title: Maternal neuroendocrine serum levels in exclusively breastfeeding mothers.
abstract: BACKGROUND
  Low milk supply is a common cause of early weaning, and supply issues are associated with dysregulation of thyroid function and prolactin. However, hormone levels compatible with successful breastfeeding are not well defined, limiting interpretation of clinical lab results. In this study we sought to quantify ranges for thyroid-stimulating hormone (TSH), free thyroxine (T4), total T4, and prolactin in a cohort of exclusively breastfeeding women.
  
  
  METHODS
  Women planning to breastfeed were recruited in the third trimester of pregnancy. Maternal endocrine function was assessed before and after a breastfeeding session at 2 and 8 weeks postpartum. We used paired t tests to determine whether values changed from the 2- to 8-week visit.
  
  
  RESULTS
  Of 52 study participants, 28 were exclusively breastfeeding, defined as only breastmilk feeds in the prior 7 days, at both the 2- and 8-week study visits. Endocrine function changed with time since delivery: the TSH level was higher, whereas total T4, free T4, and prolactin levels were lower, at the 8-week visit than at the 2-week visit (by paired t test, p≤0.01). We found a wide range of prolactin values at the 8-week visit, with a 5th percentile value of 9 ng/dL before feeding and 74 ng/dL at 10 minutes after feeding.
  
  
  CONCLUSIONS
  Neuroendocrine function changes during the first 8 weeks after birth, and a wide range of values is compatible with successful breastfeeding. Further studies are needed to define reference values in breastfeeding women.
authors.affiliation: 1 Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of North Carolina School of Medicine , Chapel Hill, North Carolina.
authors.forename: Alison M
authors.initials: AM
authors.lastname: Stuebe
authors.forename: Samantha
authors.initials: S
authors.lastname: Meltzer-Brody
authors.forename: Brenda
authors.initials: B
authors.lastname: Pearson
authors.forename: Cort
authors.initials: C
authors.lastname: Pedersen
authors.forename: Karen
authors.initials: K
authors.lastname: Grewen
mesh_terms: D000328:Adult; D001942:Breast Feeding; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008895:Milk, Human / Q000378:metabolism*; D009035:Mothers; D049590:Postpartum Period / Q000097:blood*; D011247:Pregnancy; D011263:Pregnancy Trimester, Third / Q000097:blood; D011388:Prolactin / Q000097:blood*; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood*
chemical_list: D011388:Prolactin; D013972:Thyrotropin; D013974:Thyroxine
references.citation: Exp Physiol. 2002 Mar;87(2):207-14
references.pmid: 11856965
references.citation: Ann Clin Biochem. 2013 Nov;50(Pt 6):595-602
references.pmid: 23873872
references.citation: J Clin Endocrinol Metab. 1974 Mar;38(3):413-23
references.pmid: 4815172
references.citation: J Clin Endocrinol Metab. 1977 Jun;44(6):1101-6
references.pmid: 874046
references.citation: Obstet Gynecol. 1985 Jun;65(6):785-8
references.pmid: 3923412
references.citation: Clin Chem. 1987 Jul;33(7):1217-9
references.pmid: 3109780
references.citation: Br J Psychiatry. 1987 Jun;150:782-6
references.pmid: 3651732
references.citation: J Clin Endocrinol Metab. 1989 May;68(5):946-55
references.pmid: 2715293
references.citation: Br J Psychiatry. 1990 Aug;157:288-90
references.pmid: 2224383
references.citation: J Postgrad Med. 1993 Jul-Sep;39(3):137-41
references.pmid: 8051643
references.citation: J Nutr. 1994 Aug;124(8):1248-57
references.pmid: 8064373
references.citation: Exp Physiol. 1996 Nov;81(6):1007-20
references.pmid: 8960706
references.citation: J Lipid Res. 2005 Jun;46(6):1320-30
references.pmid: 15741655
references.citation: Endocr J. 2005 Oct;52(5):587-91
references.pmid: 16284437
references.citation: Thyroid. 2007 Jan;17(1):11-8
references.pmid: 17274742
references.citation: Evid Rep Technol Assess (Full Rep). 2007 Apr;(153):1-186
references.pmid: 17764214
references.citation: J Clin Endocrinol Metab. 2008 Jun;93(6):2300-6
references.pmid: 18364382
references.citation: Pediatrics. 2008 Oct;122 Suppl 2:S69-76
references.pmid: 18829834
references.citation: Pediatrics. 2008 Oct;122 Suppl 2:S77-84
references.pmid: 18829835
references.citation: Biol Res Nurs. 2009 Apr;10(4):340-9
references.pmid: 19224938
references.citation: J Perinatol. 2010 Mar;30(3):155-62
references.pmid: 19609306
references.citation: Breastfeed Med. 2011 Feb;6(1):41-9
references.pmid: 21332371
references.citation: Pediatrics. 2012 Mar;129(3):e827-41
references.pmid: 22371471
references.citation: J Womens Health (Larchmt). 2013 Apr;22(4):352-61
references.pmid: 23586800
references.citation: Reproduction. 2003 Sep;126(3):371-82
references.pmid: 12968945