lower (1.5x)||Bit Higher (1.6x)||Bit Lower (1.4x)|
|8+ cups||950||11 (11.6%)||Quite Higher (2.2x)||Quite Higher (2.6x)||Quite Higher (2.2x)|
In simpler terms, drinking lots of coffee seemed to be linked to stillbirth regardless of these other factors. When looking at infant death, it seemed that drinking eight or more cups of coffee a day doubled the risk. But, after considering whether or not the mom smoked, this link wasn’t clear anymore (see Table 3).
Lastly, the study noted that women who didn’t provide information on their coffee intake were more likely to smoke, be over 30, have more than one child, be unemployed, and have less education. However, not having the coffee data didn’t really affect the study’s main findings.
Table 3: Coffee’s impact on birthed infant deaths considering various factors
|Coffee/day||Women||Infant Deaths/1,000 Live Births||Smoking||Alcohol||All*|
|0 cups||7,847||34 (4.3%)||Typical||Typical||Typical|
|1-3 cups||6,345||27 (4.3%)||Slightly Lower||Same||Slightly Lower|
|4-7 cups||3,265||4 (1.2%)||Much Lower (0.2x)||Much Lower (0.3x)||Much Lower (0.2x)|
|8+ cups||939||9 (9.6%)||Bit Lower (1.6x)||Quite Higher (2.1x)||Bit Lower (1.6x)|
Conclusion & Takeaway
What can we infer from this study? Pregnant women who consume eight or more cups of coffee daily have more than twice the risk of experiencing a stillbirth compared to those who do not drink coffee during pregnancy. However, it doesn’t seem to impact the likelihood of an infant passing away in the first year of life.
Now, the study isn’t perfect. They asked women about their coffee drinking habits 16 weeks into their pregnancies, and there’s a chance that they might not have remembered accurately. They also didn’t have details on the size of the coffee cups or the kind of coffee, which can make a difference in how much caffeine is in there.
Another point to consider is that the study was done in an area where there were not a lot of stillbirths, to begin with, so it’s hard to say if these findings would be the same in different communities or populations. In a nutshell, it might be a good idea to think about cutting back on the java while expecting to be on the safe side.
For those who are interested in reading the full study, you can access it here.
- Wisborg, K., Kesmodel, U., Bech, B. H., Hedegaard, M., & Henriksen, T. B. (2003). Maternal consumption of coffee during pregnancy and stillbirth and infant death in first year of life: Prospective study. BMJ : British Medical Journal, 326(7386), 420. https://doi.org/10.1136/bmj.326.7386.420
- Gilbert SG, Rice DC, Reuhl KR, Stavric B. Adverse pregnancy outcome in the monkey (Macaca fascicularis) after chronic caffeine exposure. https://pubmed.ncbi.nlm.nih.gov/3385636/ J Pharmacol Exp Ther. 1988;245:1048–1053.