Hirahara 1998.

Methods	Random allocation to 2 groups using a computer‐generated random number table.
Participants	Inclusion criteria: women diagnosed with idiopathic hyperprolactinemia; had a history of 2 or more consecutive miscarriages without other etiologic factors; of normal weight (body mass index, 19 kg to 24 kg/m2). Exclusion criteria: women with prolactin disorders, endocrinologic abnormalities (e.g. luteal phase dysfunction, polycystic ovaries, LH hypersecretion, and thyroid hormone disorders or any other etiologic factors for recurrent spontaneous abortion). Hyperprolactinemic women who were taking medications that would affect serum prolactin levels were also excluded. Enrollment: 48 women were allocated (24 intervention, 24 control) before conception. After enrollment, 2 women in control group dropped out of the study. The reason for dropout was not given.
Interventions	Intervention group (n = 24): before conception, bromocriptine (2.5 to 5.0 mg/day) was given to women in this group until the end of the 9th week of gestation in whom the serum prolactin levels and the responses to TRH were normalized. Control group (n = 22): no treatment was given. 46 women in total (42 pregnancies ‐ 4/46 women did not conceive during the study period ‐ 21/24 in the bromocriptine group and 21/22 in the no‐treatment control.
Outcomes	Rates of live birth. Rates of miscarriage. Rates of conception. Prolactin levels.
Notes	Setting: the study took place in Yokohama City University Hospital, Japan. Date of study: not stated. Follow‐up: women were followed during the treatment and observation for 1 year. Prolactin levels were collected weekly between 4th and 12th gestational weeks during early pregnancy. Source of funding: supported in part by the National Cooperative Prevention Program for Mental and Physical Disorders, Ministry of Health and Welfare of Japan.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random schedules generated by computer.
Allocation concealment (selection bias)	Unclear risk	Not stated.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Blinding not reported. There was no placebo control (control was no treatment).
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not stated.
Incomplete outcome data (attrition bias) All outcomes	Low risk	2 women in control group dropped out of the study after enrollment. The reasons for dropouts were not explained. The rate of missing data was 4.2%.
Selective reporting (reporting bias)	Unclear risk	The trial protocol was not available. Each outcome discussed in the methods sections was reported up except that serum prolactin levels were only reported in those pregnant women. The trial report does not mention specific adverse events as
Other bias	Low risk	None apparent.

LH: luteinizing hormone
 TRH: thyrotropin‐releasing hormone