By Anna Carey

It's hard to know what to believe when you're expecting a baby. Everyone has an opinion on what's right and wrong for you and your bump, but a lot of their advice might not be reliable.

There are a lot of myths about pregnancy - a study recently published in the British Journal of Psychiatry revealed that, contrary to popular belief, women don't actually experience "baby brain" - forgetfulness and other cognitive problems - when pregnant.

"Women may have memory lapses, and change their focus to children and upcoming birth," said the study's author, Dr Helen Christensen, a researcher at The Australian National University in Canberra. "This does not mean they have lost their capacities."

So what other old wives' tales could do with a bit of debunking? It's time to examine 10 of the most persistent pregnancy myths...

Exercising while pregnant is dangerous

There's nothing wrong with exercising when you're pregnant. "If you've been exercising a lot before your pregnancy, you can basically continue - with a few qualifications," says Niamh Healy of the Irish Childbirth Trust.

Exercise should be evaluated by what's known as the "talk test". Whatever exercise you're doing, you should be able to do it while carrying on a conversation. If you're too out of breath to talk, says Healy, "reduce the intensity".

It's also safe to start a new exercise regimen - as long as you use your common sense. "Don't go abseiling or train for a marathon," says Healy. She also points out that as pregnancy progresses, women should be aware of their changing centre of gravity when playing any sport that involves twisting and turning, as they may find it hard to keep their balance.

How you carry your baby bump will predict the child's gender

How many times have you heard someone say that a woman who is "carrying high" is going to have a boy? In reality, there is no direct correlation between a woman's bump and her baby's gender.

In fact, the height of a bump has more to do with the mother's muscle tone - which is why first babies are often carried higher, as the woman's muscles are likely to be tighter. So why does this myth persist? Well, as Niamh Healy points out, "You've got a 50 percent chance of being right".

Morning sickness means your bump is healthy

Many women who've spent the first months of pregnancy hanging over a toilet bowl will have been reassured by the news that this is a good sign. And it is.

"Morning sickness is your body telling you that pregnancy hormones have kicked in and things are going well," says Healy.

But she stresses that the absence of morning sickness isn't a bad thing at all - some women just have easier pregnancies.

If you use the right creams, you won't get stretch marks

While moisturising can help ease itching and keep your skin soft, no cream can guarantee that a woman won't get stretch marks.

According to Professor Alexa Boer Kimball, a dermatologist at Harvard University medical school who has studied the effects of various creams aimed at pregnant women, genetics plays a factor, as does the speed with which a woman gains weight over her pregnancy. But, she stresses, oils or moisturisers have nothing to do with it.

Dying your hair can harm your foetus

Some claim that the chemicals in hair dyes can affect a foetus - this belief was fuelled by an old study which showed that hairdressers who were exposed to high levels of chemical dyes experienced a slightly higher than usual number of miscarriages. However, the vast majority of modern dyes should be perfectly safe.

"Hair highlights are applied to the hair shaft, not the scalp where chemicals can be absorbed, so highlights are considered safe during pregnancy," says midwife Maylyn Bonds. "With other hair dyes, there is not a 100 percent guarantee that no chemicals will be absorbed through the skin, but the amounts are so tiny that the risk is thought to be minimal."

Spicy food can induce labour

There might be a grain of truth in this one, but nothing has been scientifically proven.

Some people believe that spicy food can encourage what Healy refers to as "a digestive clear-out" which could create some extra space in the abdomen, allowing the baby's head to move slightly towards the cervix.

"You might as well give it a go - if you like curry," says Healy. "It won't do you any harm."

When giving birth, never question any official orders

Many women feel they have to do whatever they're told when they arrive at a hospital, leading in some cases to a scary feeling of losing control. Healy stresses that it's always okay for a mother-to-be to ask questions and make suggestions.

"The first question should always be: 'Is this an emergency or do we have time to talk?' " she says.

"Safety is paramount, so if something needs to be done immediately, don't argue."

But if mother and baby are in no apparent danger, she suggests asking the team to explain the rationale for the planned birth procedure, going over any risks or possible consequences of various approaches, and discussing your options - which can include just doing nothing for a while.

Sleeping on your back is bad for the baby

It's true that if you lie on your back in the later stages of pregnancy, the weight of the uterus can put pressure on the blood vessels going to the lower part of your body and to the placenta.

So some women do find that they feel dizzy after lying on their back for a while. But many will feel fine.

"Listen to your body and heed its messages," says Healy. "If you feel dizzy after being on your back, then don't do it. The recommendation is that women sleep on their side, but there's no point in getting anxious if you can't sleep that way."

Having sex can damage your unborn baby

There's no danger of hurting a foetus through penetrative sex. But if the baby is ready to arrive anyway, sex can help it on its way.

"Theoretically, it can help soften the cervix a little and allow the body to go into labour," says Healy. "For many women, it's a favourite natural method of induction."

And don't worry if the foetus isn't full term - this triggering happens only when a baby is due.

Some doctors do warn against sex in the third trimester for women with a history of premature labour or vaginal bleeding, but the vast majority of women should be able to have sex whenever they like - as long as they're comfortable.

Breastfeeding will always make you lose your baby-weight faster

Some women credit breastfeeding with their ability to get back in their skinny jeans just a few weeks after giving birth.

But while breastfeeding is an excellent idea for both mother and baby, it's not an automatic way of losing those pesky pregnancy kilos.

"It all depends on how much weight you've put on," says Healy. It also depends on what you're eating now. Breastfeeding usually uses up about 300 to 400 calories a day.

However, breastfeeding can also stimulate the production of the hormone proclactin, which can stimulate the appetite.

So, as ever, if you're taking in more calories than you're burning, you won't lose any weight - no matter how well-fed your baby is. - Irish Independent