This study was a longitudinal design. The questionnaire on exclusive breastfeeding was administered and was validated against the deuterium oxide dose-to-mother technique to assess human milk intake of babies aged 3 and 6 mo.

This study is a longitudinal design that aimed to assess exclusive breastfeeding (EBF) practices in Asian countries and to compare the agreement in EBF between maternal recall and the dose-to-mother technique (DTM) technique. The questionnaire on exclusive breastfeeding was administered and was validated against the deuterium oxide dose-to-mother technique to assess human milk intake of babies aged 3 and 6 mo. The study planned to recruit 30 mother-baby pairs from each participated country. The was carried out in 7 countries in Asia, namely, Indonesia, Malaysia, Mongolia, Pakistan, Sri Lanka, Thailand, and Vietnam.

Mothers were approached at child birth, to explain the project objective and obtain written informed consent. A screening questionnaire was administered to obtain the interest to participate in the study. Only mothers who intend to exclusive breastfeeding till 6 mo will be eligible for further information and sample collection. Isotope dosing of mothers and saliva sample collection were done when the baby is at 3 mo ± 1wk, when a questionnaire (validation questionnaire) was administered. A basal saliva sample was collected prior to dosing with deuterium oxide. The isotope dosing of the mother was given and saliva samples were collected (post-dose) on day 1,2,3,4 and days 13,14.

The mother-baby pairs were followed up for another sample collection at 6 mo ± 1 wk and all procedures were repeated, including a questionnaire administration, basal sample collection, deuterium oxide dose administration, and post-dose sample collection. Body weight and height/length of mothers and infants were measured. All saliva samples were analyzed by Isotope ratio mass spectrometer (IRMS) or Fourier Transform Infrared Spectroscopy (FTIR).

Quantity of breast milk intake, non milk oral intake (NMOI) and maternal body composition were determined using standard assumption and formulae developed by the International Atomic Energy Agency (IAEA). Children with NMOI ≥ 86.6 g/day were considered as non-EBF using stable isotopic DTM technique. The overall agreement of EBF classification between the recall and DTM techniques is presented using Kappa statistic with 95% confidence interval.

Inclusion Criteria:

• Mother who practice exclusive breastfeeding
• Age of mother 18 - 40 years
• Parity: no more than 3
• Baby 3 month ± 7 days
• Nutritional status Weight-for-height Z score (WHZ) > -2
• Full term baby (37 - 40 weeks)

Exclusion Criteria:

• Twin or more baby
• Low birth weight
• Baby with oedema
• Mother with fluid retention disease (kidney disease, heart disease, hypothyroidism)
• Smoking mother
• Drinking alcohol mother

The participants were mother-baby pairs who were eligible according to the inclusion and exclusion criteria. There were recruited from hospitals, health clinics, or communities.