Lipid concentrations and couple fecundity: the LIFE study.
BACKGROUND
A role of lipids in human fecundity is hypothesized as cholesterol is the main substrate for steroid synthesis and has also been shown to affect the hormonal milieu and steroidogenesis in both men and women.


OBJECTIVE
The objective of the study was to evaluate the association between male and female serum lipid concentrations and time to pregnancy (TTP).


METHODS
A population-based prospective cohort study recruiting couples from 16 counties in Michigan and Texas (2005-2009) using sampling frameworks allowing for identification of couples planning pregnancy in the near future.


METHODS
Five hundred one couples desiring pregnancy and discontinuing contraception were followed up for 12 months or until a human chorionic gonadotropin pregnancy was detected.


METHODS
Fecundability odds ratios (FORs) and 95% confidence intervals (CIs) were estimated after adjusting for age, body mass index, race, and education in relationship to female, male, and joint couple lipid concentrations.


RESULTS
Serum free cholesterol levels were higher on average among male and female partners of couples who did not became pregnant during the study follow-up (female, P = .04; male, P = .009), and levels in female partners were associated with significantly longer TTP in models based on both individual and couples concentrations (individual models: FOR 0.98, 95% CI 0.97, 0.99; couple models: FOR 0.98, 95% CI 0.97, 0.99). Male free cholesterol concentrations were associated with TTP only in the couple-based models (FOR 0.98, 95% CI 0.97, 0.99). Sensitivity analyses suggested that the observed associations are unlikely to be explained by potential unmeasured confounding such as diet.


CONCLUSIONS
Our results suggest that serum free cholesterol concentrations in both men and women have an effect on TTP, highlighting the importance of cholesterol and lipid homeostasis for male and female fecundity.
Division of Intramural Population Health Research (E.F.S., S.L.M., Z.C., G.M.B.L.), Eunice Kennedy Shriver National Institute of Child Health and Human Development, Rockville, Maryland 20852; Department of Biotechnical and Clinical Laboratory Sciences (R.W.B.), University at Buffalo, State University of New York at Buffalo, Buffalo, New York 14214; and Rollins School of Public Health (D.B.B.), Emory University, Atlanta, Georgia 30322.
Enrique F
EF
Schisterman
Sunni L
SL
Mumford
Richard W
RW
Browne
Dana Boyd
DB
Barr
Zhen
Z
Chen
Germaine M Buck
GM
Louis
D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D005191:Family Characteristics; D005260:Female; D005298:Fertility; D006801:Humans; D007246:Infertility / Q000097:blood / Q000453:epidemiology / Q000209:etiology; D008019:Life Style; D008055:Lipids / Q000097:blood*; D008297:Male; D008824:Michigan / Q000453:epidemiology; D009765:Obesity / Q000097:blood / Q000150:complications / Q000453:epidemiology; D050177:Overweight / Q000097:blood / Q000150:complications / Q000453:epidemiology; D011247:Pregnancy; D013781:Texas / Q000453:epidemiology; D055815:Young Adult
D008055:Lipids