Mothers with HIV that exclusively breastfeed their babies for the first six months of life have a dramatically reduced risk of passing the infection to their infant, according to a new study in Africa.  Currently, World Health Organization (WHO) guidance says HIV positive women in the developing world, who can afford to use baby formula and have the facilities to prepare it safely, should do so.

But researchers at the Africa Centre for Health and Population Studies at the University of KwaZulu-Natal in South Africa, say that babies that are exclusively breastfed have half the risk of contracting HIV from their infected mothers as those who were also given baby formula or animal milk.  Hoosen Coovadia and colleagues tracked 1372 HIV-infected women and found a 4% risk of postnatal mother-to-child HIV transmission in babies fed only breast milk for six months after birth.

Mucus membrane

The infants who were breastfed but also given baby formula or animal milk were almost twice as likely to get the virus from the mother as those consuming breast milk alone, the researchers found. Babies fed solid foods in addition to breast milk were nearly 11 times more likely to become infected, they found.  The team suggests that breast milk may reinforce and protect the mucous membrane that lines the intestines, which may serve as a barrier to HIV infection.

Exclusive breastfeeding also reduces the incidence of breast conditions, such as mastitis and breast abscesses, which can increase the amount of the HIV virus in the mother's breast milk.  Babies that were exclusively breastfed were also twice as likely to survive past three months of age (6% risk of death), compared to those who received infant formula alone (11% risk of death), the study showed.

Risks outweighed

The findings indicate that for women in impoverished areas where AIDS is most prevalent, the health benefits of breast milk appear to outweigh the risk of passing on HIV through breastfeeding, the researchers say.   An estimated 150,000 to 350,000 babies are infected with HIV via their mothers' breast milk annually. If infected women living in impoverished areas exclusively breastfed their babies, between 50,000 to 100,000 lives could be saved annually, says Nigel Rollins, one of the researchers involved in the study.

"For the health and wellbeing of her child, exclusive breastfeeding is more than likely going to protect the child both from transmission and the other risks to her child's survival," Rollins says.  The researchers were not sure why the addition of solid food particularly heightened the mother-to-child transmission risk, but noted the larger, more complex proteins in such foods may help enable the virus to slip through the gut wall or otherwise facilitate viral entry.

Babies can remember things from the womb

for much longer than we thought, according to researchers at the University of Leicester.

Psychologist Alexandra Lamont found that year-old babies still recognized and had a preference for musical pieces that were played to them before being born. Previous studies have only shown babies being familiar with pre-birth experiences when they were a few days old.

Lamont had thought the children might develop a taste for the style of music played by their mothers, but this was not true. Instead, she was surprised to find that the babies could discriminate and remember individual songs.

"That's really quite remarkable. I'm excited about that," says Carolyn Rovee-Collier, a developmental psychologist from Rutgers University, New Jersey. She says the babies are probably sensing a vague familiarity to the music rather than really remembering it, rather like a feeling of deja-vu.

Look and learn

The study was done with 11 infants from families participating in a larger 20 year project coordinated by the BBC. Mothers were asked to listen to a song of their choice for half an hour every day during the last three months of their pregnancy.

The songs ranged from classical to reggae and pop, from the mother's favorite to something she thought would do her child good. After birth, the mothers didn't listen to their song choice again. "I suspect they got fed up with it," says Lamont.

After one year, Lamont visited the families and played 30 second sections of the mother's song, along with bits of other music matched for style, key, pace and volume. If the children kept looking at the speakers the music stayed on and this was taken to signify preference and recognition.

Lamont found that all the babies showed an over-riding preference for fast paced, more exciting music. But they also showed a statistical preference for their mother's song, regardless of the style.

Other children who did not have music played to them in the womb showed no preference for either of the matched tunes.

Our tune

Mothers probably cannot change their children's musical tastes by playing them certain songs in the womb says Lamont, but it may help babies bond with their mothers. "A couple of the babies had a strong attachment between the mother and the music," she says. "I'm not going to know for a few years whether this has any long term implications."

Previous research has shown infants remembering things like music, stories or people they encounter after birth for only a few days to months. Lamont says most people assumed that pre-birth memories would last about the same amount of time, if not less.

Lamont thinks that the exposure over three months could explain the results. Most studies only give infants a few weeks to get used to something before being tested to see if they remember it.

Also, adds Lamont, the mothers were told to sit and relax during their musical exposure. That could affect the mother's hormonal or chemical balance, perhaps further enhancing the effect.