The association between sleep and fecundability: a Danish preconception cohort study

Area of Science:

• Reproductive Health
• Sleep Medicine
• Occupational Health

Background:

• Fecundability, the per-cycle probability of conception, is crucial for reproductive success.
• Factors influencing fecundability are extensively studied, with emerging interest in lifestyle and occupational influences.
• Previous research has not fully elucidated the impact of sleep patterns and work schedules on conception rates.

Purpose of the Study:

• To investigate the association between sleep duration, sleep disturbances, and occupational work times (day, evening, shift, night) with fecundability.
• To quantify the effects of these factors on the likelihood of conception in women attempting pregnancy.

Main Methods:

• Analysis of data from a preconception cohort study involving 10,475 Danish females aged 18-45 years.
• Baseline questionnaires collected information on sleep duration (hours/day), trouble sleeping frequency, and job time.
• Pregnancy status was tracked via follow-up questionnaires every 8 weeks for up to 12 months; proportional probabilities regression models were used.

Main Results:

• No significant associations were found between self-reported sleep duration (≤6, 7, or ≥9 hours/day) or trouble sleeping frequency and fecundability.
• Compared to day work, shift work was associated with a slightly higher fecundability (FR=1.12, 95% CI: 1.04-1.20).
• Night work showed a trend towards lower fecundability (FR=0.77, 95% CI: 0.49-1.22), though this finding was imprecise.

Conclusions:

• Sleep duration and subjective sleep disturbances do not appear to significantly affect a woman's probability of conception.
• Shift work may be associated with a modest increase in fecundability, whereas night work might be linked to a decrease, requiring further investigation.
• Limitations include potential misclassification of sleep and unmeasured confounding factors.