The Latest on Caffeine and Pregnancy

by Kathryn Davis, BS, LMT

Caffeine consumption during pregnancy has been studied for decades with inconsistent results. Recent research is leaning towards the conclusion that there is no association between caffeine intake and preterm delivery. And, some research even suggests that as many as twelve 8-ounce cups of coffee per day can be ingested with no ill effect. Let’s take a look at caffeine and its effects so you can make an informed decision.

What is caffeine? At a basic level, caffeine is a naturally occurring stimulant found in over 60 plants, all over the world. Chemically speaking, caffeine is an alkaloid- a chemical made by a plant that contains nitrogen. Caffeine is just one of many chemicals belonging to the alkaloid family. Other alkaloids include: nicotine, cocaine, and methamphetamine. Because of it’s legality and availability, according to, caffeine is the most widely used psychoactive substance in the world.

Once caffeine is consumed, it is rapidly absorbed by the stomach and small intestines where it is distributed to all body tissues and fluids- including the bloodstream, fetal tissues, and breastmilk. You can begin feeling the effects of caffeine as soon as 15 minutes after ingestion. The stimulant effects usually “peak” within 30 minutes to an hour after ingestion. Once consumed, caffeine sticks around for hours- it takes about 6 hours for ½ of the caffeine ingested to be eliminated, although you will have stopped feeling the effects long before. Caffeine is metabolized, processed by the liver, and excreted through urine.

Caffeine stimulates the central nervous system (CNS), increasing blood pressure and heart rate. It also stimulates the cardiovascular system- increasing blood flow and breathing rate. It can increase metabolic rate for several hours after ingestion, elevate mood, increase alertness, and decrease fatigue. In addition to some of what may be seen as positive effects, caffeine can also cause stomach upset, nervousness, irritability, headaches, insomnia, and diarrhea- especially if too much is consumed. Caffeine is a diuretic- increasing the frequency of urination which can cause reduction in body fluid levels and possibly lead to dehydration. Caffeine ingestion, even in moderate consumption, can interfere with nutrient metabolism and absorption. Caffeine increases the excretion of calcium, an important mineral in bone health and muscle contraction, and also interferes with the absorption of iron.

What does ingesting caffeine mean for women who are pregnant? The stimulation to maternal CNS affects the developing fetus. An increase in maternal blood pressure and heart rate will also increase the blood pressure and heart rate of the developing baby. Anything ingested, including caffeine, does cross the placenta and, since systems  for breaking down and eliminating chemicals are not fully developed in a developing fetus, the unborn child may have a more difficult time breaking down substances like caffeine. Caffeine metabolism dramatically slows during pregnancy. The metabolic rate drops progressively, falling to one-half of normal during the second trimester, and to one-third of normal during the third trimester. This means that caffeine that is ingested by the woman in the last few
months of pregnancy will remain in her system three times longer than usual and, consequently, that the exposure of the unborn child to caffeine will last three times longer.

Many women are concerned about the association of caffeine with preterm labor or miscarriage. Also of concern, and debate, is the effect of caffeine on birth weight and birth abnormalities. Research is generally inconclusive on these topics. The general recommendation for pregnant women is that moderate amounts of caffeine during pregnancy are okay. A moderate level of caffeine is considered 200 mg or less. 200 mg of caffeine is about the amount in a 12-ounce cup of coffee, or would also include drinking about four 8-ounce cups of tea, or more than five 12-ounce cans of soda a day, or eating six or seven dark chocolate bars. The amount generally recognized as safe for non-pregnant, healthy adults is 400mg or less per day. This amount reflects the amount that can be ingested without adverse effects such as general toxicity, and effects on bone status and calcium balance (with consumption of adequate calcium).

While the research may be inconclusive, there are clear negative effects to consuming caffeine, even if not pregnant. Consciousness in consumption is the key to health for you and your baby.

Kathryn Davis, BS, LMT is a nutritionist, yoga instructor, and massage therapist in the Portland area.

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