Birth characteristics in men with infertility.

RESEARCH QUESTION: Are low birth weight, prematurity, being born small for gestational age, or both, associated with a higher risk of male factor infertility in adulthood?

DESIGN

Retrospective study of a clinical sample of 892 men, diagnosed with an infertility factor (male, female, combined or unexplained) together with their female partner at a University Hospital clinic in Sweden between 2005 and 2010. Data on birth weight and gestational age at birth were retrieved from the Swedish Medical Birth Register. The distribution of non-optimal birth characteristics in relation to infertility factor was described. A control group was created consisting of two men for each index man, born in Sweden in the same year as each index men, as well as a reference group consisting of all men born in Sweden the same years.

RESULTS

The likelihood of having been born small for gestational age was almost fivefold higher in men with male factor infertility than in men with unexplained infertility (OR 4.84, 95% CI 1.32 to 17.80). Men with male factor infertility were more often born with non-optimal birth characteristics than the control group (14.8% versus 8.5%; P = 0.010) and the reference group (14.8% versus 11.4%; P < 0.001). Men with azoospermia were more often born with non-optimal birth characteristics, compared with men without azoospermia (21.3% versus 12.1%; P = 0.038).

CONCLUSIONS

The results suggest an association between intrauterine growth restriction and male factor infertility in adulthood.