Table 3. Characteristics of included RCT studies.

Study ID	Participants	Intervention vs. comparison	Outcomes
DCCT Research Group 1996 USA [66]	94 women with 135 pregnancies in the intensive treatment group and 86 women with 135 pregnancies in the conventional treatment group	Intensive glycemic control (IGC) (multiple daily insulin injections or continuous infusion pump and self-monitoring)	PCC: At conception HbA1c: 7.4± SD 1.3 (N = 132) Congenital malformations:(1/135) Spontaneous abortion:(18/135) Perinatal mortality (Intrauterine deaths) (5/135) NO-PCC: At conception HbA1c: 8.1 ±SD 1.7 (N = 135) Congenital malformations: (8/135) Spontaneous abortion: (14/135) Perinatal mortality (Intrauterine deaths) (9/135)

NO-PCC: No preconception care, PCC: pre-conception care, HbA1c: Glycated Haemoglobin.