Caffeine during pregnancy - babies 66 percent more likely to become overweight

By Dr. Ananya Mandal, MDApr 25 2018

A new study has shown that babies carry a 30 percent increased risk of being overweight when they are exposed to two cups of coffee daily while within the mother’s womb. If the mothers were consuming more than three cups of coffee a day while they were pregnant, the babies were 66 percent more likely to become overweight.

The study titled “Maternal caffeine intake during pregnancy and childhood growth and overweight: results from a large Norwegian prospective observational cohort study,” was published this week in the journal BMJ Open.

The team of Norwegian researchers noted that very high levels of caffeine in the material blood before birth of the baby leads to an average of at least one pound of increased weight when the children were eight years old. They suggest a complete avoidance of caffeine during pregnancy. Dr Eleni Papadopoulou, of the Norwegian Institute of Public Health in Oslo says that caffeine during pregnancy can affect a child’s weight growth up until the child is eight years. According to the NHS recommendations, women should drink no more than two cups of coffee during pregnancy. But Dr Papadopoulou suggests complete avoidance to reduce the risk of obesity.

There have been studies showing that excess caffeine during pregnancy can increase the risk of miscarriages and also lead to pregnancy health problems and low birth weight in the baby. The team thus went on to look at the effects of caffeine on the infants as they grew and found that no amount of coffee during pregnancy was safe. Dr Papadopoulou explained that during pregnancy the caffeine is eliminated slowly from the body. This means that it stays in the body and crosses the placental barrier easily reaching the baby. Within the baby, the caffeine freely passes into the brain crosses the blood brain barrier. This results in exposure of the fetus. According to her authorities have said that caffeine levels for pregnant women should not exceed 200 mg/day to prevent miscarriage and restriction of growth of the baby within uterus. This was one of the largest studies that explored the effects of caffeine on the child’s growth and development.

For this study the team looked at 50943 pairs of mothers and their babies who were participating in a Norwegian health study called “The Norwegian Mother and Child Cohort Study” between 2002 and 2008. Any exposure to caffeine during pregnancy was associated with an increased risk of the child being overweight by the age of three to five years. The risk remained till the child was eight and was highest when the mothers took over three cups a day during pregnancy.

For this study the mothers were asked to report the foods and drinks they consumed 22 weeks into their pregnancy from a huge list of foods and beverages questionnaire called the Food Frequency Questionnaire that contained 255 items. Caffeine is not only obtained from coffee but also from black tea, chocolate and chocolate milk, fizzy drinks, desserts, sweets, cakes and sandwich spreads. A cup of tea contains 75 mg, a cup of filter coffee 140mg, a can of cola 40mg and a can of energy drink up to 160mg of caffeine. Low caffeine intake was found in 46 percent of the participating mothers while 44 percent showed average intake and 7.13 percent showed high intake of caffeine during pregnancy.

A significant number of mothers – 3.21 percent - showed very high intake of caffeine (around 300mg per day) during pregnancy. Once the baby is born, the child was followed up until they were 8 years old and their weight and height was measured at 11 points of health checkups. The team noted however that the mothers who consumed higher amounts of caffeine were more likely to be older, had more than one child, obese themselves, less educated, smokers and consuming excess daily calories. These factors also could be playing a role in childhood obesity seen in their babies.

She explained that earlier animal studies have shown that caffeine in babies and infants can modulate the metabolism in various ways and increase the risk of obesity and heart disease. Caffeine can alter the chemicals that play an important role in metabolism and overall growth. Leptin is a hormone that regulates appetite. Caffeine in pregnant mothers allows leptin to pass through the placenta into the babies.

One of the biggest strengths of this study according to the authors, is its large population. This means that the results can be relied upon. Authors concluded that “Any caffeine consumption during pregnancy is associated with a higher risk of excess infant growth and of childhood overweight, mainly at preschool ages. Maternal caffeine intake may modify the overall weight growth trajectory of the child from birth to 8 years.”