Wednesday, March 24, 2010

'Baby brain' and 12 other pregnancy myths

Pregnancy may bring a rush of euphoric emotions for many women, but it can also mean nine months of paranoia and panic. We are fed so much information that the path from conception to labour can be fraught with confusion. Once that bump appears, everyone has an opinion on everything from the gender of your child to how you should live your life while carrying him or her.

And who knows what to believe? Last week, for instance, the long-held belief being that pregnancy triggers memory lapses dubbed “baby-brain” syndrome was debunked by a report in the British Journal of Psychiatry. According to a study by the Australian National University in Canberra, neither pregnancy nor motherhood damaged brain power, so being forgetful can no longer be blamed on the baby.

Then came the revelation from the supermodel Gisele Bündchen that she had sailed through labour, giving birth to her son in the bathtub at her Boston penthouse. “It wasn’t painful, not even a little bit,” said the 29-year-old Brazilian, right. “The whole time, my head was so focused — every contraction, the baby is closer, the baby is closer. ” So should all women be rushing to use birthing pools? Not necessarily. No evidence confirms that childbirth is less painful in water. “Birthing pools work for some,” says Maylyn Bonds, a midwife for Tommy’s, a charity that funds research into pregnancy problems. “They don’t help others.”

Many more myths can be exploded. Here we review the evidence that scuppers 12 old wives’ tales:

Don’t dye your hair

For many women, the prospect of nine months without attention to their roots and highlights is almost too much to bear. Fears about hair dyes stem from small studies that indicate that some chemicals penetrate the scalp. Hair colourists exposed to dye on a daily basis have been shown to be at a slightly higher risk of miscarriage. However, there is no direct evidence that hair dyes are harmful to the foetus, and many of the studies were based on unfeasibly high levels of chemicals.

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

Having sex during pregnancy can harm the baby

According to Bonds, a doctor might caution against sex in the third trimester for a minority of women who have a history of premature labour, vaginal bleeding or placenta previa (when the placenta covers the cervix) in case it triggers early labour, but for most women the message is that sex won’t harm the foetus.

Dr Sarah Jarvis, a GP and author of Pregnancy for Dummies, says that there is some truth in the belief that, in the later stages of pregnancy, sex prepares the body for labour. “Love-making stimulates the body to produce the hormone oxytocin, which can help your cervix ripen in readiness for labour,” she says.

“The partner’s semen also contains hormones called prostaglandins, which can cause contractions.”

Morning sickness is a sign that a foetus is healthy

Morning sickness has nothing to do with the health (or gender) of a foetus. The increased nausea and vomiting are associated with higher levels of hormones produced by healthy placental tissue combined with low blood-sugar levels, says Bonds. One theory suggests that morning sickness — which can occur at any time of the day — may help women to avoid foods that could harm a foetus.

A few studies have linked morning sickness to lower rates of miscarriage, however many other studies have failed to find a link. Bonds says: “It is just another symptom of pregnancy and doesn’t indicate whether a baby is thriving.”

If your bump is high, you are carrying a girl; if it’s low, it’s a boy. But is there any truth in the myth that you can tell the sex by the shape of your bump? Bonds says that, other than an ultrasound scan, there is no way to determine a baby’s gender.

How you carry your bump can predict gender

How a bump is carried is as much to do with the mother’s body shape and muscle tone. With first babies, the muscles and ligaments tend to be tighter so babies are carried higher. But a bump’s position is also determined by the baby’s presentation (whether it is breech or transverse), and its gestational age and weight. “Gender has nothing to do with any of it,” Bonds says.

Sleeping on your back can harm the baby

In the 1960s and 1970s research showed that blood flow can be compromised in women made to give birth lying flat on their backs because a major vessel, the vena cava, underneath the uterus becomes compressed. But those findings don’t necessarily mean it is dangerous to sleep on your back while pregnant.

Dr Philip Owen, a consultant obstetrician and gynaecologist at North Glasgow University NHS Trust, says that the best resting position when pregnant is to lie on your side with your knees bent, which “makes the heart’s job easier because it stops the weight of the baby applying pressure to your large veins”.

However, in a normal, healthy pregnancy, experts say that a baby can generally accommodate any sleeping position that the mother adopts to ensure she gets a restful night.

Stretch marks are avoidable if you slather on creams

Diligently applying expensive creams and potions from day one of pregnancy must surely pay off. But according to research by Professor Alexa Boer Kimball, a dermatologist at Harvard University medical school, there’s no proof that any of the creams and oils that claim to prevent stretch marks actually work. The most they can achieve is a reduction of itching caused by dry skin during pregnancy.

Stretch marks develop because of changes in the elastic supportive tissue that lies just beneath the skin. No one really knows why about half of pregnant women get them, and the rest don’t.

Kimball says that genetics play a role but that how much and how quickly your skin has to expand during your pregnancy is also a factor. “The skin is very elastic,” she says. “But weight gain in pregnancy can be pretty dramatic, and sometimes it’s more than the skin can handle.”

Don’t take up exercise when you are pregnant

Thirty years ago the advice to pregnant women was that a gentle stroll was their physical limit and they should cover no more than a mile a day. Now researchers have confirmed that more exercise is not only safe but beneficial, even for women who have never been active before.

In a study of more than 150,000 pregnant women by exercise physiologists at the University of St Louis, most did not meet even the minimum requirement of daily activity — 30 minutes of moderate exercise a day for healthy expectant mothers. Many wrongly believed that exercise can damage an unborn child by starving it of blood and oxygen. In fact, said the researchers, a woman’s heart pumps more blood than normal to ensure the foetus is not deprived when she works out.

“Women who worked out before should continue in the same vein provided their pregnancy is healthy, avoiding only contact sports, scuba diving or other activities that might cause abdominal distress,” says Louise Sutton, of the Carnegie Centre for Sports Performance at Leeds Metropolitan University. “But there is no excuse not to start exercising in pregnancy — the first step should be moderate, non-weightbearing activities, such as brisk walking, swimming or cycling.”

Don’t fly in the first trimester

The consensus among experts is that air travel is safe for most women. Although radiation exposure does increase at high altitudes, only frequent fliers approach anything near the upper safety limits.

“Flying is considered perfectly safe for pregnant women,” says Bonds. “Only women who have had a previous history of miscarriage, premature birth, low placenta or bleeding in pregnancy will be advised to avoid it by their doctor.”

However, she adds, because pregnancy and sitting down for long periods on a plane increase the risk of blood clots, it is particularly important to get up and walk around to avoid deep vein thrombosis.

Don’t sit in front of a computer

There is no scientific evidence to suggest that a women needs to limit her exposure to a computer screen. While tiny amounts of low-frequency electromagnetic radiation are emitted from the back of computers, none comes from the front.

Obstetricians at Montefiore Medical school in New York found that radiation is minuscule, particularly now that LCD screens are used.

A bigger risk, says Sammy Margo, a spokesperson for the Chartered Society of Physiotherapy, is the painful wrist complaint, carpal tunnel syndrome, caused by prolonged use of a keyboard and bad posture, especially with ligaments becoming more lax as pregnancy progresses.

Curry and raspberry leaf tea will induce labour

Nearly a fifth of women questioned in a study for Tommy’s last year thought that wolfing down a curry would trigger labour, and 38 per cent thought raspberry leaf tea was the answer for a quick delivery.

Raspberry leaf tea has been used as a uterine tonic by Native Americans for thousands of years and is thought to help to tone the uterus and to trigger contractions.Spice is thought to increase production of prostaglandin. This hormone helps to contract the smooth muscles of the body and is known to play a role in inducing labour. But, says Sharon Broad, a Tommy’s midwife, there is no evidence to support the view that either raspberry leaf tea or curry induce labour. It’s all anecdotal.

Natural birth is better than a Caesarean section

One in four babies in the UK is delivered by Caesarean section according to the latest NHS statistics, double the number 20 years ago. Emergency Caesarean sections, for problems such as foetal distress, prolapsed umbilical cord or failure to progress in labour, still account for the lion’s share, as both midwifery and medical staff are increasingly likely to err on the side of caution if either mother or baby seems to be getting into trouble. But are mothers who have Caesarean deliveries selling themselves and their babies short?

“Most mothers would probably like to have a natural vaginal birth but if this is not possible, Caesarean should not be viewed as a failure,” says Bonds. “The recovery after a vaginal birth is quicker and easier than for mothers who have had Caesareans, but the best way is the safest way for the baby and mother — whichever route that might be.”

Breastfeeding helps you to lose weight

Contrary to popular belief, breastfeeding doesn’t necessarily help new mothers to shed weight any faster. Producing milk uses 200 to 500 calories a day, on average. That’s about the number burnt off in a gym workout and equal to those in a cheese and pickle sandwich.

However, breastfeeding mothers also produce the hormone prolactin that not only prompts milk production but stimulates appetite. The upshot? In many cases, women who breastfeed offset the calorie debt by consuming more food overall.

In a 2004 study, published in the American Journal of Clinical Nutrition, researchers from the Cincinnati Children's Hospital Medical Centre studied new mothers. In the first six months, the 81 non-breastfeeding mothers lost fat from their whole body, arms and legs faster than the 87 breastfeeding mums, who were shown to snack on more calories throughout the day.

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Credits to Yee Wai Loong

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