Image caption If pregnant women choose to drink, they are advised not to consume more than two units a week

Light drinking during pregnancy does not harm child behavioural or mental development, reports the journal BJOG.

The abilities of 10,534 UK seven-year-olds, whose mothers had either abstained from alcohol or drank lightly while pregnant, were analysed.

Little difference was found between the two groups - supporting UK government guidelines.

These advise pregnant women to abstain from alcohol, and if they drink, to consume no more than two units a week.

Prof Yvonne Kelly, co-author of the study in An International Journal of Obstetrics and Gynaecology (BJOG) said: "We know heavy drinking during pregnancy has a very deleterious effect, but it is very unlikely that drinking small amounts will have an impact.

"It doesn't seem biologically plausible that small amounts of alcohol would affect development either way. The environment children grow up in is massively more important.

"While we have followed these children for the first seven years of their lives, further research is needed to detect whether any adverse effects from low levels of alcohol consumption in pregnancy emerge later in childhood."

Light drinking was classed as consuming up to two units of alcohol per week. A unit is half a pint of lager or a single measure of spirits.

'Safest option to abstain'

John Thorp, from the journal in which the paper was published said: "These findings, that drinking not more than one or two units of alcohol per week during pregnancy is not linked to developmental problems in early-mid childhood, are consistent with current UK Department of Health guidelines.

Government Alcohol Advice for Pregnant Women If women want to avoid all possible risks, they should not drink alcohol during pregnancy because the evidence is limited

If you choose to drink, limit consumption to no more than 1-2 units of alcohol once or twice a week

Avoid getting drunk or binge drinking

"However, it remains unclear as to what level of alcohol consumption may have adverse outcomes so this should not alter current advice and if women are worried about consumption levels the safest option would be to abstain from drinking during pregnancy."

The study collected data from the Millennium Cohort Study, a national study of infants born in the UK between 2000-2002. When these children were nine months old their mothers were asked whether they had drunk alcohol during pregnancy.

Around 57% said they abstained during pregnancy and 23% were light drinkers.

When the children reached the age of seven, their parents and school teachers were asked to assess their social and emotional behaviour - including hyperactivity and attention problems. Their maths, reading and spatial skills were also tested.

The study findings also hinted that boys born to light drinkers had fewer behavioural problems and better reading and spatial skills than those born to mothers who did not drink during pregnancy,

Prof Kelly urges people not to read too much into this: "Where there are differences the differences are very small."

Past studies have also suggested this - although it has been argued the differences may have arisen as light drinkers may come from a higher income or more educated background than abstainers.

'Reassuring'

Patrick O'Brien, a spokesman for the Royal College of Obstetricians and Gynaecologists (RCOG) and a consultant obstetrician said the research was very well designed.

"This is a very good paper and controlled for socio-economic and cultural confounding factors as well as possible. Although it didn't control for all of them - like IQ.

"No-one is suggesting drinking alcohol while pregnant is beneficial."

Linda Geddes, author of the pregnancy book Bumpology thinks this new research is helpful.

She said: "A lot of women are conflicted - they know their mothers had a little to drink while pregnant with them, and they see friends and relatives drinking - they may think the occasional drink is OK, but they also know the absolute safest thing to do is not to drink at all as the evidence is limited and they want to do the best by their babies.

"So this research is very reassuring for pregnant women - it is probably OK to have a glass or two."

The Department of Health spokesperson said:

"The Chief Medical Officer is overseeing a review of alcohol guidelines, This will include reviewing any new evidence on alcohol and pregnancy. To encourage mothers-to-be to cut out risky health behaviours like drinking alcohol we recently relaunched Start4Life."