Table 2. Quality of evidence profile for the assessed outcomes, adapted from GRADE [25].

Outcome (population)	Quality assessment					Quality	Importance
	N. studies	Limitation	Inconsistency	Indirectness	Imprecision
death (pregnant women)	five [91], [93], [96]–[98]	serious *	−	−		very low	Critical
death (general population)	eight [87]–[90], [92], [94], [95], [99]	serious†	no important inconsistency	very serious§	no important imprecision	very low	Critical
anaphylaxis (pregnant women)	five [91], [93], [96]–[98]	serious*	−	−		very low	Critical
anaphylaxis(general population)	eight [87]–[90], [92], [94], [95], [99]	serious†	no important inconsistency	very serious§	no important imprecision	very low	Critical
incidence of adverse reactions(pregnant women)	five [91], [93], [96]–[98]	serious*	−	−		very low	Important
incidence of adverse reactions(general population)	eight [87]–[90], [92], [94], [95], [99]	serious†	very serious‡	very serious§	no important imprecision	very low	Important

Notes:

All studies had observational design.

Publication bias could not be objectively assessed due to the small numbers of studies.

Imprecision could not be assessed since adequate meta-analysis calculation could not be performed.

RR: relative risk.

NE: Non-estimable.

−We could not access the item for this outcome.

^*Flawed measurement of outcome, as the study did not aimed to report the incidence of adverse reaction in pregnant women.

^†Some studies did not report the incidence of adverse reaction; the data was obtained with the authors.

^‡Heterogeneous results across studies were observed.

^§Different population (patients were not pregnant women and did not have syphilis) and intervention. In one study [95] other types of penicillin, besides benzathine, may have been used.