Coffee during pregnancy can reduce the child’s height by a centimeter

Drinking just half a cup of coffee a day during pregnancy can reduce the height of the child by almost one centimeter, according to an official study.

Juveniles born to women who consumed 50 mg of caffeine each day were 2 cm (0.8 inches) shorter than their peers by age eight.

The finding remained even after adjusting for other factors that affect a child’s height — including their mother’s age, smoking status and income.

Researchers say the results – based on an analysis of 2,500 boys and girls across the US – show expectant mothers should abstain from coffee altogether.

Right now US guidelines recommend that pregnant women limit their daily intake to around 200 mg. An average 8 oz cup of coffee contains about 100 mg of caffeine.

Caffeine is thought to constrict blood vessels in the uterus and placenta, which can reduce blood flow to the fetus and slow growth.

The study is the first of its kind to use blood tests to measure caffeine intake in pregnant women instead of surveys, which are less reliable.

The results were published in the journal Jama Network Open.

Researchers at the National Institute of Child Health and Human Development in Maryland followed children born between 2009 and 2013 until they were eight years old.

Mother-child pairs recruited for the study were divided into four groups based on the amount of caffeine the mother consumed during pregnancy.

Plasma samples were collected from each mother during the first and third trimesters to estimate how much caffeine the mother was drinking.

Those with 25.4 nanograms per milliliter (ng/mL) or less of caffeine detected in plasma samples were placed in quartile one.

Mothers in the highest quartile had levels of 575.3 ng/mL or higher.

The researchers note that it would only take about 50 mg of caffeine per day to raise a person from the first to the fourth quartile.

After following the children for more than eight years, the researchers found a clear correlation between caffeine consumption and height.

The difference became apparent when the child was about 20 months old and only increased as the child got older.

By age seven, the difference in height between those who consumed the least caffeine and those who drank the most was an average of 1.5 cm.

By the eighth year, the difference was 2.3.

This was all after controlling for race and mother’s education, factors that can also influence child height at an early age.

No similar correlation was found when it came to body mass index, indicating that caffeine exposure in utero has no effect on weight during life.

Writing in the paper, the team said: ‘Children of women with low measured caffeine … during pregnancy were shorter than children of women who did not consume caffeine during pregnancy, with height differences widening in the historical cohort by age eight.

‘These findings suggest that low amounts of daily caffeine consumption in mothers are associated with lower growth in their offspring that remain in childhood.’

There is limited data on why exposure to caffeine in utero and early in life may inhibit growth.

IN Study from 2021, Researchers have found that caffeine causes blood vessels in the uterus and placenta to constrict, reducing blood flow to the fetus.

This led to the babies having a lower birth weight, although they did not determine the long-term effects this might have on their development.