Table 8.

Grading of the confidence in the evidence for infections and timing of introduction of CFs

	Certainty assessment									Characteristics				Effect in the LoE
Line of evidence and initial rating	No studies	Design	RoB	Inconsistency	Generalisability	Imprecision	Magnitude	Dose response	Other	Comparator, population	Early CF	Late CF	Age	Relative	Certainty in the LoE	Certainty across LoE
Gastrointestinal infections
1 (main‐A) ++++	3	RCT	↔	↓	↓d	o	↔	o	↔	EBF	3‐4 m	6 m	4–6 m	No evidence for increased risk	++	++ (derived from RCTs)
2 (main‐B) +++	1	PC	↔	o	↔	↔	↔	o	↔	Mixed	< 3 m	> 3 m	4–6 m	No evidence for effect	+++
3 (S‐A) +++	4	PC, CSa	↓	↓	↔	↔	↔	o	↔	Mixed	n/a	n/a	infancy	No evidence for effect	+
Upper respiratory tract infections
1 (main‐A) ++++	3	RCT	n/a	n/a	n/a	n/a	n/a	n/a	n/a	EBF	3–4 m	6 m	4–6 m	Inconsistent	n/a
2 (main‐B) +++	1	PC	n/a	n/a	n/a	n/a	n/a	n/a	n/a	Mixed	< 3 m	> 3 m	4–6 m	Inconsistentb	n/a
Lower respiratory tract infections
1 (main‐A) ++++	1	RCT	↔	o	↓d	o	↔	o	↓c	EBF	3–4 m	6 m	4–6 m	No evidence for effect	++	++
2 (S‐A) +++	2	PC	↓	↔	↔	↔	↔	o	↔	Mixed	< 3 m	> 3 m	infancy	No evidence for effect	++
Undefined infections
1 (main‐A) ++++	1	RCT	↔	o	↓d	o	↔	o	↔	EBF	3–4 m	6 m	4–6 m	No evidence for effect	+++	+++
2 (main‐B) +++	1	PC	↔	o	↔	↔	↔	o	↔	PBF	< 6 m	> 6 m	0–18 m	No evidence for effect	+++
3 (S‐A) +++	1	PC	↓	o	↓d	↔	↔	o	↔	EBF	< 6 m	> 6 m	4–6 m	No evidence for effect	+

CS: cross‐sectional; CF: complementary food; EBF: exclusively breastfed; LoE: line of evidence; m: months; n/a: not applicable; PBF: partially breastfed; PC: prospective cohort; RCT: randomised controlled trial; RoB: risk of bias; ↓: downgrade; ↑: upgrade; ↔: no concern/impact; o: not evaluable.

(a) Baseline data of the Millennium Cohort Study. (b): Only one time period out of many. (c): Limited evidence in the main line of evidence. (d): Studied on exclusively breastfed infants only.