Smoking while pregnant found to increase risk of ‘cross eyes’ and reduced fertility in baby

April 19, 2010 by Shawn Douglas
Filed under: News, Pregnancy

Smoking while pregnant increases the chance of eye problems and low fertility counts in babies, according to two separate scientific studies.

Research on how women who smoke while pregnant affect the development of their child has been going on for decades. Recently published studies in the American Journal of Epidemiology and Philosophical Transactions of the Royal Society B add to the mountain of evidence that smoking while pregnant is detrimental to the developing baby.

Dr. Tobias Torp-Pedersen and his team of researchers at the Statens Serum Institut in Copenhagen, Denmark found that smoking while pregnant increased the risk of strabismus, a condition in which the eyes are unable to align evenly.

Dr. Torp-Pedersen said that little is known about the origin of the condition, but theorized that chemical disturbance could yield degeneration in the eye muscles and nerves. “Nicotine and other substances in tobacco, alcohol and caffeine all affect the brain in some way,” said Dr. Torp-Pedersen. “Minor disturbances to the developing brain could plausibly lead to strabismus.”

The team reviewed 1,300 cases of strabismus in children born between 1996 and 2003 using data from the Danish National Birth Cohort. Included in the data were interviews with the children’s mothers during and after pregnancy.

“We were able to show that each extra cigarette smoked per day during pregnancy exerted a 5 percent increase in strabismus risk, which is a new finding,” Torp-Pedersen told Reuters Health.

In a second, unrelated study, Professor Richard Sharpe of the Queen’s Medical Research Institute in Edinburgh performed a comprehensive review of numerous medical studies on the effects chemicals and obesity have on the sperm production of male babies.

Sharpe found that a mother’s smoking habits while pregnant had much more of an impact on a male’s sperm production than cigarette exposure outside the womb, later in life. He theorizes that the risk is greater in the womb because toxins in the blood stream reduces the number of sertoli cells, highly specialised cells needed to support the growth of young sperm all the way through to a man’s adult life.

Sharpe was skeptical, however, about how much any individual chemical in the womb contributes to poor sperm development. He did suggest that large “cocktails” of a variety of chemicals may have a combined effect, but more research was required he said.

“The high prevalence of low sperm counts in young men across Europe today is a cause for concern, especially when considered together with the trend for ever-later age for first pregnancy in the female partner,” said Sharpe in his review.

“As this review has shown, evidence for widespread or major effects of individual lifestyle or environmental factors on spermatogenesis in adulthood is largely lacking, whereas there is growing evidence that prenatal exposures of males (due to maternal lifestyle or exposure) can have a major impact on capacity to produce sperm in adulthood.”

Dr. Allan Pacey, a Sheffield University expert in male fertility, told the Daily Mail: “This review reminds us that the sperm production capacity of men is probably established quite early in life and perhaps even before they are born. This highlights the importance of women having healthy pregnancies and not exposing their baby to harmful chemicals, such as cigarette smoke.”

Dr. Torp-Pedersen’s research appears in the March issue of American Journal of Epidemiology, while Professor Sharpe’s work appears in the upcoming May 27 issue of Philosophical Transactions of the Royal Society B.