Semen quality and time to pregnancy: the Longitudinal Investigation of Fertility and the Environment Study.
OBJECTIVE
To assess semen parameters and couple fecundity as measured by time to pregnancy (TTP).


METHODS
Observational prospective cohort with longitudinal measurement of TTP.


METHODS
Sixteen Michigan/Texas counties.


METHODS
A total of 501 couples discontinuing contraception were followed for 1 year while trying to conceive; 473 men (94%) provided one semen sample, and 80% provided two samples.


METHODS
None.


METHODS
Using prospectively measured TTP, fecundability odds ratios (FORs) and 95% confidence intervals (CIs) were estimated for 36 individual semen quality parameters accounting for repeated semen samples, time off contraception, abstinence, enrollment site, and couples' ages, body mass indices, and serum cotinine concentrations.


RESULTS
In adjusted models, semen quality parameters were associated with significantly shorter TTP as measured by FORs >1: percent motility, strict and traditional morphology, sperm head width, elongation factor, and acrosome area. Significantly longer TTPs or FORs <1 were observed for morphologic categories amorphous and round sperm heads and neck/midpiece abnormalities. No semen quality parameters achieved significance when simultaneously modeling all other significant semen parameters and covariates, except for percent coiled tail when adjusting for sperm concentration (FOR 0.99; 95% CI 0.99-1.00). Male age was consistently associated with reduced couple fecundity (FOR 0.96; 95% CI 0.93-0.99), reflecting a longer TTP across all combined models. Female but not male body mass index also conferred a longer TTP (FOR 0.98; 95% CI 0.96-0.99).


CONCLUSIONS
Several semen measures were significantly associated with TTP when modeled individually but not jointly and in the context of relevant couple-based covariates.
Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Rockville, Maryland. Electronic address: louisg@mail.nih.gov.
Germaine M
GM
Buck Louis
Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Rockville, Maryland.
Rajeshwari
R
Sundaram
Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Rockville, Maryland.
Enrique F
EF
Schisterman
School of Rural Public Health, Texas A&M Health Science Center, College Station, Texas.
Anne
A
Sweeney
Department of Obstetrics and Gynecology, College of Medicine, Ohio State University, Columbus, Ohio.
Courtney D
CD
Lynch
Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Rockville, Maryland.
Sungduk
S
Kim
Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Rockville, Maryland.
José M
JM
Maisog
The EMMES Corporation, Rockville, Maryland.
Robert
R
Gore-Langton
Department of Urology, Stanford University, Palo Alto, California.
Michael L
ML
Eisenberg
Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Rockville, Maryland.
Zhen
Z
Chen
D000328:Adult; D015331:Cohort Studies; D004777:Environment; D005260:Female; D005298:Fertility / Q000502:physiology*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D011247:Pregnancy; D011446:Prospective Studies; D055101:Semen Analysis / Q000379:methods*; D061685:Time-to-Pregnancy / Q000502:physiology*
Epidemiology; fecundity; semen; sperm; time to pregnancy