Table 4. Summary of studies of the association between early breastfeeding initiation and morbidity outcomes (*Reference group).

Diarrhea
Study	Sample Size	Study Design	Exposure Definition	Outcome Definition	Effect Estimate	Quality
Clemmens	198	Prospective	Early (<3 days) vs. Late (≥3 days)*	Diarrhea	aRR: 0.74 (95% CI: 0.56–0.98)	Low
1999		Cohort	breastfeeding initiation	at <6 months
Clemmens	198	Prospective	Early (<3 days) vs. Late (≥3 days)*	Diarrhea	aRR: 0.95 (95% CI: 0.70–1.31)	Low
1999		Cohort	breastfeeding initiation	at 6–12 months
Hajeebhoy	6068	Cross-Sectional	Early (<1 hr) vs. Late (>1 hr)*	Diarrhea	aOR: 0.74 (95% CI:0.58–0.93)	Very low
2014			breastfeeding initiation	at <6 months
ARI
Hajeebhoy	6068	Cross-Sectional	Early (<1 hr) vs. Late (>1 hr)*	ARI	aRR: 0.91 (95% CI: 0.80–1.03)	Very low
2014			breastfeeding initiation	at <6 months
Hypothermia
Mullany	19180	Prospective	Early (<24 hrs)* vs. Late (>24 hrs)	Prevalence of axillary measures <35.0°C at <28 days	aRR: 1.19 (95% CI: 1.08–1.30)	Moderate
2010		Cohort	breastfeeding initiation
Van den Bosch	160	Randomized Trial	Immediate* vs. Mother's choice of breastfeeding initiation time	Rectal temperatue <36.5°C at 2, 4, and ~24 hrs after birth	RR: 2.45 (95% CI: 1.36–4.41)	High
1990
Umbilical Cord Infection
Mullany	1653	Prospective Cohort	Early (<1 hr) vs. Late (≥1 hr)*	1. Pus with any redness (Broad)	1. aRR: 0.74 (95% CI: 0.38–1.47)	Moderate

aRR