Background and objectives: Cessation of exclusive breastfeeding (EBF) with early introduction of complementary food provides additional calories for catch-up growth but may also increase the risk of adverse outcomes. The objective of this study was to assess effects of exclusive breastfeeding for less than 6 months compared with 6 months in preterm and low birth weight infants.
Methods: Data sources include Medline, Scopus, Web of Science, CINAHL, and Index Medicus through June 30, 2021. Study selection includes randomized trials and observational studies. Primary outcomes were mortality, morbidity, growth, and neurodevelopment. Data were extracted and pooled using random-effects models. The Cochrane Risk of Bias 2 tool was used to assess the risk of bias of included studies.
Results: A total of 2 studies of 307 preterm or low birth weight infants were included. None of the study results could be pooled. Both studies compared EBF for 4 months to 6 months. Growth was similar between the 4-month and 6-month EBF groups for the following outcomes: weight-for-age z-score at corrected age 12 months (mean [standard deviation], 4-month group: -1.7 [1.1], 6-month group: -1.8 [1.2], 1 study, 188 participants, low certainty evidence), absolute weight gain (gram) from 16 to 26 weeks of age (4-month group: 1004 [366], 6-month group: 1017 [350], 1 study, 119 participants, very low certainty evidence), and linear growth gain (cm) from 16 to 26 weeks of age (4-month group: 4.3 [0.9], 6-month group: 4.5 [1.2], 1 study, 119 participants, very low certainty evidence). There were no apparent differences in reported morbidity symptoms. No difference in the timing to achieve motor development milestones between the 2 groups was found (1 study; 119 participants, very low certainty evidence). A limited number of studies prevented data pooling.
Conclusions: The evidence is very uncertain about the effect of exclusive breastfeeding for less than 6 months for preterm and low birth weight infants. Further studies are warranted to better answer this question.