Smoking 'risks chance of lesbian baby'

Women who smoke or lead a stressful life during their pregnancy can influence their child's sexuality and IQ, a neuroscientist has claimed.

A pregnant woman's lifestyle is believed to have an impact on the development of babies - with drinking, taking drugs and living in an area with a lot of pollution affecting children in later life.

Dick Swaab, professor of neurobiology at Amsterdam University, suggests drinking and taking drugs can lower a child's IQ, while taking synthetic hormones and smoking can increase the likelihood of girls being lesbians or bisexual.

Having more older brothers is also thought to increase the chance that boys will be gay, possibly because of the development of the mother's immune system to have stronger responses to male hormones with each son born.

"Pre-birth exposure to both nicotine and amphetamines increases the chance of lesbian daughters," Swaab told the UK's Sunday Times.

"Pregnant women suffering from stress are also more likely to have homosexual children of both genders because their raised level of the stress hormone cortisol affects the production of foetal sex hormones."

He said the brain in foetuses begins to develop at two weeks, with anything that introduces toxins into the body having an impact on this development.

Studies show women who took synthetic oestrogen between 1939 and 1960 to reduce the chance of miscarriage had a greater chance of bisexuality and lesbianism in their daughters.

Swaab said: "In women who drink a lot, cells that were meant to migrate across the foetal brain can end up leaving the brain altogether."

Living in an area of high pollution is linked to an increased risk of autism.

Swaab said lifestyle factors are just one influence, with genetics playing the most important role, but he said the research proves that the development of the brain during pregnancy is directly linked to adult lifestyles.