title: Soy isoflavone intake and the likelihood of ever becoming a mother: the Adventist Health Study-2.
abstract: OBJECTIVE
  As little is known about the possible relationship between the intake of phytoestrogens and female fertility, we investigated the relationship between soy isoflavone intake and the risk of nulliparity and nulligravidity.
  
  
  METHODS
  A cross-sectional study of 11,688 North American Adventist women aged 30-50 years old with data regarding childbearing. These women were, as a group, characterized by a high proportion (54%) of vegetarians and a healthy lifestyle with a very low prevalence of smoking and alcohol use.
  
  
  RESULTS
  The mean isoflavone intake (17.9 mg per day) was very high compared to other Western populations. Only 6% of the women indicated no intake of isoflavones. We found, after adjustment for age, marital status, and educational level, an inverse relationship (P=0.05) between isoflavone intake and the likelihood of ever having become a mother. In women with high (≥40 mg/day) isoflavone intake (12% of this group of women), the adjusted lifetime probability of giving birth to a live child was reduced by approximately 3% (95% CI: 0, 7) compared to women with low (<10 mg/day) intake. No relationships were found between the isoflavone intake and parity or age at first delivery in parous women. A similar inverse relationship (P=0.03) was found between the isoflavone intake and the risk of nulligravidity with a 13% (95% CI: 2, 26) higher risk of never have been pregnant in women with high (≥40 mg/day) isoflavone intake. These relationships were found mainly in women who reported problems becoming pregnant.
  
  
  CONCLUSIONS
  The findings suggest that a high dietary isoflavone intake may have significant impact on fertility.
authors.affiliation: Department of Community Medicine, University of Tromsø, Tromsø, Norway.
authors.forename: Bjarne K
authors.initials: BK
authors.lastname: Jacobsen
authors.affiliation: Department of Epidemiology, Biostatistics and Population Medicine, School of Public Health, Loma Linda University, Loma Linda, CA, USA.
authors.forename: Karen
authors.initials: K
authors.lastname: Jaceldo-Siegl
authors.affiliation: Department of Epidemiology, Biostatistics and Population Medicine, School of Public Health, Loma Linda University, Loma Linda, CA, USA.
authors.forename: Synnøve F
authors.initials: SF
authors.lastname: Knutsen
authors.affiliation: Department of Epidemiology, Biostatistics and Population Medicine, School of Public Health, Loma Linda University, Loma Linda, CA, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Fan
authors.affiliation: Department of Epidemiology, Biostatistics and Population Medicine, School of Public Health, Loma Linda University, Loma Linda, CA, USA.
authors.forename: Keiji
authors.initials: K
authors.lastname: Oda
authors.affiliation: Department of Epidemiology, Biostatistics and Population Medicine, School of Public Health, Loma Linda University, Loma Linda, CA, USA.
authors.forename: Gary E
authors.initials: GE
authors.lastname: Fraser
keywords: Seventh-Day Adventist; fertility; isoflavones; phytoestrogens; soybeans
references.citation: J Womens Health (Larchmt). 2013 May;22(5):460-6
references.pmid: 23611121
references.citation: Public Health Nutr. 2010 Jun;13(6):812-9
references.pmid: 19968897
references.citation: Fertil Steril. 2004 Dec;82(6):1509-13
references.pmid: 15589851
references.citation: Fertil Steril. 2004 Jul;82(1):145-8, quiz 265
references.pmid: 15237003
references.citation: JAMA Intern Med. 2013 Jul 8;173(13):1230-8
references.pmid: 23836264
references.citation: J Natl Cancer Inst. 2012 Jan 4;104(1):67-76
references.pmid: 22158125
references.citation: Front Neuroendocrinol. 2010 Oct;31(4):400-19
references.pmid: 20347861
references.citation: Int J Epidemiol. 2008 Apr;37(2):260-5
references.pmid: 17726038
references.citation: Am J Med. 2009 Oct;122(10):939-46.e9
references.pmid: 19786161
references.citation: Complement Ther Clin Pract. 2008 May;14(2):132-5
references.pmid: 18396257
references.citation: Epidemiology. 2009 May;20(3):374-81
references.pmid: 19279491
references.citation: Maturitas. 2010 Aug;66(4):344-9
references.pmid: 20409653
references.citation: Public Health Nutr. 2011 Nov;14(11):1988-97
references.pmid: 21557864
references.citation: BJOG. 2010 Mar;117(4):500; author reply 500-1
references.pmid: 20374588
references.citation: J Nutr. 2010 Dec;140(12):2322S-2325S
references.pmid: 20980642
references.citation: Nutr J. 2011 Oct 06;10:105
references.pmid: 21978267
references.citation: J Nutr. 2010 Dec;140(12):2289S-2295S
references.pmid: 20980639
references.citation: Birth Defects Res C Embryo Today. 2008 Mar;84(1):1-15
references.pmid: 18383133
references.citation: Mol Cell Endocrinol. 2012 May 22;355(2):192-200
references.pmid: 22210487
references.citation: BJOG. 2009 Dec;116(13):1697-705
references.pmid: 19775307
references.citation: Am J Epidemiol. 2003 May 15;157(10):940-3
references.pmid: 12746247
references.citation: Eur J Epidemiol. 2012 Dec;27(12):923-31
references.pmid: 23224589
references.citation: Am J Clin Nutr. 2008 May;87(5):1422-7
references.pmid: 18469267
references.citation: Hum Reprod Update. 2009 Jul-Aug;15(4):423-40
references.pmid: 19299447
references.citation: Mol Cell Endocrinol. 2009 May 25;304(1-2):30-42
references.pmid: 19433245
references.citation: Reproduction. 2012 Mar;143(3):247-60
references.pmid: 22223686
references.citation: J Nutr. 2001 Jun;131(6):1826-32
references.pmid: 11385074
references.citation: Food Chem Toxicol. 2010 Oct;48(10):2549-76
references.pmid: 20558227
references.citation: Reprod Toxicol. 2011 Apr;31(3):272-9
references.pmid: 20955782
references.citation: J Sex Med. 2005 May;2(3):338-40
references.pmid: 16422864
references.citation: J Nutr. 2010 Jul;140(7):1350S-4S
references.pmid: 20484551
references.citation: Birth Defects Res C Embryo Today. 2011 Mar;93(1):3-11
references.pmid: 21425437