Caffeine intake in pregnancy

Moderate daily caffeine intake during pregnancy may lead to smaller birth size

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Thursday, March 25, 2021

Pregnant women who consumed the caffeine equivalent of as little as half a cup of coffee a day on average had slightly smaller babies than pregnant women who did not consume caffeinated beverages, according to a study by researchers at the National Institutes of Health. The researchers found corresponding reductions in size and lean body mass for infants whose mothers consumed below the 200 milligrams of caffeine per day — about two cups of coffee — believed to increase risks to the fetus. Smaller birth size can place infants at higher risk of obesity, heart disease and diabetes later in life.

The researchers were led by Katherine L. Grantz, M.D., M.S., of the Division of Intramural Population Health Research at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development. The study appears in JAMA Network Open.

“Until we learn more, our results suggest it might be prudent to limit or forego caffeine-containing beverages during pregnancy,” Dr. Grantz said. “It’s also a good idea for women to consult their physicians about caffeine consumption during pregnancy.”

Previous studies have linked high caffeine consumption (more than 200 milligrams of caffeine per day) during pregnancy to infants being small for their gestational age (stage of pregnancy) or at risk for intrauterine growth restriction—being in the lowest 10th percentile for infants of the same gestational age. However, studies on moderate daily caffeine consumption (200 milligrams or less) during pregnancy have produced mixed results. Some have found similar elevated risks  for low birth weight and other poor birth outcomes, while others have found no such links. The current study authors noted that many of the earlier studies did not account for other factors that could influence infant birth size, such as variation in caffeine content of different beverages and maternal smoking during pregnancy.

For their study, the authors analyzed data on more than 2,000 racially and ethnically diverse women at 12 clinical sites who were enrolled from 8 to 13 weeks of pregnancy. The women were non-smokers and did not have any health problems before pregnancy. From weeks 10 to 13 of pregnancy, the women provided a blood sample that was later analyzed for caffeine and paraxanthine, a compound produced when caffeine is broken down in the body. The women also reported their daily consumption of caffeinated beverages (coffee, tea, soda and energy drinks) for the past week—once when they enrolled and periodically throughout their pregnancies.

Compared to infants born to women with no or minimal blood levels of caffeine, infants born to women who had the highest blood levels of caffeine at enrollment were an average of 84 grams lighter at birth (about 3 ounces), were .44 centimeters shorter (about .17 inches), and had head circumferences .28 centimeters smaller (about .11 inches).

Based on the women’s own estimates of the beverages they drank, women who consumed about 50 milligrams of caffeine a day (equivalent to a half cup of coffee) had infants 66 grams (about 2. 3 ounces) lighter than infants born to non-caffeine consumers. Similarly, infants born to the caffeine consumers also had thigh circumferences .32 centimeters smaller (about .13 inches).

The researchers noted that caffeine is believed to cause blood vessels in the uterus and placenta to constrict, which could reduce the blood supply to the fetus and inhibit growth. Similarly, researchers believe caffeine could potentially disrupt fetal stress hormones, putting infants at risk for rapid weight gain after birth and for later life obesity, heart disease and diabetes.

The authors concluded that their findings suggest that even moderate caffeine consumption may be associated with decreased growth of the fetus.

About the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD): NICHD leads research and training to understand human development, improve reproductive health, enhance the lives of children and adolescents, and optimize abilities for all. For more information, visit https://www.nichd.nih.gov.

About the National Institutes of Health (NIH): NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.

NIH…Turning Discovery Into Health^®

References

Gleason, JL et al. Maternal caffeine consumption and metabolism and neonatal anthropometry in the NICHD Fetal Growth Studies. JAMA Network Open. 2021. doi:10.1001/jamanetworkopen.2021.3238

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Regular Consumption of Low Levels of Caffeine During Pregnancy Linked to Slightly Shorter Children

Exposure to caffeine in the womb, even low amounts, may lead to shorter height in childhood, suggests a new study from the National Institutes of Health (NIH). Children of women with low caffeine intake (including below the current recommendation of 200 milligrams [mg] per day) during pregnancy were slightly shorter than children born to women who consumed no caffeine while pregnant, and the gaps in height widened to 2 centimeters (cm) between ages 4 and 8 years old. The findings were published October 31 in JAMA Network Open.

“Our findings suggest that even low caffeine intake during pregnancy can have long-term effects on child growth,” said the co-lead author, Katherine Grantz, MD, in a press release.

It’s important to note that the observed height differences were small — less than an inch — and further research is needed to determine if these differences have any effect on child health, said Dr. Grantz. “Pregnant people should discuss caffeine consumption with their healthcare providers,” she said.

Current guidelines on caffeine consumption during pregnancy recommend that women consume less than 200 mg per day, the amount in a typical 12 ounce (oz) cup of coffee. Tea, energy drinks, soft drinks, and chocolate all contain varying amounts of caffeine.

Those guidelines are based on research that suggests that less than 200 mg of caffeine per day does not cause miscarriage or preterm birth, according to the American College of Obstetricians and Gynecologists (ACOG).

But further study is needed to see if exposure to caffeine while in the womb has any impact on the child after they are born. NIH research published on March 25, 2021, in JAMA Network Open found that moderate caffeine intake during pregnancy may lead to smaller birth size.

To assess how maternal caffeine consumption might impact the height, weight, body mass index (BMI) and obesity risk of the children, researchers analyzed concentrations of caffeine and its breakdown product, paraxanthine, in blood samples collected from 2,410 pregnant women in two previous studies, the Environmental Influences on Child Health Outcomes (ECHO) study and the Collaborative Perinatal Project (CCP).

To better isolate the impact of caffeine, they controlled for several other factors that could affect child growth, including maternal height, pre-pregnancy weight and smoking status.

While the researchers didn’t find that the caffeine consumption of the moms-to-be made a difference in weight, BMI, or obesity risk of the children, they did find a connection between higher maternal caffeine consumption and shorter height in both study populations.

Among the 788 children in the ECHO study, those born to women who consumed the greatest amounts of caffeine were an average of 1.5 cm shorter than those whose mothers had the lowest caffeine intake. On average, pregnant women in the study consumed less than 50 mg per day of caffeine. Child growth was measured once, at an average age of 7 years.

The children in the CCP study (1,622 mother-child pairs) were measured at regular intervals from birth to age 8, allowing researchers to track changes in height over time. Caffeine consumption by the pregnant women was higher in this group, averaging around 200 mg a day.

Beginning at age 4, children of women who consumed the highest amounts of caffeine were shorter than those born to women in the lowest caffeine-consumption group, a gap that increased from 0.68 cm at age 4 to 2.2 cm at age 8.

The study found that small daily amounts of caffeine during pregnancy were associated with shorter child stature that continued at least through age 8, wrote the researchers.

“Future research on caffeine consumption during pregnancy should follow child growth over time to determine whether these height gaps continue into adulthood and if they are linked to a greater risk of cardiometabolic diseases,” said the study coauthor Jessica Gleason, PhD, MPH, in the press release.

Although this was a well-designed and well-executed study, the findings on height lack clinical significance, says Talla Motakef Widelock, MD, an obstetrician-gynecologist at Atrium Health Wake Forest Baptist in Winston-Salem, North Carolina, who was not involved in the research.

“For example, if the children were found to have a BMI that indicated they were below or above a healthy weight, that could impact their health,” says Dr. Widelock. “But a 2 cm difference in height — less than an inch — in this specific age group of 4 to 8 years old — that hasn’t been shown to impact health,” she says.

And although the investigators did try to control for several factors, there are many things that may impact children’s height at that age that were not included in the study, such as the height of the father, notes Widelock.

Each woman should talk with her provider to decide a safe level of caffeine consumption during pregnancy, says Widelock.

“On the basis of these findings, I would not change my current recommendations around caffeine consumption to my patients. Right now, we don’t know of any adverse outcomes from consuming less than 200 mg of caffeine a day — and that’s the current guidance,” she says.

Although these findings are interesting, there’s still a lot more research to be done before we determine if there’s any long-term adverse outcomes for children because of this level of caffeine consumption, says Widelock.

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Coffee during pregnancy: a complete guide to all the do's and don'ts

When a woman sees "two lines" on her test, her life begins to change that same day. In this life, there are more good habits (timely sleep, proper nutrition, moderate exercise) and less bad habits (alcohol, smoking, sedentary lifestyle, unhealthy food). Coffee as a potentially dangerous product, around which there is a lot of controversy, often falls under the barrier of prohibitions.

Even without any pregnancy, coffee often raises a number of questions and concerns among people, so the debate around this drink is quite understandable and justified. But our task is to separate myth from reality and figure out when restrictions make sense and when they are a pointless obstacle to a fulfilling joyful lifestyle.

How does coffee affect the body of a pregnant woman?

Before talking about some special effect of coffee on a pregnant woman, let's refresh our memory of what actually happens to us when we drink coffee:

• After caffeine enters the blood, dopamine is released, which, as we remember, is responsible for a good mood. This hormone of joy very willingly “jumps out” in response to a shot of espresso or cappuccino and makes us feel good.
• Under the influence of dopamine, we find it easier to play sports, we become more enduring and notice less pain in the muscles. It also improves overall performance.
• If there is too much caffeine (read - dopamine), the suppression of serotonin production begins. This leads to increased anxiety and can provoke depression. nine0012
• In parallel, under the influence of caffeine, adrenaline is released, another hormone that is responsible for our good mood and cheerfulness.
• Increased concentration.
• In most cases, coffee stimulates our heart to beat faster. The rhythm of the heartbeat accelerates and at the same time the pressure rises.
• The theophylline contained in coffee acts on the intercostal muscles and muscles of the diaphragm, as a result of which our breathing becomes more relaxed and easier. nine0012
• The excretory systems (diuretic and intestines) are stimulated - under the influence of caffeine, we feel the desire to visit the restroom faster.
• Caffeine also stimulates the nervous system. The peak of this action occurs in the first hour or two after drinking coffee, then for an average of 3-4 hours the breakdown of caffeine in the blood occurs, at which time many people have difficulty falling asleep.

What changes when a pregnant woman drinks coffee? In addition to the above phenomena, the following important parameters should be additionally indicated:

• slows down the process of removing caffeine from a woman's body;
• increased fetal heart rate;
• increased fetal activity;
• Excessive use creates possible risks for the child.

It is the last item on this list that is cause for concern and doubt about the admissibility of coffee in the diet of a pregnant woman. Below we describe in detail what these risks are and in what cases concerns can be justified. nine0003

Can pregnant women drink coffee?

Let's start with a high-profile peer-reviewed study published in the BMJ Evidence-Based Medicine. Professor Jack James from Reykjavik University in Iceland conducted a series of studies in 2020 and concluded that there is no safe level of caffeine intake for pregnant women: even the smallest amount can negatively affect the development of the fetus. However, Mr. James' colleagues from other countries categorically disagree with him. The National Health Service, the European Food Safety Authority, and the American and British Colleges of Obstetricians and Gynecologists recommend limit but not eliminate caffeine intake during pregnancy . The research paper was deemed "too panicky" and inconsistent with the accepted evidence.

“There are so many do's and don'ts associated with pregnancy, and the last thing we want to do is cause unnecessary worry. After all, women need to be sure that caffeine can be consumed in moderation during pregnancy,” says Dr. Luc Grzeskowiak, a pharmacist at the University of Adelaide in Australia. nine0052