Knowing your limits
The fact that heavy drinking is harmful during pregnancy is widely known but there is still some confusion as to whether any alcohol at all is a good idea when you're expecting. Arlene Harris reports
Published 24/02/2016 | 02:30
There was a time when it wasn't unusual to see a pregnant woman with a drink in her hand - and in fact, expectant women were advised that a certain alcoholic beverage was 'good for you' and your unborn baby.
But times changed as did medical advice, which urged women to stay away from alcohol for the duration of their pregnancy. Then came the conflicting advice stating that it was fine to have a glass or two of wine, particularly during the last trimester.
Now, the latest research from the Centers for Disease Control and Prevention (CDC) in the US is advising women not only to cut out alcohol completely when they become pregnant, but to stop drinking as soon as they start trying for a baby.
However, despite the conflicting advice, it seems that most women continue to drink a certain amount of alcohol both before and during pregnancy.
"Up to 80pc of women consume some level during pregnancy, irrespective of age and educational status," says Professor Louise Kenny.
She and her colleagues at UCC have found that heavy consumption of alcohol is detrimental to the unborn baby but results of the effect of low-level drinking is still uncertain. "Studies of heavy alcohol exposure (typically defined as more than seven drinks per week or an average of one drink per day) during pregnancy have illustrated substantial effects on growth and cognitive outcomes from birth throughout childhood," she says.
"But, in relation to light to moderate drinking (less than seven drinks per week) during pregnancy, numerous studies have indicated no effect of low levels of consumption for birthweight or small for gestational age (SGA), while others have found a beneficial or harmful effect."
So while there is no clear evidence regarding the effect of low-level alcohol consumption during pregnancy, the consultant obstetrician says international guidelines still advise women to steer clear of alcohol during for the duration of their gestation.
"Worldwide, the majority of clinical and government guidelines advocate for pregnant women to abstain from alcohol consumption during pregnancy due to potential adverse effects but also lack of evidence on a known safe level of alcohol consumption for pregnant women," she says.
"Over the last decade, guidelines in a number of countries have moved from deriving information on safe lower levels of alcohol consumption during pregnancy to advising complete abstinence due to lack of robust evidence.
"The current guidelines aim to be precautionary by protecting women (either planning a pregnancy or already pregnant) from any yet unknown potential risks. And also by not causing unnecessary worry and anxiety in women inadvertently exposed to small amounts of alcohol in early pregnancy, since the overall risks, although not yet well quantified, are likely to be low."
Midwife and author of eBook Bump to Birth to Baby Margaret Hanahoe also says while advice has been confusing over the years, it is best to avoid alcohol altogether for the duration of your pregnancy.
"Pregnant women have received conflicting advice over the years about drinking alcohol during pregnancy and this confusion was caused because the exact level of alcohol at which harm starts to be caused to the unborn child has not been identified," she says. "It is known that the risk of damage increases in line with how much you drink so binge drinking is more harmful than drinking small amounts of alcohol.
"Therefore it is advised to avoid alcohol completely because, as there is no known 'safe' level of alcohol during pregnancy, the safest thing to do is not drink at all as what is very clear is that there are no benefits for the unborn child from exposure to alcohol."
The experienced midwife says even the smallest amount of alcohol can have an adverse effect on an unborn baby.
"During pregnancy alcohol passes from the mother's bloodstream through the placenta and into the baby's bloodstream, where it can affect its development," she says.
"In 2012 a study said that women who drink as little as one small glass of wine a week while pregnant could risk reducing their child's IQ. Some children appear to have genes which make them vulnerable to alcohol and even being exposed to relatively small amounts of alcohol before birth could have a significant impact on intelligence at age eight.
"Drinking heavily while pregnant can also increase the chances of complications during pregnancy and childbirth as well as increasing the risk of premature delivery, miscarriage and stillbirth. It also carries a risk of Foetal Alcohol Syndrome (FAS) and Foetal Alcohol Spectrum Disorder (FASD)."
Children born with FAS have been exposed to high levels of alcohol and can experience problems with their growth, facial defects, as well as lifelong problems. Symptoms include:
• Poor growth while the baby is in the womb and after birth
• Decreased muscle tone and poor coordination
• Delayed development and problems in three or more major areas: thinking, speech, movement, or social skills
• Heart defects
• Problems with the face, including narrow and small eyes with a small head, small upper jaw, smooth groove in upper lip, and smooth and thin upper lip.
So it appears that while there is no concrete evidence outlining exactly what the effects are of occasional drinking during pregnancy, Joe Barry, professor of Population Health Medicine at TCD would also urge pregnant women to steer clear.
"The best advice is that there is no known safe level of alcohol during pregnancy and consequently it is advised to avoid alcohol when pregnant or if trying to become pregnant," he says.
"The exact level of alcohol at which harm starts to be caused has not been established but the risk increases in line with the amount taken.
"Alcohol is a toxic substance. Drinking during pregnancy carries a risk of Foetal Alcohol Syndrome (FAS) or Foetal Alcohol Spectrum Disorder (FASD).
"Children born with FAS can experience problems with their growth, facial defects, as well as lifelong learning and behavioural problems. Children with FASD, more common but less severe than FAS, can have issues such as sight and hearing difficulties, problems paying attention and following simple directions, as well as other learning difficulties.
"Ultimately, there are no health benefits of drinking alcohol during pregnancy."
Cutting out alcohol before you conceive
Even before you get pregnant, but you’re trying for a baby, should you think about giving up alcohol? Scientific evidence as to how light and moderate drinking affects a woman’s fertility isn’t clear but studies have shown that there is a link.
A 2009 study at Harvard University of couples undergoing IVF treatment found that women who drank more than six units of alcohol a week were 18pc less likely to conceive.
Another Danish study of 430 couples trying to conceive for the first time found that women, even with a relatively moderate intake of five units of alcohol a week, had reduced chances of getting pregnant.
Last year the Royal College of Obstetricians and Gynaecologists in the UK advised that women wishing to get pregnant should avoid alcohol completely and that either partner drinking heavily can make it more difficult to conceive.
So while there is no overwhelming evidence that cutting out alcohol completely will boost your fertility, it may be a decision you choose to make alongside other lifestyle choices which may help fertility including:
* Giving up smoking: Women smokers are 1.5 times more likely than non-smokers to take longer than a year to get pregnant.
* Reducing caffeine: Although there is no clear evidence that caffeine affects fertility, some studies have suggested that high levels of consumption can make it harder to conceive.
* Maintaining a healthy weight: Obesity can cause hormonal imbalances and problems with ovulation.