IAEA study: Maternal HIV status does not influence growth, breast milk intake of HIV-negative infants

There are no differences in growth, body composition or breast milk intake among HIV-negative infants, whether born to HIV-positive or HIV-negative mothers, an IAEA-supported research project in Kenya has found.

The study, carried out under an IAEA Doctoral Coordinated Research Project (CRP), used the isotopic deuterium dilution technique (see box) to assess breast milk intake and body composition of infants at six weeks and six months of age. These indicators were compared between infants of HIV-positive mothers and those of HIV-negative mothers.

“We found that maternal HIV status does not influence growth, body composition or breast milk intake of HIV-uninfected children,” said Shadrack Oiye, the doctoral researcher who worked on this project, now a faculty member at Masinde Muliro University of Science and Technology in Kenya.

Exclusive breastfeeding

The study also showed that infants born to HIV-positive mothers were more likely to receive exclusive breastfeeding than those born to HIV-negative mothers.

“This was likely due to heightened counselling efforts to support HIV-infected mothers,” said Victor Owino, an IAEA nutrition scientist, who had served as the chief scientific investigator of the project and primary supervisor of the doctoral research before joining the IAEA. “This implies that counselling and breastfeeding support should be expanded to include all women regardless of HIV status.”

Because they are objective, nuclear techniques are more likely to deliver reliable results than other techniques, such us reliance on human recall.

“We were able to demonstrate that exclusive breastfeeding rates were likely to be overestimated if assessment was based on maternal recall,” Owino said. “Nuclear techniques could, therefore, be used to confirm breastfeeding practices as reported by mothers, especially if accurate tracking of global targets on breastfeeding is to be achieved.”

The project was a collaboration between the IAEA and the University of Nairobi, the Technical University of Kenya, the Kenya Medical Research Institute, the National Council for Science, Technology and Innovation as well as the Nutricia Foundation. It took place at the Maternal and Child Health Clinic of Siaya County Referral Hospital in Western Kenya, where 75 HIV-positive and 68 HIV-negative mothers with HIV-uninfected infants were recruited with their infants.

The study is a contribution to the IAEA’s efforts to help Member States address the HIV/AIDS pandemic. Similar earlier studies include a 1997-2000 Zimbabwe study, which compared the growth of HIV-exposed and HIV-unexposed children. It found that HIV-exposed children, regardless of HIV status, were more prone to retarded growth than HIV-unexposed children. However, the study took place before the advent of modern HIV suppression medication given to both mothers and infants. Also, both HIV-negative and HIV-positive mothers in the Kenya study received recommendations on breastfeeding.

Modern HIV-suppression drugs have greatly reduced the chances of HIV-infected mothers transmitting the virus to their infants through breastfeeding.

According to the World Health Organization (WHO), there were approximately 36.7 million people living with HIV at the end of 2015. Sub-Saharan Africa remains the region that is mostly affected, where the people living with HIV account for nearly 70% of HIV-infected people worldwide.

THE SCIENCE:

Measuring body composition with isotope techniques

Deuterium is a non-radioactive isotope of hydrogen that is given orally as deuterium oxide. After mixing with body water, it is eliminated from the body in urine, saliva, sweat and human milk.

Looked at simply, a person’s body weight comprises: fat mass (FM) and fat free mass (FFM). FFM is composed of mainly water with some proteins and minerals. It is assumed that FM has no water. Total body water can be measured by isotope dilution so the FM can be calculated. FM is used as a proxy indicator for the risk of obesity. Here is how:

A person drinks an accurately weighed amount of water labelled with deuterium (²H₂O) or oxygen-18 (H₂¹⁸O), stable isotopes of hydrogen and oxygen.

The labelled water mixes with the water in their body. After a few hours the isotope is evenly spread throughout the body water, which can be sampled in the form of saliva or urine.

The enrichment of deuterium or oxygen-18 in saliva or urine is measured.

Total body water is calculated from the measured isotope enrichment and the weight and enrichment of the labelled water consumed. From this we can estimate the FFM.

The hydration of the FFM changes with age. In new-born babies the FFM is 80 per cent water, but by the time they are adults it has reduced to 73 per cent. FFM is calculated using an appropriate hydration factor.

The fat mass is the difference between body weight and fat-free mass. The results can be expressed as a percentage of body weight.