Judging from what you hear in pregnancy you’d think those old wives spent the whole day thinking up new ways to worry you. Is there truth in any of those pregnancy myths and rumours?

Truth or scare?

There’s a whole range of rumours and myths surrounding pregnancy, many of them dating from the days when we didn’t have technology to set our minds at rest and tell us what was going on in there. So should you pay attention to any of them?

Bump shape = boy or girl

Once your bump starts to show, not a week will pass without someone eyeing it knowingly and announcing that you’re carrying low so it must be a boy (or high, for a girl). In fact, the way you carry your baby depends on your muscle tone, whether it’s your first pregnancy, the position your baby is lying in and his age and size. It has nothing to do with whether it’s packing that extra inch or so between its legs.

A fast heartbeat means it’s a girl

Even obstetricians and midwives have been known to say this but there’s no evidence to back it up and in any case your baby’s heart rate is likely to vary anyway depending on how active he is when your obstetrician or midwife monitors it.

Heartburn means hair!

Heartburn is very common in pregnancy – chalk it up to pregnancy hormones loosening the muscles of your oesophagus. But no, it doesn’t mean your baby will be born with a full head of hair!

Sickness is worse with girls

Like the other gender-related pregnancy myths, this one is generally considered untrue… although there is some evidence that women who are hospitalised for severe sickness in pregnancy are more likely to go on to have girls.

You should sleep on your side

This myth springs from evidence that blood flow through the placenta can be reduced if you lie on your back during labour. There may be circumstances where your obstetrician or midwife recommends that you rest on your left side as a safeguard – for example, if you’re high risk – but as far as sleeping is concerned you can go ahead and lie on your back.

Raise your arms to untangle the cord

Nothing you do has any bearing on your baby’s umbilical cord. Babies are born with it tangled, knotted, and caught around their limbs and even their necks. How tangled he gets in it is due to your baby’s activity in the uterus when he is very small.

Having sex will hurt your baby

You may be advised to avoid sex if you’re high risk (for example, if you’ve suffered frequent miscarriages or there is a danger of early labour) but in the main, sex is fine right up until the day you have your baby (though it may get a tad uncomfortable once you’re the size of a house!). It’s even said to be one way to kickstart labour naturally. Similarly, your unborn baby won’t be able to ‘sense’ your partner’s penis, so there's no need for dad to feel squeamish.

Pregnancy ruins your teeth

There was some basis for this back in the day when nutritional deficiencies meant there was a risk of entering your childbearing years without an adequate store of calcium to support an unborn baby’s needs. Your obstetrician or midwife may recommend you take a calcium supplement and good food sources of the mineral include dairy products, leafy green veg (kale, broccoli, spinach), canned sardines with the bones, fortified tofu and fruit juices.

It’s not safe to exercise if you’re pregnant

As long as you’re used to it, exercise is fine: in fact it’ll help boost your energy and relieve stress. But keep it gentle (pregnancy hormones loosen muscles and ligaments, which can make them more vulnerable to injury) and avoid high-impact exercise, such as running or step. Walking and swimming are ideal; alternately try an antenatal yoga class. If you’re taking part in any other exercise classes, make sure your fitness instructor knows you’re pregnant; keep your obstetrician or midwife in the loop too.

Morning sickness starves your baby

Morning sickness is one of the most common pregnancy symptoms, and is believed to be caused by pregnancy hormones. It’s easy to panic if you’re throwing up every morning and you don’t seem to be gaining weight but try not to worry – you won’t really start to gain weight until later in your pregnancy. As long as you were healthy before you became pregnant your baby will be more than adequately nourished. However it is possible that severe pregnancy sickness (hyperemesis gravidarum) can compromise your baby so tell your obstetrician or midwife if you aren’t able to keep any liquids or foods down.

You can’t take medication

If you have a chronic health problem that requires daily medication (for example, high blood pressure or epilepsy), tell your doctor you’re planning a family before you start trying, or the moment you find out you’re expecting if it’s a surprise pregnancy. It is possible your dose may have to be modified or that an alternative drug might be better for your baby while you’re pregnant. As far as aches and pains go, consult your doctor as to what’s safe to take – as a guide, ibuprofen should be avoided but paracetamol is generally considered safe.

You shouldn’t fly

Flying is safe in pregnancy, although if you work in the airline industry you may need to modify your schedule since there is risk from radiation exposure. Take care to get up and move around on long flights to avoid blood clots (and if you’re planning one last holiday before the baby, check airline policy – it may not permit long-haul journeys after a certain date in your pregnancy).

Now you can eat for two!

Nope – pregnancy isn’t a licence to eat every sticky bun in the borough. In early pregnancy, your calorific needs are pretty much the same as they are in your non-pregnant state. It’s only in late pregnancy, when your baby is growing bigger and laying down fat in readiness for birth, that you need to eat more – and even then it’s only around 300 calories extra a day.

Computers can harm your baby

There’s no evidence that it is unsafe to use a computer when you’re pregnant; mobile phones are safe too. There is some evidence that microwaves might pose a risk but only if it’s an older model and there is a leak. If you use an older one regularly, keep your distance as a precaution.

Coffee is bad for your baby

Caffeine increases your heart rate and blood pressure, and can cross the placenta. Studies also indicate that consuming more than three cups of coffee a day increases the risk of miscarriage, early labour and low birthweight. Keep coffee consumption to a bare minimum – and bear in mind that coffee is not the only source of caffeine: it’s also present in tea, cola, chocolate and some OTC painkillers.

Salon treatments aren’t safe

There is some evidence that chemicals used in hair dye can enter your bloodstream though experts say exposure levels would have to be extremely high to put your baby at risk. Your obstetrician or midwife may advise you to avoid colouring or perming your hair until you pass the first trimester, since your baby will be fully-formed by then. Highlights should be fine, though, though, as very little of the colourant comes into contact with your scalp.

You can still wax your bikini line (but keep in mind that some women develop varicose veins in the vulval area during pregnancy – avoid waxing if this is the case) and get your nails done, though you should make sure the salon is well-ventilated and ask your manicurist to use natural, biodegradable products instead of strong chemicals. If you’re used to faking it where your nails are concerned you may not have to in pregnancy – one of its positive side effects is that nails grow faster! Tanning beds are a big no-no, as pregnancy hormones make you more susceptible to burning.

If you’re a fan of massage, avoid it in the first trimester as there’s some evidence linking it, and some essential oils used in aromatherapy massage, to miscarriage. Reflexology massage has been linked with pre-term labour so avoid it (save it for kickstarting your labour if you go past your due date!). Otherwise, go for it: prenatal massage is a great soothing solution to pregnancy stress. Tell your therapist that you’re pregnant if your bump isn’t showing yet.

It’s time to kick out the cat!

Cats can carry toxoplasmosis, which can harm an unborn baby. If you have a cat, your doctor can test you to check if you have it or have been infected in the past. You can also get your vet to test your cat for the parasite, and play it safe by wearing gloves to empty and clean its litter tray (or by asking someone to do the job for you). But it’s perfectly fine to let Fluffy sit on your lap and to stroke him. Toxoplasmosis can also be transmitted via garden soil that may have been contaminated by cat faeces, and by undercooked meat.