Table 3.

Risk of bias of included trials

Study	Randomisation appropriate	Allocation concealment appropriate	Blinding patient / investigator / outcome assessor	Selective reporting improbable	Absence of other factors potentially causing bias	ITT analysis appropriate	Risk of bias (study level)
Elder [19]	unclear	unclear	yes / unclear / unclear	uncleara, b	noc	nod	high
Mulla [20]	unclear	unclear	no / no / unclear	noa, e	noc, f	unclear	high
Williams [22]	unclear	unclear	no / no / unclear	noa, g	noc	noh	high
Kazemier [21]	yes	yes	yes / yes / yes	yes	yes	yes	low

^aSample size planning, predefinition of study outcomes and their analysis not reported

^bThe outcome “kernicterus” was reported together with other adverse outcomes, some of which were reported for only one study group

^cPatient flow unclear; unclear whether information on inclusion and exclusion criteria was complete

^dSome participants were excluded from the analysis; information on study discontinuations was insufficient

^eThe outcome “preterm labour” was reported only for the control group; one outcome usually reported in association with preterm labour, preterm birth, was not reported here

^fThe outcome “cystopyelitis” was not defined and it was therefore unclear whether upper and / or lower UTI were included

^gResults of one outcome not relevant to this assessment were reported incompletely

^hSome participants were excluded from the analysis; the reasons were not stated