Thyrotrophin-releasing hormone--a lactation-promoting agent?

OBJECTIVE: To study the lactational and hormonal responses to nasal administration of thyrotrophin-releasing hormone (TRH) in puerperal women with inadequate lactation.

DESIGN: Prospective randomized double-blind placebo-controlled study.

SUBJECTS: 19 puerperal women with inadequate lactation (less than 50% of normal milk yield) on the 5th day postpartum.

INTERVENTIONS: 10 women were allocated to receive TRH administered by a nasal spray of 1 mg, four times daily, between suckling episodes, for 10 consecutive days starting on day 6 postpartum. Nine women were allocated to receive placebo sprays.

MAIN OUTCOME MEASURES: Daily milk yield, serum levels of prolactin and thyroid hormones.

RESULTS: Before treatment all the women had significant prolactin responses to TRH and suckling stimuli. At the end of 10 days of treatment, milk yield increased significantly in the TRH group from a mean of 142.0 (SD 33.9) to 253.0 (SD 105.3) g/day (P = 0.014). There was no significant change in the placebo group. Basal prolactin levels increased from a mean of 117.4 micrograms/l (SD 45.2) to 173.3 micrograms/l (SD 55.5) (P less than 0.001) in the TRH group whereas in the placebo group prolactin levels decreased from 137.2 (SD 69.5) to 82.0 (SD 37.7) micrograms/l. A further rise in prolactin levels and milk yield was seen in seven women in the TRH group who received a second 10-day course of TRH treatment at their own request. There was no significant change in levels of thyroid stimulating hormone, thyroxine and triiodothyronine during treatment in either of the two treatment groups and no signs of hyperthyroidism.

CONCLUSION: Repeated nasal TRH administration between suckling episodes may improve defective lactation.