title: Dairy intake and fecundability in 2 preconception cohort studies.
abstract: Animal studies have shown that a high intake of galactose, a breakdown product of lactose, increases ovarian toxicity. Few epidemiologic studies, to our knowledge, have examined the association between dairy intake and fertility, and they have had conflicting findings.
  
  
  
  We prospectively evaluated dairy intake in relation to fecundability among women who were planning for pregnancy.
  
  
  
  Data were derived from preconception cohort studies in Denmark (Snart Foraeldre) and North America [PRESTO (Pregnancy Study Online)] in which women completed a validated food-frequency questionnaire 10 d after enrollment. The dietary intake of dairy foods and their constituents was calculated based on reported frequencies, mean serving sizes, and standard recipes for mixed foods. Outcome data were updated every 8 wk for 12 mo or until reported conception. Analyses were restricted to 2426 women attempting pregnancy for ≤6 cycles at study entry. Fecundability ratios (FRs) and 95% CIs were estimated with the use of proportional probabilities regression models adjusted for potential confounders.
  
  
  
  FRs for total dairy intake (≥18 compared with <7 servings/wk) were 1.37 (95% CI: 1.05, 1.78) among 1126 Snart Foraeldre participants and 1.04 (95% CI: 0.78, 1.38) among 1300 PRESTO participants (pooled FR: 1.11; 95% CI: 0.94, 1.31). The elevated FR for total dairy intake among Snart Foraeldre participants was limited to milk consumption and found only among women aged <30 y. There was no clear association between low- or high-fat dairy intake and fecundability in either cohort. Although there was little evidence of an association between dietary intake of calcium, potassium, magnesium, or vitamin D and fecundability, a greater consumption of phosphorus and lactose was associated with slightly higher fecundability in both cohorts.
  
  
  
  Associations between dairy intake and fecundability were generally small and inconsistent across cohorts. Our findings do not support the hypotheses that a greater consumption of high-fat dairy improves fertility or that a greater consumption of lactose or low-fat dairy harms fertility.
authors.affiliation: Department of Epidemiology, Boston University School of Public Health, Boston, MA; lwise@bu.edu.
authors.forename: Lauren A
authors.identifier: 0000-0003-2138-3752
authors.initials: LA
authors.lastname: Wise
authors.affiliation: Department of Epidemiology, Boston University School of Public Health, Boston, MA.
authors.forename: Amelia K
authors.initials: AK
authors.lastname: Wesselink
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Ellen M
authors.initials: EM
authors.lastname: Mikkelsen
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Heidi
authors.initials: H
authors.lastname: Cueto
authors.affiliation: Department of Epidemiology, Boston University School of Public Health, Boston, MA.
authors.forename: Kristen A
authors.initials: KA
authors.lastname: Hahn
authors.affiliation: Department of Epidemiology, Boston University School of Public Health, Boston, MA.|RTI Health Solutions, Research Triangle Park, Durham, NC; and.
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Rothman
authors.affiliation: Department of Clinical Laboratory and Nutritional Sciences, University of Massachusetts Lowell, Lowell, MA.
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Tucker
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Henrik Toft
authors.initials: HT
authors.lastname: Sørensen
authors.affiliation: Department of Epidemiology, Boston University School of Public Health, Boston, MA.
authors.forename: Elizabeth E
authors.initials: EE
authors.lastname: Hatch
mesh_terms: D000328:Adult; D000367:Age Factors; D000818:Animals; D003611:Dairy Products; D003718:Denmark; D004032:Diet; D004034:Diet Surveys; D004041:Dietary Fats / Q000008:administration & dosage / Q000494:pharmacology; D005247:Feeding Behavior; D005260:Female; D005298:Fertility; D006801:Humans; D007785:Lactose / Q000494:pharmacology; D008892:Milk; D009656:North America; D010758:Phosphorus / Q000494:pharmacology; D011247:Pregnancy; D011446:Prospective Studies; D055815:Young Adult
chemical_list: D004041:Dietary Fats; D010758:Phosphorus; D007785:Lactose
keywords: Internet; calcium; dairy; fertility; lactose; prospective studies