Women give up a lot of foods and soft drinks during pregnancy, either because they cannot tolerate them or because of the potentially harmful effects on the baby. Giving up the occasional sushi and mayonnaise may be easy, but what about the morning cup of coffee?
How caffeine affects the mother
Everyone knows that the daily cup of coffee is addictive. Caffeine is actually the most common drug in the world, and among the few that are socially acceptable.
Caffeine is a stimulant and it increases the heart rate as well as blood pressure. So does pregnancy, because the heart needs to pump more blood to the unborn baby as it grows.
Caffeine also has diuretic effects, meaning that it speeds the elimination of water from the body. In extreme case, this can lead to dehydration. In contrast, the body needs extra water during pregnancy, to ship all the nutrients, prenatal vitamins, and minerals to the developing fetus.
How caffeine affects the baby
Caffeine is rapidly absorbed by the mother’s body and easily crosses the placenta.
However, the primary enzyme that helps with the metabolism of caffeine is absent from the placenta and the fetus. Thus, the amount of caffeine and how fast it is cleared from the body (and the fetus) depends on the mother’s metabolism. There are a lot of factors which can influence metabolisms like smoking, alcohol, liver disorders, some drugs, and even grapefruit.
Moreover, pregnancy slows down caffeine clearance from the body. As a general rule, the effect of caffeine reaches its peak about 30 minutes to one hour after ingestion, and it lasts for three to nine hours, depending on the metabolism of each person.
In the case of pregnant women, though, caffeine half-life extends to about 11.5-18 hours by the end of pregnancy. This is a lot and means that daily consumption of coffee can lead to the accumulation of caffeine in the body.
Therefore, as there is a permanent stock of caffeine in the mother’s body, the fetus will, in turn, continuously consume caffeine. The natural consequence is that the unborn baby will be overstimulated all the time. This brings us to two of the most common side effects of caffeine for the fetus: irregular heart rate and sleep disturbances.
If caffeine intake is particularly high (more than 300 mg per day) during the entire pregnancy, newborns can experience withdrawal symptoms immediately after birth. These signs include irritability, agitation, and even vomiting.
Other potential side effects studies by scientists are low birth weight, the risk of miscarriage, and of preterm labor.
As for low birth weight, several studies have concluded that there is a link between fetus growth restriction and caffeine intake and that the odds increase proportionally with daily caffeine consumption.
Nonetheless, caffeine in itself does not decrease blood flow to the uterus or fetus oxygenation, therefore, in theory, it should not lead to a birth weight that is below average. As such, scientists have not arrived at a definite conclusion on this matter.
The risk of miscarriage is also not clearly linked to drinking coffee in large quantities. The American College of Obstetricians Gynecologists (ACOG) says that research about the correlation between high caffeine consumption and miscarriage has proved inconclusive. This is because studies in this field have been small in size or the data quality was poor (for instance, some mothers also smoked or did not measure their caffeine intake correctly).
The risk of preterm labor does not seem to be a significant risk factor in case of heavy coffee drinkers.
According to research, there is no significant correlation between caffeine exposure and delivering a preemie.
What amount of caffeine is safe for the baby?
While experts have not come to a clear-cut conclusion on essential risks like low birth weight and the risk of miscarriage, research concludes that drinking moderate amounts of coffee is safe during pregnancy.
Thus, according to the American College of Obstetricians Gynecologists (ACOG), consuming up to 200 mg of caffeine per day is not a significant factor in preterm birth or miscarriage. To put this into perspective, one or two cups of coffee per day should be ok.
Tented for more? There are conflicting and limited studies on women consuming more than 300mg per day, which corresponds to 3 cups of instant coffee per day.
Sources of caffeine
Computing the daily caffeine intake can be tricky because one aspect we often forget is that there are other energizing drinks or sweets that we consume, besides coffee. Unfortunately, some of them also contain caffeine; naturally, they should be taken into account when computing the daily caffeine intake.
Caffeine is found also in tea, cola drinks, soft drinks, energy drinks, hot chocolate, and chocolate.
According to the US Food & Drug Administration, a 12-ounce soft drink contains 30-40 milligrams of caffeine, an 8-ounce green or black tea has 30-50 milligrams, an 8-ounce regular coffee provides 80-100 milligrams, and an 8-ounce energy drink comes with 40-250 milligrams of caffeine.
The amount of caffeine in beverages varies because it depends on the variety of coffee and tea plants, and on how coffee beans were processed and tea leaves grown.
To summarize:
- caffeine does not benefit the baby
- a lot of research papers show conflicting results on the side effects of caffeine during pregnancy…
- …but enough studies are concluding that it is risky to have more than 300mg of caffeine per day
- limiting the daily amount of caffeine to maximum 200mg is considered safe.
