Background The identification of specific age windows and targeted population subgroups is essential for directing future preventive interventions aimed at addressing infantile weight faltering during the initial critical 1,000 days of life. These efforts are crucial as they have the potential to significantly impact both short-term and long-term health outcomes and overall survival. Subject and methods This study constituted a secondary cross-sectional analysis of data derived from a prospective cohort study. The data encompassed 529 mother-newborn pairs, who were enrolled at birth and subsequently monitored for a period of 9 months at the well-child clinic. The study evaluated infant attendances, feeding patterns and weight growth. Results At birth, there were 113 (21.4%) small-for-gestational-age, 379 (71.6%) appropriate-for-gestational-age and 37(7.0%) large-for-gestational-age newborns. Female were 246 (46.5%) and male 283 (53.5%). The clinic attendance at the facility-based well-child clinic showed a decline from 98.1% at 6 weeks to 79.6% at 9 months of age. In parallel, pre-visit illness increased from 9.2% to 38.1%, infrequent feeding increased from 11.7% to 41.1%, and exclusive breastfeeding rate declined from 96.4% to 88.5%. Although 17% of the mothers in the cohort delayed initiating breastfeeding at birth, 96% of all these 529 mothers continued to breastfeed as at 9 months after birth. Cow milk supplementation was observed in 6.6% of cases, and complementary feeding with cow milk was noted in 38% of cases. Other milk feeds offered included soya and goat milk. The consumption of maize/millet/cassava porridge remained stable. Complementary family foods consisted mainly of carbohydrates (98.7%) and legumes (95.7%), as many families could not afford eggs or flesh foods. The weight z-score increments-over-time (velocity) significantly demonstrated earlier (4 weeks earlier) and higher weight faltering rates (22.6%) than the static (8.4-9.2%) or serial weight z-score methods of growth assessments. Infant weight deceleration was steepest during the age intervals between 6weeks and 14weeks. Weight z-score velocity plateaued between 6 and 9months of age. The mean weight increment percentages over the period of 9months for the small-for-gestational-age-born infants was 253% (sd 79), the appropriate-for-gestational-age-born infants was 172% (sd 48) and that for the large-for-gestational-age-born infants was 140% (sd 71), ANOVA p<0.001. However, when static measures were used to assess weight growth amongst these 3 categories of infants at 9months of age, the small-for-gestational age-born infants appeared to have the highest rate of underweight at 27.3%, while 7.6% of the appropriate-for-gestational-age-born infants were underweight. None of the large-for-gestational-age born infants was malnourished. The infant characteristics that significantly predicted postnatal weight deceleration were being born large-for-gestational age (OR=4.61[2.01, 10.59]) or male (OR=2.79 [OR=1.68, 4.62]). The small-for-gestational-age-born infants were 9.09times (95% CI 2.86, 33.33) more likely to experience weight acceleration, postnatally, compared to the other categories of infants. Conclusion This study highlights the considerable benefits (avoidance of mislabeling or failing to detect weight faltering) of utilizing weight increments or weight z-score velocity charts instead of static/serial measures for monitoring infant growth. It is essential to focus on the age intervals between 6 and 14 weeks after birth, male infants, large-for-gestational-age-born infants, previously ill infants, infant growth trajectories, types of feeds, and frequency of feeding during well-child clinic visits. Discouraging infant cow milk feeding practices is of utmost importance. Strengthening primary healthcare systems to enhance service delivery and increase contacts through home visits is imperative. KEY WORDS: weight faltering, increment versus static/serial weight assessments, frequency of feeding, exclusive breastfeeding, clinic attendances, sex, cow milk, soya milk, full exclusive breastfeeding, supplementary and complementary feeds.

The authors have declared no competing interest.

This study did not receive any funding

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Health Sciences Research Ethics committee/IRB of the University of the Free State in South Africa gave the ethical approval for this work. Approval was given for the collection of the primary data for the original study- Growth and growth faltering in a birth cohort in rural Rwanda: a longitudinal study with Ethical Clearance Number: UFS-HSD2018/1493/2901.

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