Placebo crackers are manufactured according to SOPs which have been developed taking into account the HACCP to maintain quality and safety and ensure the "Ready-to-eat placebo products" are safe. Data on the micronutrient concentrations and any potential bacteriological (Salmonella sp is negative, Bacillus cereus, Enterobacteriaceae, and Coagulase positive streptococci level are considered safe) and chemical contaminants (Pb, Hg, Cd, As, and Sn are not detected) in the placebo have been obtained based on the analysis in the laboratory of Saraswanti Indo Genetech, which has been accredited by KAN LP-184-IDN with SNI ISO/IEC 17025: 2008. Laboratory analysis of placebo samples will be repeated at the middle and the end of the RCT to check on the quality and safety of the placebo product.

Blood will be taken by a trained personnel and hemoglobin concentration (g/dL) in the mother will be analysed by complete blood count in a certified laboratory (Prodia Laboratory; Sysmex XN-1000).

Weighed records will be collected by the mothers on 3 non-consecutive days: 2 weekdays and 1 weekend day using a digital scale with precision of 4 grams (Kitchen Scale EK3131). On the next day after each weighed food record has been completed by the mother, an experienced research assistant will conduct a 24-hour recall on the mother using telephone/online communication. Results from the weighed record and recall will be combined to determine maternal food intake, which will be converted into nutrient intakes based on the weight and nutritional value of each food using the Indonesian Food Composition Table. The Multiple Source Method (MSM) program will be applied to estimate individual usual intakes of energy and nutrients as well as the usual intake distributions for the study population.

The deuterium dose-to-the mother technique will be performed to measure the volume of breast milk consumed by the infants and the status of breastfed infants. As much as 30 grams of Deuterium Oxide (D2O) are taken by the mother orally, which is then excreted into the breast milk consumed by the infant. Saliva sampling will be carried out according to protocol guidelines established by the International Atomic Energy Agency (IAEA; Human Health Series No. 7) with some adjustments to the number of days of sampling. Maternal and infant saliva samples will be taken on the 0th day before the mother is given D2O dose, and subsequently post-dose on day 2 or 3, day 8 or 9, and on day 13 or 14. A total of 2 mL of maternal and 1 mL of infant saliva will be collected on each sampling day. Saliva will be analyzed using Fourier Transform Infrared Spectrometry (FTIR), from which exclusive breastfeeding categorization and breast milk volume will be calculated using the Microsoft Excel Spreadsheet.

Full breast milk samples will be collected by mothers from one breast (washed with distilled, deionised water) using acid washed breast milk pumps (Medela Harmony Manual Breast Pump) into acid washed glass bottles. Mothers will be requested to refrain from breastfeeding on one breast at least 2 hours before the scheduled breast milk collection to allow for the collection of fore- and hindmilk.

Breast milk micronutrient concentrations, including Na, Mg, P, K, Ca, Fe, Cu, Zn, Se will be analysed using ICP- MS Agilent 7900; Free Thiamine, TMP, and TPP using HPLC-FLD Agilent 1200; Cobalamin using Competitive Chemiluminescent Enzyme Immunase IMMULITE 1000; Riboflavin, FAD, FMN, NAD, panthothenic acid, pyridoxal, pyridoxine, biotin using UPLC-MS with a Waters ACQUITY UPLC I-Class system coupled to a Sciex 4500 triple quadrupole mass spectrometer; Performed retinol, Alpha-carotene, Beta-carotene, Beta-cryptoxanthin, Alpha- tocopherol, and Gamma-tocopherol using HPLC Agilent 1260.

Data generated from the volume of infant's breast milk intake using Deuterium Oxide Dose-to- Mother Technique and analyzed breast milk micronutrient concentrations will be used to calculate breast milk micronutrient intakes of the infants at 5 months post-partum.

Data generated from maternal micronutrient concentrations in serum (Ferritin, Soluble Transferrin Receptor (sTfR), Retinol-Binding Protein (RBP), Zn, and Se) and adjusted for inflammation status, where appropriate, using C-reactive protein and Alpha-1-acid glycoprotein will be used to assess maternal micronutrient status.

The cutoffs used to define deficiency for each maternal biomarker will be as follows: adjusted serum ferritin, < 15 μg/L; adjusted sTfR, > 8.3 mg/L; adjusted zinc < 10.7 μmol/L; adjusted RBP < 1.20 μmol/L; and adjusted selenium < 0.82 μmol/L.

Data generated from infant's serum micronutrient concentrations (Ferritin, sTfR, RBP, Zn, and Se) at 5 months post- partum, adjusted for inflammation status, where appropriate using C-reactive protein and Alpha-1-acid glycoprotein will be used to assess infant micronutrient status at 5 months post-partum.

The cutoffs used to define deficiency for each biomarker among the infants will be as follows: adjusted ferritin, < 12 μg/ L, adjusted sTfR, > 8.3 mg/L; adjusted zinc < 9.9 μmol/L; adjusted RBP < 0.83 μmol/L (27); adjusted selenium < 0.82 μmol/L; vitamin B12 < 148 pmol/L.

The morbidity calendar for both mother and infant will be recorded by respondents independently and checked by research cadres once a week. The maternal morbidity calendar will be recorded over one month (for seizure, fever, headache, diarrhea, vaginal bleeding, cough, sore throat) at 14 weeks and 31-32 weeks of gestation, and 1 month and 4 months post-partum (for diarrhea, fever, cold, cough, vomit, ear infection, sore throat). The infant morbidity calendar will also be recorded over one month when the infant is 1 month and 4 months post-partum (for diarrhoea, fever, cold, cough, vomit, ear infection, sore throat). Digital thermometers will be provided to the respondents for self assessment of maternal and infant fever.