Does extremely early expression of colostrum after very preterm birth improve mother's own milk quantity? A cohort study.

Objective: Assess the relationship of time to first expression after very preterm birth and mothers' own milk quantity.
Design: A cohort study (nested within a randomised trial).
Setting: Four neonatal units in the UK.
Patients: 132 mothers of single or twin infants born at 23+0 to 31+6 weeks postmenstrual age.
Exposures: Time to the first attempt to express after birth.
Primary Outcomes: 24-hour mother's own milk yield on days 4, 14 and 21 after birth.
Results: Median time to first expression attempt was 6 hours. 51.7% expressed within 6 hours of birth (62/120) and 48.3% expressed more than 6 hours after birth (58/120). Expressing within 6 hours of birth was associated with higher milk yield on day 4 (88.3 g, 95% CI 7.1 to 169.4) and day 14 (155.7 g, 95% CI 12.2 to 299.3) but not on day 21 (73.6 g, 95% CI -91.4 to 238.7). There was an interaction between expressing frequency and time to first expression (p<0.005), with increased expressing frequency being associated with higher yield only in those who expressed within 6 hours. Expressing within 2 hours of birth was not associated with further milk yield increase.
Conclusions: Mothers who expressed within 6 hours of birth had higher milk yield, and a greater yield per expressing session, in the first 3 weeks after birth. This information will be highly motivating for families and the clinicians supporting them. There was no evidence of further benefit of extremely early expression (first 2 hours after birth).
Trial Registration Number: ISRCTN 16356650.
Competing Interests: Competing interests: MF receives an unrestricted research donation from Philips for research in infant nutrition, unrelated to this work. IL was previously on the working group for the British Association of Perinatal Medicine Quality Improvement Toolkit on perinatal optimisation of breast milk. The study funder (NIHR) had no role in the design, conduct or analysis of the study, or of the decision to submit for publication.
(© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY. Published by BMJ.)