Description of intervention
Participants in the intervention group received Pimpinella Anisum herbal tea (2 g of dried Anise plant plus 1 g of black tea). Those in the placebo group received black tea containing 3 g of dried black tea only. In both groups, tea was ingested 3 times [Participants in the intervention and placebo groups had no information about the type of herbal tea they were ingesting. To increase accuracy in relation to the intervention and placebo groups, the participants, the researcher, and statistical analyst did not know anything about the type of herbal tea ingested by the either the intervention or placebo groups.Participants in all groups used the Medela electronic machine to pump their milk at least 6 times a day (3–4 hourly upon waking at approximately 8am) for a period of 7 days. Excess milk was stored in the milk bank of Akbarabadi Hospital.